Preparation and Testing of Composites using Waste Groundnut Shells and Coir Fibres

ScienceDirect ScienceDirect Available online at www.sciencedirect.com ScienceDirect ScienceDirect Procedia Manufacturing 20 (2018) 91–96 www.elsevier.com/locate/procedia 2nd International Conference on Materials Manufacturing and Design Engineering Preparation and Testing of Composites using Waste Groundnut Shells and Coir Fibres Onkar V. Potadara,*, Ganesh S. Kadama a Department of Mechanical Engineering, SIES Graduate School of Technology, Nerul, Navi Mumbai 400706, Maharashtra, INDIA Abstract Composite materials are now-a-days replacing the traditional materials because of its superior properties such as high tensile strength, low thermal expansion and high strength-to-weight ratio. Natural fibre composites such as groundnut shell polymer composites and coir composites have become more attractive due to their high specific strength, light weight and biodegradability. This work attempts to study particulate natural fiber based epoxy composites. It is concerned with the preparation and testing of composite materials from groundnut shell fibres and coir fibres along with binder and epoxy resins. The groundnut shells are chemically washed, cleaned and then dried in sunlight. The dried shells are then grinded to particle sizes of 1 mm, 1.5 mm, 2 mm and the epoxy resins are added in 70:30 ratio by weight to the fibres in a 12 mm thick mould and different flat square-shaped composites are obtained. Specimens of different particle sizes are cut into standard dimensions as per ASTM for different mechanical and moisture absorption tests. The results thus obtained are relatively compared between groundnut shell and coir fiber composites so as to suggest suitable applications. In general, the coir fibre composites are found to be comparatively better than groundnut fibre composites particularly considering the mechanical properties. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Manufacturing and Design Engineering. Keywords: Green composites; bio-fibres; composites; matrix; mechanical testing. 1. Introduction A composite material is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the * Corresponding author. Tel.: +91-8291186426. E-mail address: onkarhubli@gmail.com 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Materials Manufacturing and Design Engineering. 10.1016/j.promfg.2018.02.013 92 Onkar V. Potadar et al. / Procedia Manufacturing 20 (2018) 91–96 individual components. Composites, in most cases, are prepared by reinforcing fibres with matrix resins. The reinforcements can be in the form of long or continuous fibres, particulates or whiskers, and the matrix materials usually used are metal, plastics or ceramics. The present work is focused on utilization of waste bio-fiber like groundnut shell and jute fiber for the preparation of composites. Various research groups have worked on ground-nut shell and jute fibres in the past. Morphology of modified surfaces in case of jute fabrics examined using scanning electron microscopy and fourier transformed infrared spectroscopy revealed improved upper surfaces for better adhesion with the matrix [1]. Study of the effect of calcium carbonate on the mechanical properties of groundnut shell powder based composite had been carried out. The experimental investigation on mechanical properties of tensile strength and flexural strength for groundnut shell powder/calcium carbonate/vinyl ester composites showed that the material is greatly influenced by the groundnut shell powder/calcium carbonate composition [2]. Coconut shell reinforced composite was prepared by compacting low density polyethylene matrix with 5%-25% volume fraction coconut shell particles and the effect of the particles on the mechanical properties of the composite produced has been investigated [3]. Another work was carried out to develop a polymer matrix composite (epoxy-resin) using coconut shell powder (CSP) in different particle sizes and reinforcing in different volume and further evaluated its tensile strength, flexural property and hydrophilic behavior along with engineering application of resulting composites [4]. In the work carried out by Berhanu et al. [5], jute fibre-polypropylene reinforced composites were prepared using compression molding process. The investigation stated that the 40 wt% jute fiber reinforced PP composite exhibited the highest tensile strength. However, the tensile strength decreased with further increase in the wt% of jute fiber reinforcement. The cost of production and energy consumption in conventional fibres is more than that of natural fibres. Due to this, natural fibres are preferred over conventional or man-made fibres [6]. The existing research in our considered literature primarily lacks the study regarding potential of these new materials to replace standard materials in use today, and also the cost saving thus achieved. For an agrarian nation like India where groundnut, coconut, jute and bamboo production is large and these products are available in plenty and at very cheap rates, the economic feasibility and potential for such new materials is possibly high and the applications are promising from composites point-of-view. In this work, we intend to explore the potential of natural fibre composites through manufacturing and testing of the same in view as replacement to many commercially used alternatives today. 