Project Abstract

<p> </p><p>This work has investigated the effect of various chemical treatments on the properties of bagasse<br>fibre for use as filler in unsaturated polyester composite. Bagasse is a natural fibre obtained as a<br>by-product of the sugarcane milling process. As with other natural fibres it has the setback of<br>being hydrophilic; this research tried to explore the use of chemical modification of the fibre<br>surface as a way of remedy. Four different chemicals, namely, Sodium hydroxide, Acetic acid,<br>Acrylic acid and Potassium permanganate were used in carrying out the treatments. Mechanical<br>properties such as tensile strength and modulus, flexural strength and modulus were carried out.<br>The treatments were carried out for 3hours at 70oC except for Sodium hydroxide treatment that<br>was done at room temperature using 2wt% concentration. The Fourier Transform Infrared<br>Spectroscopy (FTIR) analysis of the fibre revealed that the Potassium permanganate treatment<br>had more effect as most of the OH group visible at a peak of around 3400cm-1 were reduced.<br>Also the peaks showing lignin, pectin, and hemicelluose at peaks of 1250-1260cm-1<br>, 1600-<br>1650cm-1<br>, and 1720-1750cm-1<br>respectively were also removed which were all present in the<br>untreated fibre. The Scanning Electron Microscope (SEM) studies of Potassium permanganate<br>treated fibre composite revealed the roughness of the fibre increased as a result of the various<br>chemicals which also showed that Potassium permanganate treated fibre became rougher as<br>compared to the untreated fibre and also had more micropores. The tensile strength of Potassium<br>permanganate treated fibre composite was found to be 77.85MPa as compared to 68.50MPa of<br>the untreated fibre composite. The water absorption level was found to be lower at 2.2%<br>maximum than the untreated fibre composite except for the unsaturated polyester composite<br>which is as expected and was at an average of 5%. The hardness and impact strength were also<br>improved for all chemically treated samples. However, in the case of flexural strength not much<br>effect was seen and in fact the flexural modulus of KMnO4 treated fibre composite dropped to<br>vi<br>21.1MPa and NaOH treated fibre composite was 25.60MPa, Acetic acid (CH3COOH) treated<br>fibre composite 20.91MPa and CH2=CHCO2H treated fibre composite 15.90MPa, all of which<br>were lower than the untreated fibre composite. SEM studies on the composites indicated that<br>higher interaction was found in KMnO4 treated fibre composite although little debonding was<br>observed.</p><p>&nbsp;</p> <br><p></p>

Project Overview

<p> 1.0 INTRODUCTION<br>The use of natural fiber composite is wide and immeasurable in terms of quality, ease of use and<br>good mechanical properties (Nishito et al., 2003). These materials have been widely used in the<br>systems for comfortable driving and to reduce the energy consumption. It is used in automotive,<br>construction, furniture and building industries and also packaging (Satayanarayana et al., 2009;<br>and Inuwa 2013). Natural fiber composites have many advantages over synthetic ones as result<br>of their low cost, recyclability, biodegradability, environmental friendliness, low density, high<br>specific strength and stiffness; excellent absorbance properties and high impact energy<br>absorption (Lu Na et al., 2012; Mohanty et al., 2003; Munawar et al., 2007; and Mwaikambo<br>and Ansell 2002). Environmental issues have resulted in considerable interest in the development<br>of new composite materials based on biodegradable resources (Maldas et al., 2007); the renewed<br>interest of natural fibers was a result of non-renewable problems coupled with the disposal of the<br>synthetic petroleum – based products (Sain et al., 2005). Short fibres are used in rubber<br>compounding to considerably improve processing advantages, improvement in certain<br>mechanical properties and for economic consideration (Gonzalez and Ansell 2009; and Gu<br>2007). The reinforcement of biofibers rubber composites has been well documented by Mark<br>(2011). Though natural fibers have been largely appreciated and appraised, they have their<br>limitations. Their hydrophilic property poses a serious challenge in their effective use and so is<br>not well compatible with polymer matrix which is hydrophobic. To overcome this, the fibre<br>surface has to be modified (Thamae et al., 2007; Dittenber and Gangarao 2012; and Bledzki et<br>al., 1996). The modification could be physical or chemical and has various types, this treatment<br>2<br>process removes non cellulosic substance, e.g. impurities, waxes, pectin, hemicelluloses, lignins<br>which cover the cellulose fibrils and bind these fibrils together (Wu et al., 2000). These<br>contribute to ineffective fibre – matrix interaction and poor surface wetting. Removal of these<br>substances also gives rise to a rougher fibre surface resulting in an increase in surface contact of<br>the fibre and the matrix. This causes an improvement of mechanical interlocking between the<br>polymer and the fibre, leading to enhanced mechanical properties (Sulawan et al., 2012).