Rajesh Ghosh et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 4, Issue No. 1, 089 - 091
Effect of fibre volume fraction on the tensile strength of Banana fibre reinforced vinyl ester resin composites Rajesh Ghosh*
Assistant Professor, Department of Mechanical Engineering Gitam University,Visakhapatnam, India rajesh_ghosh@yahoo.com
G. Reena
System Analyst, Onsite ETL Coordinator, Mahindra Satyam, Singapore. g.reena0001@gmail.com
Bh.Lakshmipathi Raju
Professor, Department of Mechanical Engineering, Andhra University, India. ramakrishna_a@yahoo.com
Thermoset resin commonly used in engineering applications is epoxy. Epoxy has better mechanical properties but it is costly. The thermoplastics offer recycling possibilities whereas the thermosets achieve improved mechanical properties [6]. Polyester resins are low cost materials, but have inferior mechanical properties. Vinyl ester resins make a compromise between the above two limits. They have properties comparable with epoxy, but are available at low cost. Plant fiber polymer composites are used in interior parts of automobiles [7, 8].
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Abstract—Natural fibre reinforced polymer composites are being worked upon for various engineering applications. Various natural fibres such as jute, sisal, palm, coir and banana are used as reinforcements. In this paper, banana fibres have been used as reinforcement in Vinyl ester resin matrix. The influence of different volume fraction of the fibres in the composite is studied. It is seen that with the increase in the fibre fraction, the tensile strength have increased after an initial dip. At 35% of fibre volume fraction, an increase of 38.6% in tensile strength is noted. The specific tensile strength increased by 65%. With increase in mechanical properties it can be deduced that banana fibre can be reliably reinforced with vinyl ester resin which may be used in engineering utilities.
Assistant Professor, Department of Mechanical Engineering, Gitam University, India. bhlpr19@rediffmail.com
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Dr. A. Rama Krishna
Keywords- fibre volume; banana; vinyl ester; composites; mechanical properties;
I.
INTRODUCTION
Much work is done in the application of natural fibre as reinforcement in polymer composites. In India, banana is abundantly cultivated. Banana fiber can be obtained easily from the plants which are rendered as waste after the fruits have ripened. So banana fiber can be explored as a potential reinforcement. Jute fiber composite have better strength than wood composites as reported by Gowda et al [1]. Laly et al [2] have reported the optimum content in banana fiber in polyester composite to be 40%. Sreekumar et al [3] have investigated effect of fiber content in polyester composites and have reported 40% volume fraction to show maximum tensile strength. Henequen, palm and sisal fibre all have nearly the same kind of tensile, chemical and physical properties as reported by Belmares et al [4]. Pothan et al [5] researched on reinforced polyester composites with short banana fiber. It is shown that 30 mm fiber length gave maximum tensile strength and 40mm fiber length shows maximum impact strength.
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Researchers have reported that the mechanical properties can be improved by appropriate surface treatments [9, 10]. With the increase in surface area, the cellulose micro fibrils get exposed, which in turn improves the wettability and impregnation [11]. In the present work, the fibres were treated with NaOH to increase the wettability. Banana fibres are used as reinforcement in vinyl ester resin and the effect of fibre volume fraction in the composite is studied. II.
MATERIALS AND METHODS
A. Chemical treatment of fibers Banana fibers as shown in fig1, were procured from TamilNadu – India. The fibers were then treated with 5% NaOH solution for 4 hours. The fibers are then washed thoroughly with distilled water. Fibers are then put in a oven for 24 hours at 80 oC to remove any traces of moisture.
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Fig1. Untreated banana fiber.
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Rajesh Ghosh et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 4, Issue No. 1, 089 - 091
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RESULTS AND DISCUSSION
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There is a decrease in the density of the composite with the increase in the fiber volume fraction. This can be attributed to the fact that the density of fiber is lower than the resin. Fig3 shows the variation of mean tensile strength with the increase in percentage of fiber volume fraction. There is a dip in the mean tensile strength during the initial stages of fiber loading. This shows that the load is not properly transmitted to the fibers. The sole purpose of reinforcement is not properly served at lower volume fractions. But as the fiber volume percentage increases from 10%, the mean tensile strength also increases. At 35 % of fiber volume, the tensile strength is increased by 38.6%. This should be because of the increased bonding between the fiber and the matrix. The load sharing is easily transmitted to the fibers. Fig4 shows the tensile modulus of the
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Fig.4 Effect of fibre volume fraction on tensile modulus modulus with 65% increase at 35% fiber volume fraction. The graphs of specific tensile strength (fig.5) and specific tensile modulus (fig.6) plotted against fiber volume fraction show an increasing trend in accordance with the tensile strength and tensile modulus. 0.16 0.14
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Fig.5 Effect of fibre volume fraction on specific tensile strength.
