Abstract
Natural fibers and their products were prevalent since the early civilization of our society. Since then, the utilization and economic impact of natural fiber cultivation and down stream processing and products have been well established all over the world. This is attributed to the fact that every part of the fiber crop provides opportunities both in up and down streams processing for developing conventional as well as new products for wide ranging applications in textiles, packages, buildings, automotive, marine, electronic, leisure and household uses. This paper is a review on the tensile properties of natural fiber reinforced polymer composites. We choose coir fiber for our project. The mould die made up of stainless steel. We selected resin polyester in our project. Fiber will be treated by saline and NaOH to measure the mechanical properties such as tensile, flexural strength. Again fiber will be non-treated by saline and NaOH the same mechanical properties are measured.
LIST OF TABLES
TABLE NO. TABLE NAME PAGE NO.
4.1 Tensile S1 32
4.2 Tensile S2 33
4.3 Tensile S1 34
4.4 Impact test 35
4.5 Flexural S1 36
4.6 Flexural S2 37
4.7 Flexural S1 38
LIST OF FIGURES
FIG. NO. FIG. NAME PAGE NO.
4.1 Tensile S1 32
4.2 Tensile S2 33
4.3 Tensile S1 34
4.+5 Flexural S1 36
4.6 Flexural S2 37
4.7 Flexural S1 38
CHAPTER 1
INTRODUCTION
1.1 OVERVIEW OF COMPOSITES:
Processing of plastic composites using natural fibres as reinforcement has increased dramatically in recent years. The advantage of composite materials over conventional materials stem largely from their higher specific strength, stiffness and fatigue characteristics ,which enables structural designs to be more versatile. By definition these composite materials are engineered or naturally occurring materials made from two or more constituents materials with significantly different physical or chemical properties which remain separate and distinct at macroscopic and microscopic scale within the finished structure. These are materials that comprise strong load carrying material known as reinforcement imbedded in weaker material known as matrix. Reinforcement provides strength and rigidity, helping to support structural load. Modern composite materials constitute a significant proportion of the engineered materials market ranging from everyday products to sophisticated niche applications. While composites have already proven their worth as weight-saving materials, the current challenge is to make them cost effective. The efforts to produce economically attractive composite components have resulted in several innovative manufacturing techniques currently being used in the composites industry. It is obvious, especially for composites, that the improvement in manufacturing technology alone is not enough to overcome the cost hurdle. It is essential that there be an integrated effort in design, material, process, tooling, quality assurance, manufacturing, and even program management for composites to become competitive with metals. The composites industry has begun to recognize that the commercial applications of composites promise to offer much larger business opportunities than the aerospace sector due to the sheer size of transportation industry. Thus the shift of composite applications from aircraft to other commercial uses has become prominent in recent years. Increasingly enabled by the introduction of newer polymer resin matrix materials and high performance reinforcement fibres of glass, carbon and aramid, the penetration of these advanced materials has witnessed a steady expansion in uses and volume. The increased volume has resulted in an expected reduction in costs. High performance FRP can now be found in such diverse applications as composite armoring designed to resist explosive impacts, fuel cylinders for natural gas vehicles, windmill blades, industrial drive shafts, support beams of highway bridges and even paper making rollers. For certain applications, the use of composites rather than 3 metals has in fact resulted in savings of both cost and weight. Some examples are cascades for engines, curved fairing and fillets, replacements for welded metallic parts, cylinders, tubes, ducts, blade containment bands etc. Further, the need of composite for lighter construction materials and more seismic resistant structures has placed high emphasis on the use of new and advanced materials that not only decreases dead weight but also absorbs the shock & vibration through tailored microstructures. Composites are now extensively being used for rehabilitation/ strengthening of pre-existing structures that have to be retrofitted to make them seismic resistant, or to repair damage caused by seismic activity. Unlike conventional materials (e.g., steel), the properties of the composite material can be designed considering the structural aspects. The design of a structural component using composites involves both material and structural design.
Composite properties (e.g. stiffness, thermal expansion etc.) can be varied continuously over a broad range of values under the control of the designer. Careful selection of reinforcement type enables finished product characteristics to be tailored to almost any specific engineering requirement. Whilst the use of composites will be a clear choice in many instances, material selection in others will depend on factors such as working lifetime requirements, number of items to be produced (run length), complexity of product shape, possible savings in assembly costs and on the experience & skills the designer in tapping the optimum potential of composites. In some instances, best results may be achieved through the use of composites in conjunction with traditional materials. Reinforcement provides strength and rigidity, helping to support structural load. The matrix or binder (organic or inorganic) maintains the position and orientation of the reinforcement. The reinforcement may be particles, platelets or fibres and are usually added to improve mechanical property such as stiffness, strength and toughness of the matrix material. Long fibres that are oriented in the direction of loading offer the most efficient load transfer.
1.2 DEFINITION OF COMPOSITE
A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macroscale. The constituents retain their identities, that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another. Examples are cermets and metal-matrix composites
Kelly very clearly stresses that the composites should not be regarded simple as a combination of two materials. In the broader significance; the combination has its own distinctive properties. In terms of strength to resistance to heat or some other desirable quality, it is better than either of the components alone or radically different from either of them.
Beghezan defines as “The composites are compound materials which differ from alloys by the fact that the individual components retain their characteristics but are so incorporated into the composite as to take advantage only of their attributes and not of their short comings”, in order to obtain improved materials.
POLYMER COMPOSITE
The polymer composites are any of the combinations or compositions that comprise two or more materials as separate phases, at least one of which is a polymer. By combining a polymer with another material, such as glass, carbon, or another polymer, it is often possible to obtain unique combinations or levels of properties.
1.3 CLASSIFICATION OF COMPOSITES:
Composites are materials consist of two or more chemically distinct Constituents on a macro scale having a distinct interface separating them and having bulk properties significantly different from those of any of the constituents.
A Composite Material consists of two phases:-
1) Matrix phase
2) Reinforcement
Matrix phase
A material in which a continuous metallic phase (the matrix) is combined with another phase (the reinforcement) to strengthen the metal and increase high-temperature stability. The reinforcement is typically a ceramic in the form of particulates, platelets, whiskers, or fibers.
Reinforcement
Reinforcement in behavioral science, the presentation of a stimulus following a response that increases the frequency of subsequent responses. The part of the composite that provides strength, stiffness, and the ability to carry a load. The reinforcement material used in advanced composites is often a high-performance fiber.
1.3.1 Classification of Composites
Broadly, composite materials can be classified into three groups on the basis of matrix material. They are:
Metal Matrix Composites (MMC)
Ceramic Matrix Composites (CMC)
Polymer Matrix Composites (PMC)
1.3.1.1Metal Matrix Composites
A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal. The other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite. Metal Matrix Composites have many advantages over monolithic metals like higher specific modulus, higher specific strength, better properties at elevated temperatures, and lower coefficient of thermal expansion.
1.3.1.2 Ceramic matrix Composites
Ceramic Matrix Composite (CMC) is a material consisting of a ceramic matrix combined with a ceramic (oxides, carbides) dispersed phase. Ceramic Matrix Composites are designed to improve toughness of conventional ceramics, the main disadvantage of which is brittleness. Ceramic Matrix Composites are reinforced by either continuous (long) fibers or discontinuous (short) fibers.
A highly specialized advanced composite often used for aerospace applications. CMCs are stiff, lightweight, and can withstand extremely high temperatures.
1.3.1.3 Polymer Matrix Composites
A composite made from a polymer resin. Polymer matrix composites are not as strong or heat-resistant as metal matrix and ceramic matrix composites. Also equipments required for manufacturing polymer matrix composites are simpler. For this reason polymer matrix composites developed rapidly and soon became popular for structural applications. Composites are used because overall properties of the composites are superior to those of the individual components for example polymer/ceramic. Composites have a greater modulus than the polymer component but aren’t as brittle as ceramics.
Two types of polymer composites are:
• Fiber reinforced polymer (FRP)
• Particle reinforced polymer (PRP)
1.3.1.4 Fiber Reinforced Polymer:
Fiber Reinforced Polymers are by no means new to this world. It is only because of our fascination with petrochemical and non-petrochemical products that these wonderful materials exist. In fact, the polymers can be considered and used in the construction and construction repair. The petrochemical polymers are of low cost and are used more that natural materials. The Fiber Reinforced Polymers research is currently increasing and entails a quickly expanding field due to the vast range of both traditional and special applications in accordance to their characteristics and properties. Fiber Reinforced Polymers are related to the improvement of environmental parameters, consist of important areas of research demonstrating high potential and particularly great interest, as civil construction and concrete repair.
It is classified on two types
1. Short-fiber reinforced composites. Short-fiber reinforced composites consist of a matrix reinforced by a dispersed phase in form of discontinuous fibers (length < 100*diameter).
1. Composites with random orientation of fibers.
2. Composites with preferred orientation of fibers.
2. Long-fiber reinforced composites. Long-fiber reinforced composites consist of a matrix reinforced by a dispersed phase in form of continuous fibers.
1. Unidirectional orientation of fibers.
2. Bidirectional orientation of fibers (woven).
1.3.1.5 Particle Reinforced Polymer:
A particle has no long dimension. Particle composites consist of particles of one material dispersed in a matrix of a second material. Particles may have any shape or size, but are generally spherical, ellipsoidal, polyhedral, or irregular in shape. They may be added to a liquid matrix that later solidifies; grown in place by a reaction such as agehardening; or they may be pressed together and then inter-diffused via a powder process. The particles may be treated to be made compatible with the matrix, or they may be incorporated without such treatment. Particles are most often used to extend the strength or other properties of inexpensive materials by the addition of other materials.
Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as aluminium and amorphous materials, including polymers and carbon black. Particles are used to increase the modules of the matrix and to decrease the ductility of the matrix. Particles are also used to reduce the cost of the composites. Reinforcements and matrices can be common, inexpensive materials and are easily processed. Some of the useful properties of ceramics and glasses include high melting temp., low densities, high strength, stiffness, wear resistance, and corrosion resistance.