<br>The vast number of natural fibres used for making composite includes wood, Jute, Bamboo,<br>Sisal, Hemp, Flax, Oil palm, Kenaf, and of recent Bagasse fiber. These fibers were reinforced<br>with various matrixes such as polyester, epoxy, vinyl ester, thermosets, LDPE, phenolformaldehyde e.t.c. (Xue et al., 2006; Maya et al., 2007; Sain et al., 2005; Nural and Ishak<br>2012; Xie et al., 2010; Alvarez and Vazquez 2006; Sever 2010; Seki 2009; Saw et al., 2011 and<br>Srubar et al., 2012).<br>1.1 Composites<br>Composites are materials formed in form of a blend. That is, they contain at least two different<br>materials with varying traits and properties. However, in the blend (composite), their properties<br>are improved. The intent of a composite is to obtain desirable traits, features and characteristics<br>that cannot be obtained when these materials are used individually. The individual materials in<br>the composite still retain their distinct properties. A composite comprises of the reinforcement<br>and the matrix; the reinforcement (that imparts rigidity) is held in place by the matrix which is<br>usually the weaker component (Hull and Clyne 1996).<br>The majority of composites are fibre-reinforced plastics, in which the fibres are embedded in a<br>3<br>matrix. Essentially, stiff composite parts consist of a textile material that is ―frozen‖ into the<br>shape of a polymer matrix that also protects the fibres against degradation due to external factors<br>such as moisture, chemicals, and UV-radiation.<br>The fibres in the matrix may consist of individual fibres or they may have been cross-linked in a<br>specific textile structure, such as a yarn, a woven, knitted fabric or a nonwoven structure.<br>The fibres in the matrix may be oriented in one or more directions. The fibre orientation, length,<br>stiffness and fiber volume fraction will determine to a large extent the mechanical properties of<br>the final composite.<br>1.1.1. Classes of composite<br>Broadly, composites may be classified into three groups on the basis of matrix. They are:<br>Polymer Matrix Composites (PMC)<br>Ceramic Matrix Composites (CMC)<br>Metal Matrix Composite (MMC)<br>Ceramics Matrix Composite (CMC):<br>These may be of low density (although some are very dense). They have great thermal stability<br>and are resistant to most forms of attack (abrasion, wear, corrosion). Although intrinsically very<br>rigid and strong because of their chemical bonding, they are all brittle and can be formed and<br>shaped only with difficulty. These composites are therefore of good strength and stiffness.<br>Metal Matrix Composites (MMC):<br>They are mostly of medium to high density – only magnesium, aluminum and beryllium can<br>compete with plastics in this respect. Many have good thermal stability and may be made<br>4<br>corrosion resistant by alloying. They have useful mechanical properties and high toughness, and<br>they are moderately easy to shape and join. It is largely a consequence of their ductility and<br>resistance to cracking that metals, as a class, became the preferred engineering materials. On the<br>basis of even so superficial a comparison it can be seen that each class has certain intrinsic<br>advantages and weaknesses, although metals pose fewer problems for the designer than either<br>plastics or ceramics.<br>Polymer Matrix Composites (PMC):<br>These are composites in which their matrices are polymers and are the most common. They are<br>of low density. They have good short-term chemical resistance but they lack thermal stability<br>and have only moderate resistance to environmental degradation (especially that caused by the<br>photo-chemical effects of sunlight). They have poor mechanical properties, but are easily<br>fabricated and joined. More so, their manufacturing equipments are simpler and easier to handle<br>and operate. This is further classified into;<br>Fibre – Reinforced Polymer (FRP)<br>Particulate – Reinforced Polymer (PRP)<br>Fibre – Reinforced Polymer (FRP): Common fibre – reinforced composites are composed of a<br>fibre and a matrix. Fibres are used as reinforcements; they serve as the main source of strength<br>while the matrix glues all the fibres together in shape and transfers stresses between the<br>reinforcing fibres. The fibres carry the loads along their longitudinal directions. Sometimes, filler<br>might be added to aid the manufacturing process, imparting special properties to the composites,<br>and / or reduce the cost.