2. Experimental work 2.1. Mould Preparation Mould preparation is designing the mould according to the size of the specimen required. Mild steel was selected as the mould material because of its fair hardness, shock absorption capability and easy availability. Four supporting bars of dimensions 163×12×12 mm were used to prepare an enclosure for the mould as shown in Fig. 1. Bolting the supporting bars to the mould facilitates easy removal of the rectangular composite obtained. Fig. 1. (a) first picture; (b) second picture. Onkar V. Potadar et al. / Procedia Manufacturing 20 (2018) 91–96 93 2.2. Fiber Preparation The strength of the composites depends significantly on preparation of the fibres. The ground nut shells and coir husks were collected from the local market and were washed with water to take away sand and other impurities. The washed shells were treated with 10% sodium hydroxide (NaOH) solution to purge minor impurities. The fibres were then again washed with water until the NaOH residue was totally removed. Now that the fibres were cleaned thoroughly, they were again solar dried for 24 hours. Thus the fibres were ready for final use as reinforcement in the composites. Subsequently, the fibres were grinded to smaller sizes and were sieved through meshes of 1 mm, 1.5 mm and 2 mm to obtain fine uniform shapes and get different sizes of groundnut fiber and coir fiber. These three different fine sieved particles were used as reinforcement materials in the epoxy polymer matrix. The hand lay-up process is used for preparation of specimen. Before starting the actual laminating process, the mould surface has to be cleaned and prepared with a suitable mold release agent, which must be properly applied over mould for easy removal of specimen. 2.3. Matrix material Araldite LY-556 and Hardener HY-951 is used as matrix material. Araldite LY-556 is a liquid, unmodified epoxy resin of medium viscosity which can be used with various hardeners for making glass fiber/natural fiber reinforced composites. Hardener HY-951 is a low viscosity room temperature curing liquid hardener. It is commonly employed for hand lay-up applications. Being rather reactive, it gives a short pot life and rapid cure at normal ambient temperatures. 2.4. Preparation of composite For preparing matrix, resin and hardener were mixed in ratio of 10:1 and poured into a small beaker and the mixture was stirred properly. Care was taken that air bubbles were not formed while adding the resin. Some amount of that mixture is then poured in mould initially with help of brush and then we added some amount of raw material. Again we repeated same procedure slowly and constantly mixed them with help of brush. After that pressure was applied using hand roller so that mixture will be pressurized evenly and care was taken that all corners of mould will be filled properly. Compression is done carefully to avoid built up of air gap within the sample. The hammering was done to give a flat surface to the specimen, by keeping a load on top of the mould. The overall ratio of matrix material and raw material is as given in Table 1. Table 1. Ratio of matrix and fibre (raw material) [11] Specimen No. Matrix Fiber (Particle size) 1 70% wt 30% wt (1 mm) 2 70% wt 30% wt (1.5 mm) 3 70% wt 30% wt (2 mm) This same procedure was repeated for coir fiber too. These set-ups were allowed to cure for around 15 hours at room temperature. After 15 hours, firstly supporting bars were removed. Hammer and chisel were carefully used for separating the rectangular composite from the mould. After separating the rectangular specimen of size 163×63×6 mm, it was cut with the help of hand-operated saw machine to obtain specimens as per ASTM D638-03 testing standard for tensile testing of composites as shown in Fig. 1a. Specimens for 3-point bending test were also cut with the help of hand-operated saw machine to obtain specimens as per ASTM D638-03 testing standard for flexural (bending) testing of composites as shown in Fig. 2b. 94 Onkar V. Potadar et al. / Procedia Manufacturing 20 (2018) 91–96 (a) (b) Fig. 2. Standard specimens for (a) Tensile test; (b) Bending test 2.5. Testing for mechanical strength and moisture absorption The testing for mechanical strength consists of testing the tensile strength and the flexural (bending) strength. Thus for measuring the same, the standard setup of Universal testing machine available in strength of materials lab is used. The experimental set-up during tensile and flexural testing of specimens is shown in Fig. 3a and Fig. 3b respectively. Further for moisture absorption test, the sample was