1.4 CHARACTERISTICS OF THE COMPOSITES
A composite material consists of two phases. It consists of one or more discontinuous phases embedded in a continuous phase. The discontinuous phase is usually harder and stronger than the continuous phase and is called the „reinforcement„ or „reinforcing material‟, whereas the continuous phase is termed as the „ matrix‟. The matrix is usually more ductile and less hard. It holds the dispersed phase and shares a load with it. Matrix is composed of any of the three basic material type i.e. polymers, metals or ceramics. The matrix forms the bulk form or the part or product. The secondary phase embedded in the matrix is a discontinuous phase. It is usually harder and stronger than the continuous phase. It servers to strengthen the composites and improves the overall mechanical properties of the matrix. Properties of composites are strongly dependent on the properties of their constituent materials, their distribution and the interaction among them. The composite properties may be the volume fraction sum of the properties of the constituents or the constituents may interact in a synergistic way resulting in
improved or better properties. Apart from the nature of the constituent materials, the geometry of the reinforcement (shape, size and size distribution) influences the properties of the composite to a great extent. The concentration distribution and orientation of the reinforcement also affect the properties. The shape of the discontinuous phase (which may by spherical, cylindrical, or rectangular cross-sanctioned prisms or platelets), the size and size distribution (which controls the texture of the material) and volume fraction determine the
interfacial area, which plays an important role in determining the extent of the interaction between the reinforcement and the matrix. Concentration, usually measured as volume or weight fraction, determines the contribution of a single constituent to the overall properties of the composites. It is not only the single most important parameter influencing the properties of the composites.
1.5 NATURAL FIBER REINFORCED COMPOSITES
The interest in natural fiber-reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. Plants, such as flax, cotton, hemp, jute, sisal, kenaf, pineapple, ramie, bamboo, banana, etc., as well as wood, used from time immemorial as a source of lignocellulosic fibers, are more and more often applied as the reinforcement of composites. Their availability, renewability, low density, and price as well as satisfactory mechanical properties make them an attractive ecological alternative to glass, carbon and man-made fibers used for the manufacturing of composites. The natural fiber-containing composites are more environmentally friendly, and are used in transportation (automobiles, railway coaches, aerospace), military applications, building and construction industries (ceiling paneling, partition boards), packaging, consumer products, etc.
1.5.1Classification of Natural Fibers:
Fibers are a class of hair-like material that are continuous filaments or are indiscrete elongated pieces, similar to pieces of thread. They can be spun into filaments, thread, or rope. They can be used as a component of composites materials. They can also be matted into sheets to make products such as paper or felt. Fibers are of two types: natural fiber and man made or synthetic fiber. Natural fibers include those made from plant, animal and mineral sources. Natural fibers can be classified according to their origin.
Animal fiber
Mineral fiber
Plant fiber
Animal Fiber
Animal fiber generally comprise proteins; examples mohair, wool, silk, alpaca,
angora.
Animal hair (wool or hair): Fiber taken from animals or hairy mammals. E.g. Sheep‟s wool, goat hair (cashmere, mohair), alpaca hair, horse hair, etc.
Silk fiber: Fiber collected from dried saliva of bugs or insects during the preparation of cocoons. Examples include silk from silk worms.
Avian fiber: Fibers from birds, e.g. feathers and feather fiber.
Mineral fiber:Mineral fibers are naturally occurring fiber or slightly modified fiber procured
from minerals. These can be categorized into the following categories:
Asbestos: The only naturally occurring mineral fiber. Varietions are serpentine and amphiboles, anthophyllite.
Ceramic fibers: Glass fibers (Glass wood and Quartz), aluminium oxide, silicon carbide, and boron carbide.
Metal fibers: Aluminum fibers
Plant fiber: Plant fibers are generally comprised mainly of cellulose: examples include
cotton, jute, flax, ramie, sisal and hemp. Cellulose fibers servers in the manufacture of paper and cloth. This fiber can be further categorizes into following.
Seed fiber: Fibers collected from the seed and seed case e.g. cotton and kapok.
Leaf fiber: Fibers collected from the leaves e.g. sisal and agave.
Skin fiber: Fibers are collected from the skin or bast surrounding the stem of their respective plant. These fibers have higher tensile strength than other fibers. Therefore, these fibers are used for durable yarn, fabric, packaging, and paper. Some examples are flax, jute, banana, hemp, and soybean.
Fruit fiber: Fibers are collected from the fruit of the plant, e.g. coconut (coir) fiber.
Stalk fiber: Fibers are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops including bamboo and grass. Tree wood is also such a fiber.
The natural fibers can be used to reinforce both thermosetting and thermoplastic matrices Thermosetting resins, such as epoxy, polyester, polyurethane, phenolic, etc. are commonly used today in natural fiber composites, in which composites requiring higher performance applications. They provide sufficient mechanical properties, in particular stiffness and strength, at acceptably low price levels. Considering the ecological aspects of material selection, replacing synthetic fibers by natural ones is only a first step. Restricting the emission of green house effect causing gases such as CO2 into the atmosphere and an increasing awareness of the finiteness of fossil energy resources are leading to developing new materials that are entirely based on renewable resources.
1.6 APPLICATIONS OF NATURAL FIBER COMPOSITES
The natural fiber composites can be very cost effective material for following
applications:
Building and construction industry: panels for partition and false ceiling,
partition boards, wall, floor, window and door frames, roof tiles, mobile
or pre-fabricated buildings which can be used in times of natural
calamities such as floods, cyclones, earthquakes, etc.
Storage devices: post-boxes, grain storage silos, bio-gas containers, etc.
Furniture: chair, table, shower, bath units, etc.
Electric devices: electrical appliances, pipes, etc.
Everyday applications: lampshades, suitcases, helmets, etc.
Transportation: automobile and railway coach interior, boat, etc.
The reasons for the application of natural fibers in the automotive industry
include:
Low density: which may lead to a weight reduction of 10 to 30%?
Acceptable mechanical properties, good acoustic properties.
Favorable processing properties, for instance low wear on tools, etc.
Options for new production technologies and materials.
Favorable accident performance, high stability, less splintering.
Favorable ecobalance for part production.
Favorable ecobalance during vehicle operation due to weight savings.
Occupational health benefits compared to glass fibers during production.
No off-gassing of toxic compounds (in contrast to phenol resin bonded
wood and recycled Cotton fiber parts).
Reduced fogging behavior.
Price advantages both for the fibers and the applied technologies.
1.7 ADVANTAGES OF NATURAL FIBER COMPOSITES:
The main advantages of natural fiber composite are:
Low specific weight, resulting in a higher specific strength and stiffness
than glass fiber.
It is a renewable source, the production requires little energy, and CO2
is used while oxygen is given back to the environment.
Producible with low investment at low cost, which makes the material
an interesting product for low wage countries.
Reduced wear of tooling, healthier working condition, and no skin
Irritation.
CHAPTER 2
LITERATURE REVIEW
This chapter outlines some of the recent reports published in literature on composites with special emphasis on erosion wear behavior of glass fiber reinforced polymer composites. The interest in natural fiber-reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. Plants, such as flax, cotton, hemp, jute, sisal, kenaf, pineapple, ramie, bamboo, banana, etc., are more often applied as the reinforcement of composites. These fibres are identified and various works are done by various researchers and scholars. The following are some of the works:
An attempt was made by K.G. Satyanarayana , K. Sukumaran, A.G. Kulkarni, S.G.K. Pillai, P.K. Rohatg [1] to find new uses for natural fibres — one renewable resource which is otherwise under-utilized. The structure and properties of the fibres, and the fabrication and physical and mechanical properties of their polyester-based composites are described. The performance of these composites is evaluated after exposure to indoor and outdoor weathering by both destructive and non-destructive testing methods. The preparation of various consumer articles such as a voltage stabilizer cover, mirror casing, a projector cover and roofing are also reported. This study demonstrates the potential of natural fibres for non-conventional applications and points out some of their limitations.
The mechanical behaviour high density polyethylene (HDPE) reinforced with continuous henequen fibres (Agave fourcroydes) was studied by P.J Herrera-Franco and A Valadez-González [2]. Fibre-matrix adhesion was promoted by fibre surface modifications using an alkaline treatment and a matrix preimpregnation together with a silane coupling agent. The use of the silane coupling agent to promote a chemical interaction, improved the degree of fibre-matrix adhesion. However, it was found that the resulting strength and stiffness of the composite depended on the amount of silane deposited on the fibre. A maximum value for the tensile strength was obtained for a certain silane concentration but when using higher concentrations, the tensile strength did not increase. Using the silane concentration that resulted in higher tensile strength values, the flexural and shear properties were also studied. The elastic modulus of the composite did not improve with the fibre surface modification. The elastic modulus, in the longitudinal fibre direction obtained from the tensile and flexural measurements was compared with values calculated using the rule of mixtures. It was observed that the increase in stiffness from the use of henequen fibres was approximately 80% of the calculated values. The increase in the mechanical properties ranged between 3 and 43%, for the longitudinal tensile and flexural properties, whereas in the transverse direction to the fibre, the increase was greater than 50% with respect to the properties of the composite made with untreated fibre composite. In the case of the shear strength, the increase was of the order of 50%. From the failure surfaces it was observed that with increasing fibre-matrix interaction the failure mode changed from interfacial failure to matrix failure.
Coconut fibre has been used as reinforcement in low-density polyethylene. The effect of natural waxy surface layer of the fibre on fibre/matrix interfacial bonding and composite properties has been studied by M.Brahmakumar, C. Pavithran and R.M. Pillai [3] by single fibre pullout test and evaluating the tensile properties of oriented discontinuous fibre composites. The waxy layer provided good fibre–matrix bond such that removal of the layer resulted in drastic decrease of the fibre pullout stress, increase of the critical fibre length and corresponding decrease in tensile strength and modulus of the composites. The waxy layer of polymeric nature also exhibited a stronger effect on interfacial bonding than by grafted layer of a C15 long-chain alkyl molecule onto the wax-free fibre. The morphological features of the fibre along with its surface compatibility with the matrix favours oriented flow of relatively long fibres along with the molten matrix during extrusion
Natural fibres (sisal, kenaf, hemp, jute and coir) reinforced polypropylene composites were processed by compression moulding using a film stacking method by Paul Wambua , Jan Ivens, Ignaas Verpoest [4]. The mechanical properties of the different natural fibre composites were tested and compared. A further comparison was made with the corresponding properties of glass mat reinforced polypropylene composites from the open literature. Kenaf, hemp and sisal composites showed comparable tensile strength and modulus results but in impact properties hemp appears to out-perform kenaf. The tensile modulus, impact strength and the ultimate tensile stress of kenaf reinforced polypropylene composites were found to increase with increasing fibre weight fraction. Coir fibre composites displayed the lowest mechanical properties, but their impact strength was higher than that of jute and kenaf composites. In most cases the specific properties of the natural fibre composites were found to compare favourably with those of glass.