<br>Common fibre reinforcing agents include asbestos, carbon/graphite fibres, beryllium, beryllium<br>carbide, beryllium oxide, molybdenum, aluminum oxide, glass fibres, polyamide, natural fibres<br>5<br>etc. similarly, common matrix material includes epoxy, phenolic, unsaturated polyester,<br>polyurethane, polyetheretherketone (PEEK), vinyl esters, etc. epoxy is widely used and has good<br>adhesion properties. However its cost has greatly limited its use.<br>Particulate – Reinforced Polymer (PRP): Particles used for reinforcement include ceramics and<br>glasses such as small mineral particles, metal particles such as aluminum and amorphous<br>materials, including polymers and carbon black. Particles are used to increase the modules of the<br>matrix and to decrease the ductility of the matrix. Reinforcements and matrices can be common,<br>inexpensive materials and that are easily processed. Some of the useful properties of ceramics<br>and glasses include high melting point temperature, low density, high strength, stiffness, wear<br>resistance, and corrosion resistance.<br>Many ceramics are good electrical and thermal insulators. Some ceramics have special<br>properties; some ceramics are magnetic materials; some are piezoelectric materials; and a few<br>special ceramics are even superconductors at very low temperatures. However, ceramics and<br>glasses have one major setback: they are brittle. A good example of a particle reinforced<br>composite is the thread of an automobile tire which has carbon black particles in a matrix of<br>rubber polymer (Owen 2014).<br>1.1.2 Components of a typical composite<br>The major components are:<br>Matrix; and<br>Reinforcement<br>The Matrix: Matrix is continuous, ductile, more flexible and plastic substance. it distributes the<br>load among reinforcing units.<br>6<br>1.1.2.1 Functions of the matrix<br>The matrix binds the fibres together, holding them aligned in the important stressed directions.<br>Loads applied to the composite are then transferred into the fibers, the principal load-bearing<br>component through the matrix; enabling the composite to withstand compression, flexural and<br>shear forces as well as tensile loads. The ability of composites reinforced with short fibres to<br>support loads of any kind is dependent on the presence of the matrix as the load-transfer<br>medium, and the efficiency of this load transfer is directly related to the quality of the<br>fibre/matrix bond.<br>The matrix must also isolate the fibers from each other so that they can act as separate entities.<br>Many reinforcing fibers are brittle solids with highly variable strengths. When such materials are<br>used in the form of fine fibers, not only are the fibers stronger than the monolithic form of the<br>same solid, but there is the additional benefit that the fiber aggregate does not fail<br>catastrophically. Moreover, fibre bundle strength is less variable than that of a monolithic rod of<br>equivalent load-bearing the ability. But these advantages of the fibre aggregate can only be<br>realized if the matrix separates the fibres from each other so that cracks are unable to pass<br>unimpeded through sequences of fibres in contact, which would result in completely brittle<br>composites.<br>The matrix should protect the reinforcing filaments from mechanical damage (eg. abrasion)<br>and from environmental attack. Since many of the resins which are used as matrices for glass<br>fibres permit diffusion of water, this function is often not fulfilled in many GRP materials and<br>the environmental damage that results is aggravated by stress. In cement the alkaline nature of<br>7<br>the matrix itself is damaging to ordinary glass fibres and alkali-resistant glasses containing<br>zirconium have been developed in an effort to counter this.<br>For composites like MMCs or CMCs operating at elevated temperature, the matrix would need<br>to protect the fibres from oxidative attack.<br>A ductile matrix will provide a means of slowing down or stopping cracks that might have<br>originated at broken fibres: conversely, a brittle matrix may depend upon the fibres to act as<br>matrix crack stoppers.<br>Through the quality of its ‗grip‘ on the fibres (the interfacial bond strength), the matrix can also<br>be an important means of increasing the toughness of the composite.<br>By comparison with the common reinforcing filaments most matrix materials are weak and<br>flexible and their strengths and moduli are often neglected in calculating composite properties.