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III.
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D. Tensile test Tensile test is done according to ASTM D638 with a gauge length of 50 mm. Tests are carried out in Hounsfield tensometer model –H20 KW. The cross head speed is 1 mm/min.
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C. Preparation of the composite The composites are made by hand lay-up technique. As shown in fig2. The mould used for the composite is made of mild steel with plywood sheet placed in the inner surface. A debonding agent is applied on the plywood sheet and the composite specimen is casted in the mould. The inner cavity dimension of the mould is 200 mm x 200 mm x 10 mm. The upper plate is bolted to the mould and the setup is left to cure for 24 hours at room temperature. The composite plate so formed is then oven cured for 24 hours at 80 oC. Specimens are cut for testing as per ASTM standards. Fig2. The mould.
composite plotted against percentage fiber volume fraction. The graph shows a near linear increase in the tensile
Tensile modulus (GPa)
B. Matrix Vinyl ester resin is obtained from Ecmas India pvt ltd under the trade name of Ecmalon 9911. It appears as a clear yellow color liquid with viscosity of 400 cps and specific gravity of 1.05. The cast resin has a tensile strength of 70 MPa and tensile modulus of 3200 MPa.
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Fig.3 Effect of fibre volume fraction on tensile strength
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Fig.6: Effect of fibre volume fraction on specific tensile modulus
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Rajesh Ghosh et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 4, Issue No. 1, 089 - 091
CONCLUSION
There is an improvement in the tensile properties of the banana fiber – vinyl ester resin composites. At 35% of fiber volume fraction, the tensile strength is increased by 38.6% and 65% increases in tensile modulus. At lower volume fractions of banana fiber, the strength of the composite specimen is reduced when compared with the virgin resin. Banana fiber having high specific strength makes a lightweight composite material and can be used to make light weight automobile interior parts.
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[2]
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[3]
T.M.Gowda, A.C.B.Naidu and R.Chhaya, Some Mechanical Properties of Untreated Jute Fabric-Reinforced Polyester Composites, J. Composites Part A: Applied Science and Manufacturing, 30(3)(1999), pp.277–284. A.Laly Pothan, Zachariah Oommenb and Sabu Thomas, Dynamic Mechanical Analysis of Banana Fiber Reinforced Polyester Composites, Composites Science and Technology, 63(2)(2003), pp.283–293. P.A.Sreekumar, Pradeesh Albert, G.Unnikrishnan, Kuruvilla Joseph and Sabu Thomas, Mechanical and water sorption studies of ecofriendly
banana fiber reinforced polyester composites fabricated by RTM. J. App. Poly. Sci, 109, (2008) pp.1547-1555. [4] H.Belmares, A.Barrera and M.Monjaras, New composite materials from natural hard fibers. Part 2: Fatigue studies and a novel fatigue degradation model. Ind Eng Chem Prod Res Dev, 22(1983) pp.643–52. [5] L.A.Pothan, T.Sabu, and Neelakantan, Short Banana Fiber Reinforced Polyester Composites: Mechanical, Failure and Aging Characteristics, J. Reinforced Plastics and Composites, 16(8)(1997) pp.744–765. [6] S.Padma Priya and S.K.Rai, Mechanical Performance of Biofiber/Glassreinforced Epoxy Hybrid Composites. Journal of Industrial Textiles 35(3) (2006) pp.217-226. [7] S.Panthapulakkal, M.M.Sain, Injection molded short hemp fiber/glass fiber reinforced polypropylene hybrid composites – mechanical, water absorption and thermal properties. Journal of applied polymer science, 103(2007) pp. 2432-2441 [8] B.Reck, J.Turk, Thermally curable aqueous acrylic resins – a new class of duroplastic binders for wood and natural fibers. Die Angewandte Makromolekulare Chemie, 272(1999) pp.5-10. [9] S.H.Aziz, M P.Ansell, The effect of alkanization and fiber alignment on the mechanical and thermal properties of kenaf and hemp bast fiber composites: part 1 – polyester resin matrix. Composites science and technology,64(2004) pp.1219 – 1230 [10] A.Bessadok, S.Marais, S.Roudesli, C.Lixon, M.Metayer, Influence of chemical modifications on water sorption and mechanical properties of Agave fibers. Composites: Part A, 39(2008) pp.29-45. [11] F.Zbidi, S.Sghaier, M.B.Nejma and M.Zidi, Influence of alkaline and enzymatic treatments on the properties of Doum Palm Fibers and Composite, Journal of Applied Sciences,2009 pp.366-371.
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