Natural rubber is reinforced with untreated sisal and oil palm fibers chopped to different fiber lengths. The effects of concentration and modification of fiber surface in sisal/oil palm hybrid fiber reinforced rubber composites have been studied. Increasing the concentration of fibers resulted in reduction of tensile strength and tear strength, but increased modulus of the composites. Composites were prepared using fibers treated with varying concentrations of sodium hydroxide solution and for different time intervals. The vulcanisation parameters, processability characteristics, and stress–strain properties of these composites were analysed. The rubber/fiber interface was improved by the addition of a resorcinol-hexamethylene tetramine bonding system. The reinforcing property of the alkali treated fiber was compared with that of untreated fiber. The extent of fiber alignment and strength of fiber-rubber interface adhesion were analysed from the anisotropic swelling measurements by Maya Jacob , Sabu Thomas K.T. Varughese [5].
Moisture absorption of natural fiber plastic composites was tested by W. Wang, M. Sain and P.A. Coope [6] Moisture absorption of natural fiber plastic composites is one major concern in their outdoor applications. Traditionally diffusion theory is applied to understand the mechanism of moisture absorption; but it cannot address the relationship between the microscopic structure-infinite 3D-network and the moisture absorption. The purpose of this study is to introduce percolation theory into this field and conduct some preliminary work. First, two new concepts, accessible fiber ratio and diffusion-permeability coefficient, were defined; secondly, a percolation model was developed to estimate the critical accessible fiber ratio; finally, the moisture absorption and electrical conduction behavior of composites with different fiber loadings were investigated. At high fiber loading when accessible fiber ratio is high, the diffusion process is the dominant mechanism; while at low fiber loading close to and below percolation threshold, percolation is the dominant mechanism. The over-estimate of accessible fiber ratio led to discrepancies between the observed and model estimates.
Environmental awareness and an increasing concern with the greenhouse effect have stimulated the construction, automotive, and packing industries to look for sustainable materials that can replace conventional synthetic polymeric fibers. Flavio de Andrade Silva,Nikhilesh Chawla ,Romildo Dias de Toledo Filho [7] found that natural fibers seems to be a good alternative since they are readily available in fibrous form and can be extracted from plant leaves at very low costs. In this work we have studied the monotonic tensile behavior of a high performance natural fiber: sisal fiber. Tensile tests were performed on a microforce testing system using four different gage lengths. The cross-sectional area of the fiber was measured using scanning electron microscope (SEM) micrographs and image analysis. The measured Young’s modulus was also corrected for machine compliance. Weibull statistics were used to quantify the degree of variability in fiber strength, at the different gage lengths. The Weibull modulus decreased from 4.6 to 3.0 as the gage length increased from 10 mm to 40 mm, respectively. SEM was used to investigate the failure mode of the fibers. The failure mechanisms are described and discussed in terms of the fiber microstructure as well as defects in the fibers.
C. Alves, P.M.C. Ferrão,A.J. Silva,L.G. Reis [8] made the idea of introducing making use of natural jute fiber composites in automotive components. Nowadays, the world faces unprecedented challenges in social, environmental and economical dimensions, in which the industrial design has showed an important contribution with solutions that provide positive answers regarding these problems. In particular, due to its relevance, the automotive industry confronts a moment of crises, and based on the ecodesign of products it has been transforming the challenges in opportunities. In this context, the use of natural fiber composites, produced in developing countries, have presented several social, environmental and economical advantages to design “green” automotive components. Thus, this work through LCA method demonstrates the possibility to use natural fibers through a case study design which investigates the environmental improvements related to the replacement of glass fibers for natural jute fibers, to produce a structural frontal bonnet of an off-road vehicle (Buggy). Results pointed out the advantages of applying jute fiber composites in Buggy enclosure.
2.1 OBJECTIVES OF THE RESEARCH WORK
The objectives of the project are outlined below.
Fabrication of Pandanus Odoratissimus fibre polyester matrix composite
with/without alkali treatment.
Evaluation of mechanical properties (tensile strength, flexural,
impact strength etc.
Besides the above all the objective is to develop relatively low cost composites by incorporating cheaper reinforcing phases into a polymeric resin. Also this work is expected to introduce a new class of polymer composite that might find applications in erosive operational situations.
And also to find the properties of the fibre after it is been alkali treated( NaOH).
CHAPTER 3
3. MATERIALS AND METHODS
3.1. Introduction
This chapter describes the details of processing of the composites and the Experimental procedures followed for their characterization and tribological Evaluation. The raw materials used in this work are
1. Pandanus Odoratissimus fibre
2. Polyester resin
3.2.Processing of the Composites
Specimen preparation
Pandanus Odoratissimus fibers are reinforced in unsaturated isophthalic polyester Resin to prepare the composite. The composite slabs are made by conventional compression moulding Technique. Two percent cobalt nephthalate (as accelerator) is mixed thoroughly in isophthalic polyester resin and then 3% methyl-ethyl-ketone-peroxide (MEKP) as hardener is mixed in the resin prior to reinforcement. Composites are made on pure resin with Pandanus Odoratissimus fibre under random orientation(arrangement of fibre in the composites). The castings are put under load for about 3 to 4 hours for proper curing at room temperature. Similar procedure adapted for the preparation of the alkali treated Pandanus Odoratissimus fibre polymer composites.
3.3 characterization of the composites:
3.3.1 Tensile Strength:
The tensile test is generally performed in universal testing machine. The tensile test is performed in UTM. The tension test is generally performed on flat specimens. The test-piece used here was of rectangular type and having dimensions according to the standards.The dimension of the specimen is 165mm*10mm*3mm. A thickness of 3mm is maintained for the treated as well as non-treated composite specimen. A uni-axial load is applied through the ends. The tension test was performed on the samples as per ASTM D638 test standards.
3.3.2 Flexural Strength:
The determination of flexural strength is an important characterization of any Structural material. It is the ability of a material to withstand the bending before Reaching the breaking point. Conventionally a three point bend test is conducted for finding out this material property In the present investigation also the composites were subjected to this test in a testing machine . The photograph of the machine and the loading arrangement for the specimens are shown in Figure. A span of 50 mm was taken samples are taken from each test and the results are averaged. The flexural test is performed in UTM. Flexural test was performed on all the three samples as per ASTM D 790 test standards. Flexural strength can be calculated using this formula :
Flexural Strength = 3PL / 2bh2
Where P= applied central load (N)
L= test span of the sample (m)
b= width of the specimen (m)
h= thickness of specimen under test (m)
Flexural tests monitor behavior of materials in simple beam loading; or transverse beam tests. Specimens are supported as a simple beam, with the compressive load applied at midpoint, and maximum fiber stress and strain calculated. The three point bending flexural test measures bend or fracture strength, yield strength, modulus of elasticity in bending, flexural stress, flexural strain, and flexural stress strain materials response. Flexural strength represents the highest stress experienced within the material at its moment of rupture.
3.3.3 Impact test:
Impact tests are designed to measure the resistance to failure of a material to a suddenly applied force. The test measures the impact energy, or the energy absorbed prior to fracture.The tests are done as per ASTM D 256 using an impact tester .
The standard specimen for ASTM D 256 is 64 x 12 x 3 mm. The most common methods of measuring impact energy are the
Izod test
Charpy test
Charpy test:
While most commonly used on metals, it is also used on polymers, ceramics and composites. The Charpy test is most commonly used to evaluate the relative toughness or impact toughness of materials and as such is often used in quality control applications where it is a fast and economical test. It is used more as a comparative test rather than a definitive test.
The impact test is used to find out the energy required to break the specimen. The un-notched Charpy impact test is conducted to study the impact energy according to the ASTM D256. The un-notched specimens are kept in cantilever position and the pendulum swings around to break the specimen. The impact energy (J) is calculated from the dial gauge, which is fitted on the machine. Five samples are taken for each test and the results are averaged.
3.4 MATERIAL PREPARATION
Required material are Pandanus Odoratissimus fibre, polyester resin. Pandanus Odoratissimus fibre are prepared from Pandanus Odoratissimus plant, Polyester resins are produced by the poly condensation of saturated and unsaturated dicarboxylic acids with glycols.
3.4.1 PANDANUS ODORATISSIMUS PLANT:
Pandanus is a genus of monocots with about 600 known species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. They are classified in the order Pandanales, family Pandanaceae. Often called pandanus palms, these plants are not closely related to palm trees. The botanical family Pandanaceae consists of three genera, namely Sararanga (two species), Freycinetia (175 spp.), and Pandanus (about 600 spp.). The species vary in size from small shrubs less than 1 metre (3.3 ft) tall, to medium-sized trees 20 metres (66 ft) tall, typically with a broad canopy, heavy fruit, and moderate growth rate. The trunk is stout, wide-branching, and ringed with many leaf scars. They commonly have many thick prop roots near the base, which provide support as the tree grows top-heavy with leaves, fruit, and branches. The leaves are strap-shaped, varying between species from 30 centimetres (12 in) to 2 metres (6.6 ft) or more long, and from 1.5 centimetres (0.59 in) up to 10 centimetres (3.9 in) broad.
They are dioecious, with male and female flowers produced on different plants. The flowers of the male tree are 2–3 centimetres (0.79–1.2 in) long and fragrant, surrounded by narrow, white bracts. The female tree produces flowers with round fruits that are also bract-surrounded. The fruits are globose, 10–20 centimetres (3.9–7.9 in) in diameter, and have many prism-like sections, resembling the fruit of the pineapple. Typically, the fruit changes from green to bright orange or red as it matures. The fruit of some species are edible. Pandanus fruit are eaten by animals including bats, rats, crabs, elephants and monitor lizards, but the vast majority of species are dispersed primarily by water.
a) Pandanus plant b) Pandanus flower (fragrance flower)
3.4.1.1 EXTRACTING THE FIBRE:
Fibre is extracted by a process known as decortication, where roots are crushed and beaten by a rotating wheel set with blunt knives, so that only fibres remain. But we have extracted the fibre from the prop roots my hammering. Proper drying is important as fibre quality depends largely on moisture content. Artificial drying has been found to result in generally better grades of fibre than sun drying.
prop roots
3.4.1.2 PANDANUS ODORATISSIMUS FIBRE:
The fibre we have used is extracted from the prop roots after extraction , it is shown in the figures (a) and (b) respectively below..