<br>But metals are structural materials in their own right and in MMCs their inherent shear stiffness<br>and compression rigidity are important in determining the behavior of the composite in shear and<br>compression. The potential for reinforcing any given material will depend to some extent on its<br>ability to carry out some or all of these matrix functions, but there are often other considerations.<br>1.1.2.2 Reinforcement: Discontinuous, hard and firm component<br>Styles of reinforcements<br>Many reinforcing fibres are marketed as wide, semi-continuous sheets of ‗prepreg‘ consisting of<br>single layers of fibre tows impregnated with the required matrix resin and flattened between<br>paper carrier sheets. These are then stacked and allowed to cure with time, the orientations of<br>each ‗ply‘ being arranged in accordance with design requirements, and hot pressed to consolidate<br>8<br>the laminate. This process is able to cope with curved surfaces, provided the degree of curvature<br>is not too great, but there may be a possibility of local wrinkling of the fibres when prepregs are<br>pressed into doubly curved shapes.<br>One means of overcoming this problem is to use the reinforcement in the form of a woven cloth.<br>Many of the fine filamentary reinforcing fibers like glass, carbon and Silicon can be readily<br>woven into many kinds of cloths and braids, the fibres being effectively placed by the weaving<br>process in the directions required by the designer of the final composite structure.<br>In simple designs, this may call for nothing more elaborate than an ordinary plain weave or satin<br>weave, with fibres running in a variety of patterns but in only two directions, say 0° and 90°, but<br>weaving processes to produce cloths with fibres in several directions if the plane of the cloth are<br>readily available. Fibres of different types have also been intermingled during the weaving<br>processes to produce mixed-fibre cloth for the manufacture of fabrics.<br>We have considered expensive raw materials, and it is often only the fact that the overall cost of<br>a product may nevertheless be lower than a manufactured composite, conventional materials by<br>more costly processes that makes a competing product made from composites design solution<br>gives an attractive alternative. Thus, although large quantities of glass fibres are supplied in<br>chopped form for compounding with both thermoplastic and thermosetting matrix polymers, it<br>may not seem economical to chop the more expensive types of reinforcement. Nevertheless,<br>there are some advantages in using even these fibers in chopped form, provided they can be<br>arranged in the composite in such a way as to make good use of their intrinsically high strengths<br>and stiffness. The process for producing both chopped fibres, like glass and carbon, and naturally<br>short filaments, like whiskers or asbestos fibres, in the form of prepreg sheets with fibres that<br>were very well aligned in either unidirectional or poly-directional patterns is advantageous.<br>9<br>These prepregs also have excellent ‗drapability‘ and can be used to form complex shapes, long as<br>the short fibres are well above some critical length, which for carbon, for example, may be of the<br>order of only a millimeter, they are able to contribute a high fraction of the intrinsic properties to<br>the composite without the loss that occurs with woven reinforcements as a result of the out-ofplane curvature of the fibres<br>Composite materials are usually classified by the type of reinforcement they use. For example, in<br>a mud brick, the matrix is the mud and the reinforcement is the straw. Common composite types<br>include random-fiber or short-fiber reinforcement, continuous-fibre or long-fibre reinforcement,<br>particulate reinforcement, flake reinforcement, and filler reinforcement.<br>In the composite material, the structural reinforcement is held in place by matrix. In the case of<br>fibre reinforced polymer (FRP) composites, structural fibre is surrounded by a matrix adding<br>rigidity. Most often this matrix is a thermoplastic or a thermosetting resin. A matrix alone is not<br>structural and brittle while the reinforcement alone is flimsy. But together, they form a strong<br>composite. A matrix is therefore the resinous phase of a reinforced plastic material which the<br>fibres or filaments of a composite are embedded.<br>Fibre-matrix interface is the area which separates the fibre from the matrix and differs from them<br>chemically, physically and mechanically. This region in most composite materials has a finite<br>thickness because of diffusion and / or chemical reactions between the fibre and the matrix.