placed in water at room temperature. After every 24 hours, the sample was removed, checked for weight and then again placed in the water beaker. This process was repeated for 7 days and the percentage increase in weight was calculated. The percentage of water absorbed was thus computed for specimens of grain sizes 1 mm, 1.5 mm, 2 mm of groundnut shell and coir fiber respectively. (a) (b) Fig. 3 Experimental test set-up: (a) Tensile testing, and (b) Flexural testing 3. Results and Discussion Fig. 4 shows the results of mechanical testing and moisture strength for groundnut fibre composites, while Fig. 5 shows the same for coir fibre composites. More or less similar trends are observed in case of both, groundnut fibre composites as well as coir fibre composites Considering the tensile strength of groundnut fibre composites (Fig. 4a), it is observed that the tensile strength decreases with increase the grain size of the particulate groundnut fibre. However for the flexural strength of groundnut fibre composites (Fig. 4b), it is seen that the flexural strength first decreases with increase in the grain size from 1 to 1.5 and then further increases with increase in the grain size from 1.5 to 2. Also considering the moisture absorption of groundnut fibre composites (Fig. 4c), it is observed that the rate of moisture absorption continually Onkar V. Potadar et al. / Procedia Manufacturing 20 (2018) 91–96 95 increases with an increase in the grain size of the particulate groundnut fibre. Thus the best from the manufactured groundnut fibre composites consist of basically the composite with 1 mm grain size of the particulate groundnut fibre as it gives the highest mechanical properties in terms of high tensile strength and high flexural strength, while the lowest moisture absorption which obviously needs to be always on the lower side for better shelf-life. (a) (b) (c) Fig. 4 Results for groundnut fibre composites: Grain size vs. (a) Tensile strength, (b) Flexural strength, and (c) Moisture absorption Further focusing on the tensile strength of coir fibre composites (Fig. 5a), it is observed that the tensile strength decreases with increase in the grain size of the particulate coir fibre. However for the flexural strength of coir fibre composites (Fig. 5b), it is seen that the flexural strength first decreases by a larger magnitude with increase in the grain size from 1 to 1.5 and then further appreciably increases with increase in the grain size from 1.5 to 2. Also considering the moisture absorption of coir fibre composites (Fig. 5c), it is observed that the rate of moisture absorptions continually increases with an increase in the grain size of the particulate coir fibre. Thus the best from the manufactured coir fibre composites consist of basically the composite with 1 mm grain size of the particulate coir fibre as it gives the highest mechanical properties in terms of high tensile strength and high flexural strength, while the lowest moisture absorption. (a) (b) (c) Fig. 5 Results for coir fibre composites: Grain size vs. (a) Tensile strength, (b) Flexural strength, and (c) Moisture absorption 4. Conclusions The experimental investigation leads to the following conclusions.  Both, the grain size as well as the type of fibre significantly influence the mechanical properties as well as moisture absorption capabilities of concerned composites. 96 Onkar V. Potadar et al. / Procedia Manufacturing 20 (2018) 91–96     The highest tensile strength was found for a particulate grain size of 1 mm for both, groundnut fibre composites as well as coir fibre composites; however coir fibre composites had comparatively higher tensile strength than groundnut fibre composites. When it comes to higher flexural strength, again the particulate grain size of 1 mm provided the same for both, groundnut fibre composites as well as coir fibre composites; also coir fibre composites had comparatively flexural tensile strength than groundnut fibre composites. Considering the moisture absorption capability, the particulate grain size of again 1 mm provided the same at lowest rate for both, groundnut fibre composites as well as coir fibre composites; but groundnut fibre composites revealed lower moisture absorption capability than coir fibre composites thus making it more suitable. Overall, coir fibre composites are comparatively better than groundnut fibre composites as far as mechanical properties are concerned. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] M.K. Hossain, M.W. Dewan, M.V. Hosur, S. Jeelani, Physical, Mechanical, and Degradability Properties of Chemically Treated Jute Fiber Reinforced Biodegradable Nanocomposites, Journal of Engineering Materials and Technology, 133/4 (2011), doi:10.1115/1.4004690. R. Pragatheeswaran, S. Senthil Kumaran, Mechanical behaviour of groundnut shell powder/calcium carbonate/vinyl ester composite, International Journal of Current Engineering and Scientific Research, 2 (2015) 28-31. J. 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