(a) (b)
3.4.1.3 USES OF PANDANUS ODORATISSIMUS :
Pandan is used for handicrafts. Craftswomen collect the pandan leaves from plants in the wild. Only the young leaves are cut so the plant will naturally regenerate. The young leaves are sliced in fine strips and sorted for further processing. Weavers produce basic pandan mats of standard size or roll the leaves into pandan ropes for other designs. This is followed by a coloring process, in which pandan mats are placed in drums with water-based colors. After drying, the colored mats are shaped into final products, such as place mats or jewelry boxes. Final color touch-ups may be applied.
Pandan (P. amaryllifolius) leaves are used in Southeast Asian cooking to add a distinct aroma to rice and curry dishes such as nasi lemak, kaya ('jam')preserves, and desserts such as pandan cake. Pandan leaf can be used as a complement to chocolate in many dishes, such as ice cream. Fresh leaves are typically torn into strips, tied in a knot to facilitate removal, placed in the cooking liquid, then removed at the end of cooking. Dried leaves and bottled extract may be bought in some places.
Kewra is an extract distilled from the pandanus flower, used to flavor drinks and desserts in Indian cuisine. Also, kewra or kewadaa is used in religious worship, and the leaves are used to make hair ornaments worn for their fragrance as well as decorative purpose in western India.
Throughout Oceania, almost every part of the plant is used, with various species different from those used in Southeast Asian cooking. Pandanus trees provide materials for housing; clothing andtextiles including the manufacture of dilly bags (carrying bags), fine mats or ‘ie toga; food, medication, decorations, fishing, and religious uses.
3.4.2 POLYESTER RESIN
Polyester resins are unsaturated resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Polyester resins are used in sheet moulding compound, bulk moulding compound and the toner of laser printers. Wall panels fabricated from polyester resins reinforced with fiberglass — so-called fiberglass reinforced plastic (FRP) — are typically used in restaurants, kitchens, restrooms and other areas that require washable low-maintenance walls.
Unsaturated polyesters are condensation polymers formed by the reaction of polyols (also known as polyhydric alcohols), organic compounds with multiple alcohol or hydroxy functional groups, with saturated or unsaturated dibasic acids. Typical polyols used are glycols such as ethylene glycol; acids used are phthalic acid and maleic acid. Water, a by-product of esterification reactions, is continuously removed, driving the reaction to completion. The use of unsaturated polyesters and additives such as styrene lowers the viscosity of the resin. The initially liquid resin is converted to a solid by cross-linking chains. This is done by creating free radicals at unsaturated bonds, which propagate in a chain reaction to other unsaturated bonds in adjacent molecules, linking them in the process. The initial free radicals are induced by adding a compound that easily decomposes into free radicals. This compound is usually and incorrectly known as the catalyst. Substances used are generally organic peroxides such as benzoyl peroxide or methyl ethyl ketone peroxide.
Polyester resins are thermosetting and, as with other resins, cure exothermically. The use of excessive catalyst can, therefore, cause charring or even ignition during the curing process. Excessive catalyst may also cause the product to fracture or form a rubbery material.
3.4.3 ALKALI TREATMENT:
There are several different methods for modification of surface energy of the fibre and the polymer. Physical methods like stretching, calendaring and the production of hybrid yams, change the structural and surface properties of the fibre and thereby influence the mechanical bonding in the matrix. Another physicl method used is electric discharge, which will increase the roughness of the fibres and active its surface oxidation leading to the increase in aldehyde groups. It can also generate cross linkings and free radicals.
Oxidizing agents such as Na or Ca and hydrogen peroxides can be used to remove dust and oil from natural fibres. Alkaline treatment with NaOH , known as mercerization , extracts lignin and hemicelluloses, increasing the tensile strength and elongation at break of the composite. In this process the fibres are immersed in 4% solution of NaOH for 1 to 2 hours, followed by continous washing and drying in room temperature.
CHAPTER 4
RESULTS AND DISCUSSION
4.1 INTRODUCTION
This chapter presents the physical and mechanical characterization of the class of polymer matrix composites developed for the present investigation. They are Uni directional sisal fiber reinforced polyester resin composites. Details of processing of these composites and the tests conducted on them have been described in the previous chapter. The results of various characterization tests are reported here. They include evaluation of tensile strength, flexural strength, young’s modulus, impact strength has been studied and discussed.
4.2 COMPOSITE CHARACTERIZATION
4.2.1 Mechanical properties of composites
The characterization of the composites reveals that inclusion of alkali treatment has strong influence on the physical and mechanical properties of composites. The modified values of the properties of the composites under this investigation are presented and compared against the untreated pandanus polyester composite. A gradual increase in impact strength as well as flexural strength with the weight fraction of fiber is noticed. It can be clearly seen that treated fibre shows increase in performance comparing the untreated one. It may be mentioned here that both tensile and flexural strengths are important for recommending any composite as a candidate for structural applications.
4.2.2Tensile Strength:
For untreated pandanus fibre: s-1
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 29.91 Kg
3 Yield Elongation 1.73 mm
4 Break Force 29.9 Kg
5 Break Elongation 1.73 mm
6 Tensile Strength at Yield 49.85 Kg/cm²
7 Tensile Strength at Break 49.85 Kg/cm²
8 % Elongation 1.73 %
For untreated pandanus fibre:s-2
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 16.13 Kg
3 Yield Elongation 2.52 mm
4 Break Force 17.4 Kg
5 Break Elongation 2.73 mm
6 Tensile Strength at Yield 26.89 Kg/cm²
7 Tensile Strength at Break 28.96 Kg/cm²
8 % Elongation 2.73 %
For alkali treated pandannus fibre: s-1
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 18.03 Kg
3 Yield Elongation 1.31 mm
4 Break Force 18.0 Kg
5 Break Elongation 1.31 mm
6 Tensile Strength at Yield 30.05 Kg/cm²
7 Tensile Strength at Break 30.05 Kg/cm²
8 % Elongation 1.31 %
From the obtained results of the tensile testing of the pandannus fibre it can be noted that there is difference in their properties between the alkali treated and non-treated fibres.
4.2.3 Impact strength:
The impact test was the charpy and izod from the results below it can be noted that there is difference in strength between the alkali treated and non treated pandannus fibres.
4.2.4 Flexural test:
Through the three point bend test the following results were obtained for the pandannus fibre. The graph and result shows the variation in properties between the treated and non-treated fibre.
S.NO SPECIMEN NO JOULES
1 Pandnus Untreated 1 5.794
2 Pandnus Untreated 2.282
3 Pandnus NaohTreat 2 2.020
4 Pandnus NaohTreat 3 0.968
For alkali treated pandannus fibre:s-1
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 5.22 Kg
4 MOD2 DEFLECTION 2.41 mm
5 Stress 1 0.00
6 Stress 2 4.35
7 FLEXURAL MODULES -2175.63 N/mm2
For alkali treated pandannus fibre:s-2
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 6.49 Kg
4 MOD2 DEFLECTION 2.09 mm
5 Stress 1 0.00
6 Stress 2 5.41
7 FLEXURAL MODULES -2703.43 N/mm2
For nontreated pandannus fibre: s-1
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 18.18 Kg
4 MOD2 DEFLECTION 5.65 mm
5 Stress 1 0.00
6 Stress 2 15.15
7 FLEXURAL MODULES -7573.85 N/mm2
CHAPTER 5
CONCLUSION
This analytical and experimental investigation on the pandannus odourrattus polymer composites leads to the following conclusions:
This work shows that successful fabrication of a pandannus odourrattus polymer composites with and without alkali treatment by compression moulding technique.
The cheaper natural fibre like pandannus fibre can be used to make an effective fibre polymer composite.
The performance of the non treated pandannus fibre was found to be superior to the treated pandannus fibre.
In flexural test, the non treated pandannus fibre was found to have more strength than the treated pandannus fibre.
From both the impact and tensile test also the non treated pandannus fibre was found to be superior to the treated pandannus fibre..
CHAPTER 6
REFERENCES
[1] K.G. Satyanarayana , K. Sukumaran, A.G. Kulkarni, S.G.K. Pillai, P.K. Rohatg Regional Research Laboratory, Council of Scientific and Industrial Research (CSIR), India Fabrication and properties of natural fibre-reinforced polyester composites
[2] P.J Herrera-Franco and A Valadez-González Centro de Investigación Cientı́fica de Yucatán, A.C., Calle 43 #.130, Col. Chuburná de Hidalgo, C.P. 97200 Mérida, Yucatán, Mexico Mechanical properties of continuous natural fibre-reinforced polymer composites , Received 28 November 2002. Revised 15 June 2003. Accepted 11 September 2003.
[3] M. Brahmakumar, C. Pavithran and R.M. Pillai , Regional Research laboratory (CSIR), Council of Scientific and Ind. Res., Thiruvananthapuram 695 019, Kerala, India ,Received 13 October 2003. Revised 27 July 2004. Accepted 1 September 2004.
[4] Paul Wambua , Jan Ivens, Ignaas Verpoest, Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44 B-3001 Leuven, Belgium , Accepted 21 February 2003.
[5]Maya Jacob , Sabu Thomas K.T. Varughese , School of Chemical Sciences, Mahatma Gandhi University, Priyadarshini Hills P.O. Kottayam, Kerala, 686 560, India Thermal Research Center, KORADI, Nagpur, 441 111, India,Received 8 August 2002. Revised 19 June 2003. Accepted 25 June 2003.
[6] W. Wang, M. Sain and P.A. Coope , Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Canada ,Received 20 July 2005. Accepted 20 July 2005.
[7]Flavio de Andrade Silva,Nikhilesh Chawla ,Romildo Dias de Toledo Filho, Civil Engineering Department, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil ,School of Materials, Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-8706, USA ,Received 23 May 2008. Revised 12 September 2008. Accepted 1 October 2008.
[8] C. Alves, P.M.C. Ferrão,A.J. Silva,L.G. Reis Instituto Superior Tecnico, Rovisco Pais Av., 1049-001 Lisbon, Portugal Universidade Estadual do Sudoeste da Bahia, Praça da Primavera, 40, 45700-000 Itapetinga, Brazil ,Instituto de Artes Visuais, Design e Marketing, D. Carlos I Av., 4, 1200-649 Lisbon, PortugalReceived 12 August 2009. Revised 7 October 2009. Accepted 26 oct.