<br>1.1.3 Benefits of composites<br>a. Light weight: In comparing composites to materials like ceramic, metal, and wood; then,<br>composite can be said to be very light typically a composite material will weigh ¼ that of<br>a steel structure of the same strength. Hence, a car or motorcycle made from composite<br>10<br>will weigh much lesser that when made from steel or other alloy metals. It has also been<br>proven that fuel consumption is greatly reduced.<br>b. High strength: One major reason of blending materials is to obtain certain desired<br>characteristics based on end use. Increase in strength is one of such and composite<br>materials are extremely strong, particularly per unit weight. Composite materials like<br>Aramid and S-glass which are used widely for making body armor. Soldiers have more<br>protection from blast and fire threats due to high strength composite materials.<br>c. Corrosion and chemical resistance: Composites are highly resistant to chemicals and will<br>never rust or corrode. This explains the much use of composites in marine applications,<br>they were also among the very first to discover composite as salt water is corrosive and<br>can lead to rusting. Composite is therefore a big advantage to the marine industry.<br>d. Elastic: Fibre reinforced composites have excellent elastic properties. When metals or<br>steel are bent, they yield but in the case of composite, they almost immediately snap back<br>into place a phenomenon that is ideal for springs. Thus, composites are used in car leaf<br>springs.<br>e. Non-conductive: Certain composites are non-conducting. For example, ladders are meant<br>to be strong and rigid but not conduct electricity when made from composite, but those<br>made from aluminum can conduct electricity. Although, most electrical companies such<br>as the Power Holding Company of Nigeria (PHCN) still use aluminum which is not safe<br>for workers, a number of developed countries now use composite ladders which are safer.<br>11<br>1.2 Fibres<br>These are flexible macroscopically homogeneous body having a ratio of length to width and a<br>small cross-section.<br>Fibres are classified as either natural or synthetic<br>Natural fibres: These can be mineral based e.g. asbestos; animal based e.g. wool, silk, mohair,<br>e.t.c or vegetable which are classified as part of the plant from which the fibre is obtained e.g.<br>seed hairs (cotton, kapok), stem or bast fibres (hemp, jute, ramie, Kenaf), fruit (coir) and leaf<br>(sisal, pineapple, palm, henequen, bagasse). Ugbolue (1999).<br>1.2.1 Agricultural fibres<br>There is an increasing interest in using agricultural fibres for building components, either to<br>complement or replace wood. Many of these lingocellulosics have been used to successfully<br>produce particleboards, fibreboards, inorganic bonded products, and other building components.<br>Building components made from agricultural materials fall into the same product categories as<br>other wood-based composition products. Low-density insulation boards, medium-density<br>fibreboards, hard-boards, particleboard, and other building system components, such as walls<br>and roofs, are being produced. Binders may be synthetic thermosetting resins, modified naturally<br>occurring resins like tannin or lignin, starches, thermoplastics, inorganic, or no binder at all.<br>There seems to be little restriction to what has been tried and what may work.<br>1.2.2 Sugarcane bagasse fibre<br>Sugarcane, a renewable agricultural resource from which bagasse fibre is obtained is largely<br>grown in three major countries namely; Brazil, India, and China in decreasing order. It is also<br>12<br>grown in other parts of the world which includes northern Nigeria but in relatively small<br>quantities as compared to the above mentioned countries. From literature, there are over 10<br>varieties of sugarcane grown around the world identified using numbers, each with its<br>distinguishing characteristics ranging from color, size, taste, time of maturity, crystallinity,<br>tensile and flexural properties, to soil adaptability.<br>Bagasse is an organic waste product produced during the pressing of sugar cane to extract sugar<br>and the extraction of juice from sorghum that is used to make alcoholic beverages. While it was<br>originally seen to have no commercial value, it is now used as a source of cellulose to make<br>ethanol fuel, shaped into disposable table ware, paper production in nations with climates where<br>only few trees can be grown; it is also inculcated into building materials. Using bagasse in this<br>manner is seen as beneficial to the environment and as a significant reduction in the waste<br>stream. In some other instances, bagasse is burned to supply heat to the sugar refining operation;<br>some is returned to the fields; and finds their way into various panel products. Bagasse is<br>composed of fibre and pith. The fibre is thick walled and relatively long (1 to 4mm). It is<br>obtained from the rind and fibro vascular bundles dispersed throughout the interior of the stalk.