Natural fibers and their products were prevalent since the early civilization of our society. Since then, the utilization and economic impact of natural fiber cultivation and down stream processing and products have been well established all over the world. This is attributed to the fact that every part of the fiber crop provides opportunities both in up and down streams processing for developing conventional as well as new products for wide ranging applications in textiles, packages, buildings, automotive, marine, electronic, leisure and household uses. This paper is a review on the tensile properties of natural fiber reinforced polymer composites. We choose coir fiber for our project. The mould die made up of stainless steel. We selected resin polyester in our project. Fiber will be treated by saline and NaOH to measure the mechanical properties such as tensile, flexural strength. Again fiber will be non-treated by saline and NaOH the same mechanical properties are measured.
LIST OF TABLES
TABLE NO. TABLE NAME PAGE NO.
4.1 Tensile S1 32
4.2 Tensile S2 33
4.3 Tensile S1 34
4.4 Impact test 35
4.5 Flexural S1 36
4.6 Flexural S2 37
4.7 Flexural S1 38
LIST OF FIGURES
FIG. NO. FIG. NAME PAGE NO.
4.1 Tensile S1 32
4.2 Tensile S2 33
4.3 Tensile S1 34
4.+5 Flexural S1 36
4.6 Flexural S2 37
4.7 Flexural S1 38
CHAPTER 1
INTRODUCTION
1.1 OVERVIEW OF COMPOSITES:
Processing of plastic composites using natural fibres as reinforcement has increased dramatically in recent years. The advantage of composite materials over conventional materials stem largely from their higher specific strength, stiffness and fatigue characteristics ,which enables structural designs to be more versatile. By definition these composite materials are engineered or naturally occurring materials made from two or more constituents materials with significantly different physical or chemical properties which remain separate and distinct at macroscopic and microscopic scale within the finished structure. These are materials that comprise strong load carrying material known as reinforcement imbedded in weaker material known as matrix. Reinforcement provides strength and rigidity, helping to support structural load. Modern composite materials constitute a significant proportion of the engineered materials market ranging from everyday products to sophisticated niche applications. While composites have already proven their worth as weight-saving materials, the current challenge is to make them cost effective. The efforts to produce economically attractive composite components have resulted in several innovative manufacturing techniques currently being used in the composites industry. It is obvious, especially for composites, that the improvement in manufacturing technology alone is not enough to overcome the cost hurdle. It is essential that there be an integrated effort in design, material, process, tooling, quality assurance, manufacturing, and even program management for composites to become competitive with metals. The composites industry has begun to recognize that the commercial applications of composites promise to offer much larger business opportunities than the aerospace sector due to the sheer size of transportation industry. Thus the shift of composite applications from aircraft to other commercial uses has become prominent in recent years. Increasingly enabled by the introduction of newer polymer resin matrix materials and high performance reinforcement fibres of glass, carbon and aramid, the penetration of these advanced materials has witnessed a steady expansion in uses and volume. The increased volume has resulted in an expected reduction in costs. High performance FRP can now be found in such diverse applications as composite armoring designed to resist explosive impacts, fuel cylinders for natural gas vehicles, windmill blades, industrial drive shafts, support beams of highway bridges and even paper making rollers. For certain applications, the use of composites rather than 3 metals has in fact resulted in savings of both cost and weight. Some examples are cascades for engines, curved fairing and fillets, replacements for welded metallic parts, cylinders, tubes, ducts, blade containment bands etc. Further, the need of composite for lighter construction materials and more seismic resistant structures has placed high emphasis on the use of new and advanced materials that not only decreases dead weight but also absorbs the shock & vibration through tailored microstructures. Composites are now extensively being used for rehabilitation/ strengthening of pre-existing structures that have to be retrofitted to make them seismic resistant, or to repair damage caused by seismic activity. Unlike conventional materials (e.g., steel), the properties of the composite material can be designed considering the structural aspects. The design of a structural component using composites involves both material and structural design.
Composite properties (e.g. stiffness, thermal expansion etc.) can be varied continuously over a broad range of values under the control of the designer. Careful selection of reinforcement type enables finished product characteristics to be tailored to almost any specific engineering requirement. Whilst the use of composites will be a clear choice in many instances, material selection in others will depend on factors such as working lifetime requirements, number of items to be produced (run length), complexity of product shape, possible savings in assembly costs and on the experience & skills the designer in tapping the optimum potential of composites. In some instances, best results may be achieved through the use of composites in conjunction with traditional materials. Reinforcement provides strength and rigidity, helping to support structural load. The matrix or binder (organic or inorganic) maintains the position and orientation of the reinforcement. The reinforcement may be particles, platelets or fibres and are usually added to improve mechanical property such as stiffness, strength and toughness of the matrix material. Long fibres that are oriented in the direction of loading offer the most efficient load transfer.
1.2 DEFINITION OF COMPOSITE
A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macroscale. The constituents retain their identities, that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another. Examples are cermets and metal-matrix composites
Kelly very clearly stresses that the composites should not be regarded simple as a combination of two materials. In the broader significance; the combination has its own distinctive properties. In terms of strength to resistance to heat or some other desirable quality, it is better than either of the components alone or radically different from either of them.
Beghezan defines as “The composites are compound materials which differ from alloys by the fact that the individual components retain their characteristics but are so incorporated into the composite as to take advantage only of their attributes and not of their short comings”, in order to obtain improved materials.
POLYMER COMPOSITE
The polymer composites are any of the combinations or compositions that comprise two or more materials as separate phases, at least one of which is a polymer. By combining a polymer with another material, such as glass, carbon, or another polymer, it is often possible to obtain unique combinations or levels of properties.
1.3 CLASSIFICATION OF COMPOSITES:
Composites are materials consist of two or more chemically distinct Constituents on a macro scale having a distinct interface separating them and having bulk properties significantly different from those of any of the constituents.
A Composite Material consists of two phases:-
1) Matrix phase
2) Reinforcement
Matrix phase
A material in which a continuous metallic phase (the matrix) is combined with another phase (the reinforcement) to strengthen the metal and increase high-temperature stability. The reinforcement is typically a ceramic in the form of particulates, platelets, whiskers, or fibers.
Reinforcement
Reinforcement in behavioral science, the presentation of a stimulus following a response that increases the frequency of subsequent responses. The part of the composite that provides strength, stiffness, and the ability to carry a load. The reinforcement material used in advanced composites is often a high-performance fiber.
1.3.1 Classification of Composites
Broadly, composite materials can be classified into three groups on the basis of matrix material. They are:
Metal Matrix Composites (MMC)
Ceramic Matrix Composites (CMC)
Polymer Matrix Composites (PMC)
1.3.1.1Metal Matrix Composites
A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal. The other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite. Metal Matrix Composites have many advantages over monolithic metals like higher specific modulus, higher specific strength, better properties at elevated temperatures, and lower coefficient of thermal expansion.
1.3.1.2 Ceramic matrix Composites
Ceramic Matrix Composite (CMC) is a material consisting of a ceramic matrix combined with a ceramic (oxides, carbides) dispersed phase. Ceramic Matrix Composites are designed to improve toughness of conventional ceramics, the main disadvantage of which is brittleness. Ceramic Matrix Composites are reinforced by either continuous (long) fibers or discontinuous (short) fibers.
A highly specialized advanced composite often used for aerospace applications. CMCs are stiff, lightweight, and can withstand extremely high temperatures.
1.3.1.3 Polymer Matrix Composites
A composite made from a polymer resin. Polymer matrix composites are not as strong or heat-resistant as metal matrix and ceramic matrix composites. Also equipments required for manufacturing polymer matrix composites are simpler. For this reason polymer matrix composites developed rapidly and soon became popular for structural applications. Composites are used because overall properties of the composites are superior to those of the individual components for example polymer/ceramic. Composites have a greater modulus than the polymer component but aren’t as brittle as ceramics.
Two types of polymer composites are:
• Fiber reinforced polymer (FRP)
• Particle reinforced polymer (PRP)
1.3.1.4 Fiber Reinforced Polymer:
Fiber Reinforced Polymers are by no means new to this world. It is only because of our fascination with petrochemical and non-petrochemical products that these wonderful materials exist. In fact, the polymers can be considered and used in the construction and construction repair. The petrochemical polymers are of low cost and are used more that natural materials. The Fiber Reinforced Polymers research is currently increasing and entails a quickly expanding field due to the vast range of both traditional and special applications in accordance to their characteristics and properties. Fiber Reinforced Polymers are related to the improvement of environmental parameters, consist of important areas of research demonstrating high potential and particularly great interest, as civil construction and concrete repair.
It is classified on two types
1. Short-fiber reinforced composites. Short-fiber reinforced composites consist of a matrix reinforced by a dispersed phase in form of discontinuous fibers (length < 100*diameter).
1. Composites with random orientation of fibers.
2. Composites with preferred orientation of fibers.
2. Long-fiber reinforced composites. Long-fiber reinforced composites consist of a matrix reinforced by a dispersed phase in form of continuous fibers.
1. Unidirectional orientation of fibers.
2. Bidirectional orientation of fibers (woven).
1.3.1.5 Particle Reinforced Polymer:
A particle has no long dimension. Particle composites consist of particles of one material dispersed in a matrix of a second material. Particles may have any shape or size, but are generally spherical, ellipsoidal, polyhedral, or irregular in shape. They may be added to a liquid matrix that later solidifies; grown in place by a reaction such as agehardening; or they may be pressed together and then inter-diffused via a powder process. The particles may be treated to be made compatible with the matrix, or they may be incorporated without such treatment. Particles are most often used to extend the strength or other properties of inexpensive materials by the addition of other materials.
Particles used for reinforcing include ceramics and glasses such as small mineral particles, metal particles such as aluminium and amorphous materials, including polymers and carbon black. Particles are used to increase the modules of the matrix and to decrease the ductility of the matrix. Particles are also used to reduce the cost of the composites. Reinforcements and matrices can be common, inexpensive materials and are easily processed. Some of the useful properties of ceramics and glasses include high melting temp., low densities, high strength, stiffness, wear resistance, and corrosion resistance.
1.4 CHARACTERISTICS OF THE COMPOSITES
A composite material consists of two phases. It consists of one or more discontinuous phases embedded in a continuous phase. The discontinuous phase is usually harder and stronger than the continuous phase and is called the „reinforcement„ or „reinforcing material‟, whereas the continuous phase is termed as the „ matrix‟. The matrix is usually more ductile and less hard. It holds the dispersed phase and shares a load with it. Matrix is composed of any of the three basic material type i.e. polymers, metals or ceramics. The matrix forms the bulk form or the part or product. The secondary phase embedded in the matrix is a discontinuous phase. It is usually harder and stronger than the continuous phase. It servers to strengthen the composites and improves the overall mechanical properties of the matrix. Properties of composites are strongly dependent on the properties of their constituent materials, their distribution and the interaction among them. The composite properties may be the volume fraction sum of the properties of the constituents or the constituents may interact in a synergistic way resulting in
improved or better properties. Apart from the nature of the constituent materials, the geometry of the reinforcement (shape, size and size distribution) influences the properties of the composite to a great extent. The concentration distribution and orientation of the reinforcement also affect the properties. The shape of the discontinuous phase (which may by spherical, cylindrical, or rectangular cross-sanctioned prisms or platelets), the size and size distribution (which controls the texture of the material) and volume fraction determine the
interfacial area, which plays an important role in determining the extent of the interaction between the reinforcement and the matrix. Concentration, usually measured as volume or weight fraction, determines the contribution of a single constituent to the overall properties of the composites. It is not only the single most important parameter influencing the properties of the composites.
1.5 NATURAL FIBER REINFORCED COMPOSITES
The interest in natural fiber-reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. Plants, such as flax, cotton, hemp, jute, sisal, kenaf, pineapple, ramie, bamboo, banana, etc., as well as wood, used from time immemorial as a source of lignocellulosic fibers, are more and more often applied as the reinforcement of composites. Their availability, renewability, low density, and price as well as satisfactory mechanical properties make them an attractive ecological alternative to glass, carbon and man-made fibers used for the manufacturing of composites. The natural fiber-containing composites are more environmentally friendly, and are used in transportation (automobiles, railway coaches, aerospace), military applications, building and construction industries (ceiling paneling, partition boards), packaging, consumer products, etc.
1.5.1Classification of Natural Fibers:
Fibers are a class of hair-like material that are continuous filaments or are indiscrete elongated pieces, similar to pieces of thread. They can be spun into filaments, thread, or rope. They can be used as a component of composites materials. They can also be matted into sheets to make products such as paper or felt. Fibers are of two types: natural fiber and man made or synthetic fiber. Natural fibers include those made from plant, animal and mineral sources. Natural fibers can be classified according to their origin.
Animal fiber
Mineral fiber
Plant fiber
Animal Fiber
Animal fiber generally comprise proteins; examples mohair, wool, silk, alpaca,
angora.
Animal hair (wool or hair): Fiber taken from animals or hairy mammals. E.g. Sheep‟s wool, goat hair (cashmere, mohair), alpaca hair, horse hair, etc.
Silk fiber: Fiber collected from dried saliva of bugs or insects during the preparation of cocoons. Examples include silk from silk worms.
Avian fiber: Fibers from birds, e.g. feathers and feather fiber.
Mineral fiber:Mineral fibers are naturally occurring fiber or slightly modified fiber procured
from minerals. These can be categorized into the following categories:
Asbestos: The only naturally occurring mineral fiber. Varietions are serpentine and amphiboles, anthophyllite.
Ceramic fibers: Glass fibers (Glass wood and Quartz), aluminium oxide, silicon carbide, and boron carbide.
Metal fibers: Aluminum fibers
Plant fiber: Plant fibers are generally comprised mainly of cellulose: examples include
cotton, jute, flax, ramie, sisal and hemp. Cellulose fibers servers in the manufacture of paper and cloth. This fiber can be further categorizes into following.
Seed fiber: Fibers collected from the seed and seed case e.g. cotton and kapok.
Leaf fiber: Fibers collected from the leaves e.g. sisal and agave.
Skin fiber: Fibers are collected from the skin or bast surrounding the stem of their respective plant. These fibers have higher tensile strength than other fibers. Therefore, these fibers are used for durable yarn, fabric, packaging, and paper. Some examples are flax, jute, banana, hemp, and soybean.
Fruit fiber: Fibers are collected from the fruit of the plant, e.g. coconut (coir) fiber.
Stalk fiber: Fibers are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops including bamboo and grass. Tree wood is also such a fiber.
The natural fibers can be used to reinforce both thermosetting and thermoplastic matrices Thermosetting resins, such as epoxy, polyester, polyurethane, phenolic, etc. are commonly used today in natural fiber composites, in which composites requiring higher performance applications. They provide sufficient mechanical properties, in particular stiffness and strength, at acceptably low price levels. Considering the ecological aspects of material selection, replacing synthetic fibers by natural ones is only a first step. Restricting the emission of green house effect causing gases such as CO2 into the atmosphere and an increasing awareness of the finiteness of fossil energy resources are leading to developing new materials that are entirely based on renewable resources.
1.6 APPLICATIONS OF NATURAL FIBER COMPOSITES
The natural fiber composites can be very cost effective material for following
applications:
Building and construction industry: panels for partition and false ceiling,
partition boards, wall, floor, window and door frames, roof tiles, mobile
or pre-fabricated buildings which can be used in times of natural
calamities such as floods, cyclones, earthquakes, etc.
Storage devices: post-boxes, grain storage silos, bio-gas containers, etc.
Furniture: chair, table, shower, bath units, etc.
Electric devices: electrical appliances, pipes, etc.
Everyday applications: lampshades, suitcases, helmets, etc.
Transportation: automobile and railway coach interior, boat, etc.
The reasons for the application of natural fibers in the automotive industry
include:
Low density: which may lead to a weight reduction of 10 to 30%?
Acceptable mechanical properties, good acoustic properties.
Favorable processing properties, for instance low wear on tools, etc.
Options for new production technologies and materials.
Favorable accident performance, high stability, less splintering.
Favorable ecobalance for part production.
Favorable ecobalance during vehicle operation due to weight savings.
Occupational health benefits compared to glass fibers during production.
No off-gassing of toxic compounds (in contrast to phenol resin bonded
wood and recycled Cotton fiber parts).
Reduced fogging behavior.
Price advantages both for the fibers and the applied technologies.
1.7 ADVANTAGES OF NATURAL FIBER COMPOSITES:
The main advantages of natural fiber composite are:
Low specific weight, resulting in a higher specific strength and stiffness
than glass fiber.
It is a renewable source, the production requires little energy, and CO2
is used while oxygen is given back to the environment.
Producible with low investment at low cost, which makes the material
an interesting product for low wage countries.
Reduced wear of tooling, healthier working condition, and no skin
Irritation.
CHAPTER 2
LITERATURE REVIEW
This chapter outlines some of the recent reports published in literature on composites with special emphasis on erosion wear behavior of glass fiber reinforced polymer composites. The interest in natural fiber-reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. Plants, such as flax, cotton, hemp, jute, sisal, kenaf, pineapple, ramie, bamboo, banana, etc., are more often applied as the reinforcement of composites. These fibres are identified and various works are done by various researchers and scholars. The following are some of the works:
An attempt was made by K.G. Satyanarayana , K. Sukumaran, A.G. Kulkarni, S.G.K. Pillai, P.K. Rohatg [1] to find new uses for natural fibres — one renewable resource which is otherwise under-utilized. The structure and properties of the fibres, and the fabrication and physical and mechanical properties of their polyester-based composites are described. The performance of these composites is evaluated after exposure to indoor and outdoor weathering by both destructive and non-destructive testing methods. The preparation of various consumer articles such as a voltage stabilizer cover, mirror casing, a projector cover and roofing are also reported. This study demonstrates the potential of natural fibres for non-conventional applications and points out some of their limitations.
The mechanical behaviour high density polyethylene (HDPE) reinforced with continuous henequen fibres (Agave fourcroydes) was studied by P.J Herrera-Franco and A Valadez-González [2]. Fibre-matrix adhesion was promoted by fibre surface modifications using an alkaline treatment and a matrix preimpregnation together with a silane coupling agent. The use of the silane coupling agent to promote a chemical interaction, improved the degree of fibre-matrix adhesion. However, it was found that the resulting strength and stiffness of the composite depended on the amount of silane deposited on the fibre. A maximum value for the tensile strength was obtained for a certain silane concentration but when using higher concentrations, the tensile strength did not increase. Using the silane concentration that resulted in higher tensile strength values, the flexural and shear properties were also studied. The elastic modulus of the composite did not improve with the fibre surface modification. The elastic modulus, in the longitudinal fibre direction obtained from the tensile and flexural measurements was compared with values calculated using the rule of mixtures. It was observed that the increase in stiffness from the use of henequen fibres was approximately 80% of the calculated values. The increase in the mechanical properties ranged between 3 and 43%, for the longitudinal tensile and flexural properties, whereas in the transverse direction to the fibre, the increase was greater than 50% with respect to the properties of the composite made with untreated fibre composite. In the case of the shear strength, the increase was of the order of 50%. From the failure surfaces it was observed that with increasing fibre-matrix interaction the failure mode changed from interfacial failure to matrix failure.
Coconut fibre has been used as reinforcement in low-density polyethylene. The effect of natural waxy surface layer of the fibre on fibre/matrix interfacial bonding and composite properties has been studied by M.Brahmakumar, C. Pavithran and R.M. Pillai [3] by single fibre pullout test and evaluating the tensile properties of oriented discontinuous fibre composites. The waxy layer provided good fibre–matrix bond such that removal of the layer resulted in drastic decrease of the fibre pullout stress, increase of the critical fibre length and corresponding decrease in tensile strength and modulus of the composites. The waxy layer of polymeric nature also exhibited a stronger effect on interfacial bonding than by grafted layer of a C15 long-chain alkyl molecule onto the wax-free fibre. The morphological features of the fibre along with its surface compatibility with the matrix favours oriented flow of relatively long fibres along with the molten matrix during extrusion
Natural fibres (sisal, kenaf, hemp, jute and coir) reinforced polypropylene composites were processed by compression moulding using a film stacking method by Paul Wambua , Jan Ivens, Ignaas Verpoest [4]. The mechanical properties of the different natural fibre composites were tested and compared. A further comparison was made with the corresponding properties of glass mat reinforced polypropylene composites from the open literature. Kenaf, hemp and sisal composites showed comparable tensile strength and modulus results but in impact properties hemp appears to out-perform kenaf. The tensile modulus, impact strength and the ultimate tensile stress of kenaf reinforced polypropylene composites were found to increase with increasing fibre weight fraction. Coir fibre composites displayed the lowest mechanical properties, but their impact strength was higher than that of jute and kenaf composites. In most cases the specific properties of the natural fibre composites were found to compare favourably with those of glass.