<br>For the best quality bagasse fibre and particle boards, only the fibrous portion is utilized.<br>Another name for bagasse is megass, from a root term that originally meant ―rubbish‖. Instead of<br>creating air pollution by burning it, however, new uses for it continue to flourish daily. It has<br>become an essential ingredient in pressed construction materials used in the building trade, in the<br>manufacture of acoustical tile, and as a source fibre in animal feed. Brazil has the world leading<br>economy for bagasse production from sugarcane, followed closely by India. It was estimated in<br>2004 that Brazil produced 12% of its own electricity needs by using it to generate alchohol–<br>based fuel such as ethanol, or through burning the waste in pellet form directly. The Brazilian<br>13<br>Sugarcane Industry Association (UNICA) noted in 2011 that the harvest was projected to be<br>around 595.89million tons which is a 10% increase from the previous year.<br>1.3 Statement of the Research Problem<br>The good potential of natural fibres as a suitable substitute for synthetic fibres in reinforced<br>composites is now in vogue. Synthetic fibres are non-biodegradable, expensive to process, and<br>require expatriates in handling equipments. A number of natural fibre advantages have been<br>identified; these include: low weight, environmental friendliness, non-toxicity, availability, low<br>cost, and non-requirement of technical know-how to obtain the fibres. However, its hydrophilic<br>nature which creates poor adhesion between the fibre and polymer matrix is one factor that has<br>limited its full utilization – hence the research problem. Fibre modification using chemical or<br>physical treatment has been developed as a way of remedy; although a number of these<br>treatments exist some are more compatible to certain fibers than others (Haque et al., 2010). It<br>would therefore be considered in this work the readily availability of the fibre of choice<br>(Bagasse) and polymer to be used for the production of this composite and to see how best or to<br>what extent the fibre–matrix interphase can be improved by carrying out various chemical<br>treatments on the fibre and observing its effect on the finished composite produced.<br>14<br>1.4 Research Aim and Objectives<br>Aim:<br>The aim of this study is to state the likely suitable chemical modification method for the variety<br>of bagasse fibre used as far as the four chemical used (acetic acid, acrylic acid, sodium<br>hydroxide, and potassium permanganate) is concerned.<br>Objectives:<br>i. To utilize waste sugarcane as a reinforcement in composite production.<br>ii. To evaluate the effect of different chemical treatments of the bagasse fibre by carrying<br>out SEM studies.<br>iii. To prepare the fibre-polymer reinforced composite using the hand lay-up technique and<br>study its mechanical properties.<br>iv. To evaluate its water absorption properties as a function of immersion time.<br>1.5 Justification<br>Although a hand full of research has been carried out on fibre reinforced composites from the<br>view of improving the hydophobicity of the fibre through fibre modification; this research used<br>four chemicals for its treatments as oppose to the usual one or two. The treatment ought to<br>improve adhesion, compatibility and interaction between the fibre and the polymer matrix.<br>Sugarcane is readily available hence the fibre is in abundance. This research is aimed at<br>15<br>exploring the possibilities and opportunities available for the use of Bagasse fibre – polymer<br>composite for use in place of ply woods in construction and other building applications.<br>Unsaturated polyester has been chosen as the polymer because of not just its availability but its<br>low cost and compatibility. In this part of the world the sugar industry is growing and a lot of<br>sugar cane stem from which Bagasse fibre is obtained is left as waste. The world is campaigning<br>for zero waste as much as possible. The idea is from “waste to wealth”.<br>1.6 Scope of the Study<br>The study is limited to the following areas:<br>i. Analysis of the physical properties of only Bagasse fibre after chemical treatments.<br>ii. FTIR analysis of the treated fibres.<br>iii. SEM studies of fibres and also of the produced composites.<br>iv. Analysis of the mechanical properties of the composite. <br></p>