Natural rubber is reinforced with untreated sisal and oil palm fibers chopped to different fiber lengths. The effects of concentration and modification of fiber surface in sisal/oil palm hybrid fiber reinforced rubber composites have been studied. Increasing the concentration of fibers resulted in reduction of tensile strength and tear strength, but increased modulus of the composites. Composites were prepared using fibers treated with varying concentrations of sodium hydroxide solution and for different time intervals. The vulcanisation parameters, processability characteristics, and stress–strain properties of these composites were analysed. The rubber/fiber interface was improved by the addition of a resorcinol-hexamethylene tetramine bonding system. The reinforcing property of the alkali treated fiber was compared with that of untreated fiber. The extent of fiber alignment and strength of fiber-rubber interface adhesion were analysed from the anisotropic swelling measurements by Maya Jacob , Sabu Thomas K.T. Varughese [5].
Moisture absorption of natural fiber plastic composites was tested by W. Wang, M. Sain and P.A. Coope [6] Moisture absorption of natural fiber plastic composites is one major concern in their outdoor applications. Traditionally diffusion theory is applied to understand the mechanism of moisture absorption; but it cannot address the relationship between the microscopic structure-infinite 3D-network and the moisture absorption. The purpose of this study is to introduce percolation theory into this field and conduct some preliminary work. First, two new concepts, accessible fiber ratio and diffusion-permeability coefficient, were defined; secondly, a percolation model was developed to estimate the critical accessible fiber ratio; finally, the moisture absorption and electrical conduction behavior of composites with different fiber loadings were investigated. At high fiber loading when accessible fiber ratio is high, the diffusion process is the dominant mechanism; while at low fiber loading close to and below percolation threshold, percolation is the dominant mechanism. The over-estimate of accessible fiber ratio led to discrepancies between the observed and model estimates.
Environmental awareness and an increasing concern with the greenhouse effect have stimulated the construction, automotive, and packing industries to look for sustainable materials that can replace conventional synthetic polymeric fibers. Flavio de Andrade Silva,Nikhilesh Chawla ,Romildo Dias de Toledo Filho [7] found that natural fibers seems to be a good alternative since they are readily available in fibrous form and can be extracted from plant leaves at very low costs. In this work we have studied the monotonic tensile behavior of a high performance natural fiber: sisal fiber. Tensile tests were performed on a microforce testing system using four different gage lengths. The cross-sectional area of the fiber was measured using scanning electron microscope (SEM) micrographs and image analysis. The measured Young’s modulus was also corrected for machine compliance. Weibull statistics were used to quantify the degree of variability in fiber strength, at the different gage lengths. The Weibull modulus decreased from 4.6 to 3.0 as the gage length increased from 10 mm to 40 mm, respectively. SEM was used to investigate the failure mode of the fibers. The failure mechanisms are described and discussed in terms of the fiber microstructure as well as defects in the fibers.
C. Alves, P.M.C. Ferrão,A.J. Silva,L.G. Reis [8] made the idea of introducing making use of natural jute fiber composites in automotive components. Nowadays, the world faces unprecedented challenges in social, environmental and economical dimensions, in which the industrial design has showed an important contribution with solutions that provide positive answers regarding these problems. In particular, due to its relevance, the automotive industry confronts a moment of crises, and based on the ecodesign of products it has been transforming the challenges in opportunities. In this context, the use of natural fiber composites, produced in developing countries, have presented several social, environmental and economical advantages to design “green” automotive components. Thus, this work through LCA method demonstrates the possibility to use natural fibers through a case study design which investigates the environmental improvements related to the replacement of glass fibers for natural jute fibers, to produce a structural frontal bonnet of an off-road vehicle (Buggy). Results pointed out the advantages of applying jute fiber composites in Buggy enclosure.
2.1 OBJECTIVES OF THE RESEARCH WORK
The objectives of the project are outlined below.
Fabrication of Pandanus Odoratissimus fibre polyester matrix composite
with/without alkali treatment.
Evaluation of mechanical properties (tensile strength, flexural,
impact strength etc.
Besides the above all the objective is to develop relatively low cost composites by incorporating cheaper reinforcing phases into a polymeric resin. Also this work is expected to introduce a new class of polymer composite that might find applications in erosive operational situations.
And also to find the properties of the fibre after it is been alkali treated( NaOH).
CHAPTER 3
3. MATERIALS AND METHODS
3.1. Introduction
This chapter describes the details of processing of the composites and the Experimental procedures followed for their characterization and tribological Evaluation. The raw materials used in this work are
1. Pandanus Odoratissimus fibre
2. Polyester resin
3.2.Processing of the Composites
Specimen preparation
Pandanus Odoratissimus fibers are reinforced in unsaturated isophthalic polyester Resin to prepare the composite. The composite slabs are made by conventional compression moulding Technique. Two percent cobalt nephthalate (as accelerator) is mixed thoroughly in isophthalic polyester resin and then 3% methyl-ethyl-ketone-peroxide (MEKP) as hardener is mixed in the resin prior to reinforcement. Composites are made on pure resin with Pandanus Odoratissimus fibre under random orientation(arrangement of fibre in the composites). The castings are put under load for about 3 to 4 hours for proper curing at room temperature. Similar procedure adapted for the preparation of the alkali treated Pandanus Odoratissimus fibre polymer composites.
3.3 characterization of the composites:
3.3.1 Tensile Strength:
The tensile test is generally performed in universal testing machine. The tensile test is performed in UTM. The tension test is generally performed on flat specimens. The test-piece used here was of rectangular type and having dimensions according to the standards.The dimension of the specimen is 165mm*10mm*3mm. A thickness of 3mm is maintained for the treated as well as non-treated composite specimen. A uni-axial load is applied through the ends. The tension test was performed on the samples as per ASTM D638 test standards.
3.3.2 Flexural Strength:
The determination of flexural strength is an important characterization of any Structural material. It is the ability of a material to withstand the bending before Reaching the breaking point. Conventionally a three point bend test is conducted for finding out this material property In the present investigation also the composites were subjected to this test in a testing machine . The photograph of the machine and the loading arrangement for the specimens are shown in Figure. A span of 50 mm was taken samples are taken from each test and the results are averaged. The flexural test is performed in UTM. Flexural test was performed on all the three samples as per ASTM D 790 test standards. Flexural strength can be calculated using this formula :
Flexural Strength = 3PL / 2bh2
Where P= applied central load (N)
L= test span of the sample (m)
b= width of the specimen (m)
h= thickness of specimen under test (m)
Flexural tests monitor behavior of materials in simple beam loading; or transverse beam tests. Specimens are supported as a simple beam, with the compressive load applied at midpoint, and maximum fiber stress and strain calculated. The three point bending flexural test measures bend or fracture strength, yield strength, modulus of elasticity in bending, flexural stress, flexural strain, and flexural stress strain materials response. Flexural strength represents the highest stress experienced within the material at its moment of rupture.
3.3.3 Impact test:
Impact tests are designed to measure the resistance to failure of a material to a suddenly applied force. The test measures the impact energy, or the energy absorbed prior to fracture.The tests are done as per ASTM D 256 using an impact tester .
The standard specimen for ASTM D 256 is 64 x 12 x 3 mm. The most common methods of measuring impact energy are the
Izod test
Charpy test
Charpy test:
While most commonly used on metals, it is also used on polymers, ceramics and composites. The Charpy test is most commonly used to evaluate the relative toughness or impact toughness of materials and as such is often used in quality control applications where it is a fast and economical test. It is used more as a comparative test rather than a definitive test.
The impact test is used to find out the energy required to break the specimen. The un-notched Charpy impact test is conducted to study the impact energy according to the ASTM D256. The un-notched specimens are kept in cantilever position and the pendulum swings around to break the specimen. The impact energy (J) is calculated from the dial gauge, which is fitted on the machine. Five samples are taken for each test and the results are averaged.
3.4 MATERIAL PREPARATION
Required material are Pandanus Odoratissimus fibre, polyester resin. Pandanus Odoratissimus fibre are prepared from Pandanus Odoratissimus plant, Polyester resins are produced by the poly condensation of saturated and unsaturated dicarboxylic acids with glycols.
3.4.1 PANDANUS ODORATISSIMUS PLANT:
Pandanus is a genus of monocots with about 600 known species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. They are classified in the order Pandanales, family Pandanaceae. Often called pandanus palms, these plants are not closely related to palm trees. The botanical family Pandanaceae consists of three genera, namely Sararanga (two species), Freycinetia (175 spp.), and Pandanus (about 600 spp.). The species vary in size from small shrubs less than 1 metre (3.3 ft) tall, to medium-sized trees 20 metres (66 ft) tall, typically with a broad canopy, heavy fruit, and moderate growth rate. The trunk is stout, wide-branching, and ringed with many leaf scars. They commonly have many thick prop roots near the base, which provide support as the tree grows top-heavy with leaves, fruit, and branches. The leaves are strap-shaped, varying between species from 30 centimetres (12 in) to 2 metres (6.6 ft) or more long, and from 1.5 centimetres (0.59 in) up to 10 centimetres (3.9 in) broad.
They are dioecious, with male and female flowers produced on different plants. The flowers of the male tree are 2–3 centimetres (0.79–1.2 in) long and fragrant, surrounded by narrow, white bracts. The female tree produces flowers with round fruits that are also bract-surrounded. The fruits are globose, 10–20 centimetres (3.9–7.9 in) in diameter, and have many prism-like sections, resembling the fruit of the pineapple. Typically, the fruit changes from green to bright orange or red as it matures. The fruit of some species are edible. Pandanus fruit are eaten by animals including bats, rats, crabs, elephants and monitor lizards, but the vast majority of species are dispersed primarily by water.
a) Pandanus plant b) Pandanus flower (fragrance flower)
3.4.1.1 EXTRACTING THE FIBRE:
Fibre is extracted by a process known as decortication, where roots are crushed and beaten by a rotating wheel set with blunt knives, so that only fibres remain. But we have extracted the fibre from the prop roots my hammering. Proper drying is important as fibre quality depends largely on moisture content. Artificial drying has been found to result in generally better grades of fibre than sun drying.
prop roots
3.4.1.2 PANDANUS ODORATISSIMUS FIBRE:
The fibre we have used is extracted from the prop roots after extraction , it is shown in the figures (a) and (b) respectively below..
(a) (b)
3.4.1.3 USES OF PANDANUS ODORATISSIMUS :
Pandan is used for handicrafts. Craftswomen collect the pandan leaves from plants in the wild. Only the young leaves are cut so the plant will naturally regenerate. The young leaves are sliced in fine strips and sorted for further processing. Weavers produce basic pandan mats of standard size or roll the leaves into pandan ropes for other designs. This is followed by a coloring process, in which pandan mats are placed in drums with water-based colors. After drying, the colored mats are shaped into final products, such as place mats or jewelry boxes. Final color touch-ups may be applied.
Pandan (P. amaryllifolius) leaves are used in Southeast Asian cooking to add a distinct aroma to rice and curry dishes such as nasi lemak, kaya ('jam')preserves, and desserts such as pandan cake. Pandan leaf can be used as a complement to chocolate in many dishes, such as ice cream. Fresh leaves are typically torn into strips, tied in a knot to facilitate removal, placed in the cooking liquid, then removed at the end of cooking. Dried leaves and bottled extract may be bought in some places.
Kewra is an extract distilled from the pandanus flower, used to flavor drinks and desserts in Indian cuisine. Also, kewra or kewadaa is used in religious worship, and the leaves are used to make hair ornaments worn for their fragrance as well as decorative purpose in western India.
Throughout Oceania, almost every part of the plant is used, with various species different from those used in Southeast Asian cooking. Pandanus trees provide materials for housing; clothing andtextiles including the manufacture of dilly bags (carrying bags), fine mats or ‘ie toga; food, medication, decorations, fishing, and religious uses.
3.4.2 POLYESTER RESIN
Polyester resins are unsaturated resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Polyester resins are used in sheet moulding compound, bulk moulding compound and the toner of laser printers. Wall panels fabricated from polyester resins reinforced with fiberglass — so-called fiberglass reinforced plastic (FRP) — are typically used in restaurants, kitchens, restrooms and other areas that require washable low-maintenance walls.
Unsaturated polyesters are condensation polymers formed by the reaction of polyols (also known as polyhydric alcohols), organic compounds with multiple alcohol or hydroxy functional groups, with saturated or unsaturated dibasic acids. Typical polyols used are glycols such as ethylene glycol; acids used are phthalic acid and maleic acid. Water, a by-product of esterification reactions, is continuously removed, driving the reaction to completion. The use of unsaturated polyesters and additives such as styrene lowers the viscosity of the resin. The initially liquid resin is converted to a solid by cross-linking chains. This is done by creating free radicals at unsaturated bonds, which propagate in a chain reaction to other unsaturated bonds in adjacent molecules, linking them in the process. The initial free radicals are induced by adding a compound that easily decomposes into free radicals. This compound is usually and incorrectly known as the catalyst. Substances used are generally organic peroxides such as benzoyl peroxide or methyl ethyl ketone peroxide.
Polyester resins are thermosetting and, as with other resins, cure exothermically. The use of excessive catalyst can, therefore, cause charring or even ignition during the curing process. Excessive catalyst may also cause the product to fracture or form a rubbery material.
3.4.3 ALKALI TREATMENT:
There are several different methods for modification of surface energy of the fibre and the polymer. Physical methods like stretching, calendaring and the production of hybrid yams, change the structural and surface properties of the fibre and thereby influence the mechanical bonding in the matrix. Another physicl method used is electric discharge, which will increase the roughness of the fibres and active its surface oxidation leading to the increase in aldehyde groups. It can also generate cross linkings and free radicals.
Oxidizing agents such as Na or Ca and hydrogen peroxides can be used to remove dust and oil from natural fibres. Alkaline treatment with NaOH , known as mercerization , extracts lignin and hemicelluloses, increasing the tensile strength and elongation at break of the composite. In this process the fibres are immersed in 4% solution of NaOH for 1 to 2 hours, followed by continous washing and drying in room temperature.
CHAPTER 4
RESULTS AND DISCUSSION
4.1 INTRODUCTION
This chapter presents the physical and mechanical characterization of the class of polymer matrix composites developed for the present investigation. They are Uni directional sisal fiber reinforced polyester resin composites. Details of processing of these composites and the tests conducted on them have been described in the previous chapter. The results of various characterization tests are reported here. They include evaluation of tensile strength, flexural strength, young’s modulus, impact strength has been studied and discussed.
4.2 COMPOSITE CHARACTERIZATION
4.2.1 Mechanical properties of composites
The characterization of the composites reveals that inclusion of alkali treatment has strong influence on the physical and mechanical properties of composites. The modified values of the properties of the composites under this investigation are presented and compared against the untreated pandanus polyester composite. A gradual increase in impact strength as well as flexural strength with the weight fraction of fiber is noticed. It can be clearly seen that treated fibre shows increase in performance comparing the untreated one. It may be mentioned here that both tensile and flexural strengths are important for recommending any composite as a candidate for structural applications.
4.2.2Tensile Strength:
For untreated pandanus fibre: s-1
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 29.91 Kg
3 Yield Elongation 1.73 mm
4 Break Force 29.9 Kg
5 Break Elongation 1.73 mm
6 Tensile Strength at Yield 49.85 Kg/cm²
7 Tensile Strength at Break 49.85 Kg/cm²
8 % Elongation 1.73 %
For untreated pandanus fibre:s-2
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 16.13 Kg
3 Yield Elongation 2.52 mm
4 Break Force 17.4 Kg
5 Break Elongation 2.73 mm
6 Tensile Strength at Yield 26.89 Kg/cm²
7 Tensile Strength at Break 28.96 Kg/cm²
8 % Elongation 2.73 %
For alkali treated pandannus fibre: s-1
Obtained Results
Sr. No. Results Value
1 Area 0.60 cm²
2 Yield Force 18.03 Kg
3 Yield Elongation 1.31 mm
4 Break Force 18.0 Kg
5 Break Elongation 1.31 mm
6 Tensile Strength at Yield 30.05 Kg/cm²
7 Tensile Strength at Break 30.05 Kg/cm²
8 % Elongation 1.31 %
From the obtained results of the tensile testing of the pandannus fibre it can be noted that there is difference in their properties between the alkali treated and non-treated fibres.
4.2.3 Impact strength:
The impact test was the charpy and izod from the results below it can be noted that there is difference in strength between the alkali treated and non treated pandannus fibres.
4.2.4 Flexural test:
Through the three point bend test the following results were obtained for the pandannus fibre. The graph and result shows the variation in properties between the treated and non-treated fibre.
S.NO SPECIMEN NO JOULES
1 Pandnus Untreated 1 5.794
2 Pandnus Untreated 2.282
3 Pandnus NaohTreat 2 2.020
4 Pandnus NaohTreat 3 0.968
For alkali treated pandannus fibre:s-1
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 5.22 Kg
4 MOD2 DEFLECTION 2.41 mm
5 Stress 1 0.00
6 Stress 2 4.35
7 FLEXURAL MODULES -2175.63 N/mm2
For alkali treated pandannus fibre:s-2
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 6.49 Kg
4 MOD2 DEFLECTION 2.09 mm
5 Stress 1 0.00
6 Stress 2 5.41
7 FLEXURAL MODULES -2703.43 N/mm2
For nontreated pandannus fibre: s-1
Sample details
1 Span Length(mm) 100
2 Thickness (mm) 3
3 Width (mm) 20
4 Ref.Standard ASTMD698
Results
1 MOD 1 FORCE 0.00 Kg
2 MODE 1 DEFLECTION 0.00 mm
3 MOD 2 FORCE 18.18 Kg
4 MOD2 DEFLECTION 5.65 mm
5 Stress 1 0.00
6 Stress 2 15.15
7 FLEXURAL MODULES -7573.85 N/mm2
CHAPTER 5
CONCLUSION
This analytical and experimental investigation on the pandannus odourrattus polymer composites leads to the following conclusions:
This work shows that successful fabrication of a pandannus odourrattus polymer composites with and without alkali treatment by compression moulding technique.
The cheaper natural fibre like pandannus fibre can be used to make an effective fibre polymer composite.
The performance of the non treated pandannus fibre was found to be superior to the treated pandannus fibre.
In flexural test, the non treated pandannus fibre was found to have more strength than the treated pandannus fibre.
From both the impact and tensile test also the non treated pandannus fibre was found to be superior to the treated pandannus fibre..
CHAPTER 6
REFERENCES
[1] K.G. Satyanarayana , K. Sukumaran, A.G. Kulkarni, S.G.K. Pillai, P.K. Rohatg Regional Research Laboratory, Council of Scientific and Industrial Research (CSIR), India Fabrication and properties of natural fibre-reinforced polyester composites
[2] P.J Herrera-Franco and A Valadez-González Centro de Investigación Cientı́fica de Yucatán, A.C., Calle 43 #.130, Col. Chuburná de Hidalgo, C.P. 97200 Mérida, Yucatán, Mexico Mechanical properties of continuous natural fibre-reinforced polymer composites , Received 28 November 2002. Revised 15 June 2003. Accepted 11 September 2003.
[3] M. Brahmakumar, C. Pavithran and R.M. Pillai , Regional Research laboratory (CSIR), Council of Scientific and Ind. Res., Thiruvananthapuram 695 019, Kerala, India ,Received 13 October 2003. Revised 27 July 2004. Accepted 1 September 2004.
[4] Paul Wambua , Jan Ivens, Ignaas Verpoest, Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44 B-3001 Leuven, Belgium , Accepted 21 February 2003.
[5]Maya Jacob , Sabu Thomas K.T. Varughese , School of Chemical Sciences, Mahatma Gandhi University, Priyadarshini Hills P.O. Kottayam, Kerala, 686 560, India Thermal Research Center, KORADI, Nagpur, 441 111, India,Received 8 August 2002. Revised 19 June 2003. Accepted 25 June 2003.
[6] W. Wang, M. Sain and P.A. Coope , Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Canada ,Received 20 July 2005. Accepted 20 July 2005.
[7]Flavio de Andrade Silva,Nikhilesh Chawla ,Romildo Dias de Toledo Filho, Civil Engineering Department, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil ,School of Materials, Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-8706, USA ,Received 23 May 2008. Revised 12 September 2008. Accepted 1 October 2008.
[8] C. Alves, P.M.C. Ferrão,A.J. Silva,L.G. Reis Instituto Superior Tecnico, Rovisco Pais Av., 1049-001 Lisbon, Portugal Universidade Estadual do Sudoeste da Bahia, Praça da Primavera, 40, 45700-000 Itapetinga, Brazil ,Instituto de Artes Visuais, Design e Marketing, D. Carlos I Av., 4, 1200-649 Lisbon, PortugalReceived 12 August 2009. Revised 7 October 2009. Accepted 26 oct.
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