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Tensile and flexural properties of bamboo fiber / bamboo powder composites

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https://www.eduzhai.net International Journal of Composite M aterials 2013, 3(5): 130-135 DOI: 10.5923/j.cmaterials.20130305.03 Tensile and Flexural Properties of Bamboo Fiber / Bamboo Powder Composite Materials Shinji Ochi Department of M echanical Engineering, Niihama National College of Technology, Niihama city, 792-8580, Japan Abstract This paper describes the mechanical properties of the composite materials fabricated using bamboo fiber and bamboo powder. Bamboo powder can be hot press-molded much like plastic, and the use of these materials in place of plastic products would reduce the environmental impact of extensive plastic use. In the present study, the tensile and flexu ral strength of mo lded composites made fro m bamboo fiber and powder were examined. The results showed that the tensile and flexural strength of bamboo fiber / powder composites were increased with increasing fiber content. The other side, both strengths of composite were decreased with increasing molding temperature. The highest tensile and flexural strengths of the bamboo fiber reinforced bamboo powder composites specimens tested were recorded at 40.5M Pa and 107 MPa, respectively. Keywords Bamboo Fiber, Bamboo Po wder, Co mposite Materials, Tensile Strength, Flexu ral Strength 1. Introduction Recently, p lastic materials are indispensable in our lives as they are used e xtensively in many diverse fie lds inc luding, but not limited to, stationery goods, electronic products and sports goods. However, a great majority of these products are disposed into landfills after usage. Clearly, this contributes to a high environmental load. In order to reduce the environmental load generated from the disposal of used plastic products, significant attention has been placed on biodegradable plastics[1,2]. Th is plastic can be completely resolved into water and carbon dioxide by the action of the microorganis m, when d isposed of in the soil. Moreover, there are no emissions of toxic gases during incinerat ion. Recently, biodegradable plastics have been used in commercial p roducts such as ball-point pens, toothbrushes, garbage bags, fishing lines, tennis racket strings, wrapping paper and many others. Over the past few years a considerable nu mber of studies have been conducted on biodegradable composites containing plastics reinforced biodegradable natural fibers, such as bamboo[3-6], flax[7], jute[8], j p ineapple[9] and hemp[10] fibers. In the past, bamboo was used as part of daily life (e.g., bamboo shoots for food and stalks for building materials). Ho wever, recent ly, bamboo fo rests have fallen into ru in because of the appearance of plastic products and the import o f in e xp en s iv e b a mb o o s h o ot s . Th e p res en t st u dy investigated whether bamboo can be effectively used to replace plastic materials. In, the paper[11] reported last time, strength of the press-molded product made of bamboo powder was examined. The purpose of this research is to fabricate the bamboo material of high strength by reinfo rcing bamboo powder with bamboo fiber bundles. The bamboo fiber reinforced bamboo powder co mposites were molded fro m bamboo fiber bundle and powder, and the tensile strength and flexu ral strength of the resultant products were examined. These measured properties were subsequently compared to the mechanical properties of general plastic mater ia ls . 2. Experimental Procedures 2.1. Materials * Corresponding author: s_ochi@mec.niihama-nct.ac.jp (Shinji Ochi) Published online at https://www.eduzhai.net Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved 10mm Figure 1. Photograph of bamboo powder International Journal of Composite M aterials 2013, 3(5): 130-135 131 Tensile tests and three-point fle xura l tests were conducted using a testing machine (SIMADZU Model A G-250kNE), following JIS K7161 and JIS K7171, respectively. Tensile tests were performed at a strain rate of 1mm/ min and a gauge length of 50 mm. Flexural tests were performed at a crosshead speed of 1 mm/ min and a span length of 48 mm. Five specimens were prepared and analyzed. A 95% confidence interval was calculated by statistical analysis. 10mm Figure 2. Phtograph of bamboo fiber bundle In this research, bamboo powder (Miki Take za iten, Japan) of particle diameter o f 50〜200μm and bamboo fiber bundle (Ban, Japan) which have diameter of 100〜300μm and length of 10mm were used. Bamboo powder prepared mach ining a bamboo trunk. Steam explosion method was used to take out bamboo fibers. Steam explosion is the method when the water contains in bamboo is heated under high temperature and pressure, then bamboo is rapidly released to the atmosphere, so that the water evaporate into steam, result of parenchyma inside the bamboo shattered. Figure 1 and 2 show photographs of bamboo powder and fibres used in this work, respectively. 2.2. Mol ding Method of B amboo Fi ber / Powder Co mpos ites Table1 shows details of mo lding conditions in this study. The rate of fiber volu me is 0, 50 and 100%. Molding temperature is 160, 180 and 200℃. The specimens were fabricated using a hot press machine and a metallic mold. Specifically, to test specimens made under varying conditions, the bamboo fiber and powder was added to the metallic mo ld and held at three d ifferent temperatures pressed at 65 MPa. The tensile-test specimens were dumbbell-shaped with a width of 10 mm, a thickness of 3 mm, parallel portion length of 50 mm and a total length of 152 mm. The flexu ral-test specimens were made by the same method as the tensile-test specimen. Dimensions of the flexu ral-test specimens are a width of 15mm, thickness of 3mm and length of 100mm. Table 1. Molding conditions Molding temperature (℃) Powder (%) Fiber (%) 100 0 180 50 50 0 100 160 50 50 200 50 50 2.3. Method of Tensile and Flexural Test 3. Results and Discussions 3.1. Fabricati on of Press Mol ded Products Photographs of the surfaces of the different specimens observed using bright field microscopy are shown in Fig. 3 with specimens 100% of powder and 100% of fiber molded at 180℃ shown in Figs. 3 a )and b), respectively. A color of powder is yellow after mo ld. The color o f the fiber only specimen is darkness. Co lor of bamboo fiber changed by steam exp losion as shown in fig.2. Photographs of the fabricated press mo lded products using bamboo fiber and powder are shown in Fig. 3, with specimens mo lded at 160, 180 and 200℃ shown in Figs. 3 c), d) and e), respectively. As seen in these photographs, the color of the specimen mo lded at 160℃ is pale yellow; however, the color of specimen darkened with rising mo lding temperature. The surface of specimen exh ib its a strong brown at 200℃ . These results suggest that specimens browned on account of carbonization between 180 and 200℃. As shown in these figures, at 160℃, the fiber bundle and the parenchyma cell are clearly divided. On the other hand, it becomes increasingly difficu lt to distinguish the interface between the fiber bundle and the parenchyma cell with rising mold ing temperature. At 200℃, all aspects become almost a uniform bro wn, making the interface between the fiber bundle and the parenchyma cell indistinguishable. The relationship between the density of the specimens mo lded at 180℃ and fiber content is shown in fig.4. Fro m this figure, density of specimen is increased with increasing fiber content. It is thought that it is because density of a fiber is higher than it of powder mixed parenchyma and fiber. The densities of products molded at 0 and 100% of fibers are 1.39 and 1.42 g/cm3, respectively. The relat ionship between the density of the composites of 50% fibers and molding temperature is shown in Fig 5, and indicates that the density of specimens increased with rising mo lding temperature. Recall fro m Fig. 3, that the interface between fiber and parenchyma cell beco mes increasingly difficult to observe with rising mo lding temperature. It is considered that as a result of the increased bonding between fiber and parenchyma cell with rising mo lding temperature, the density of the molded products increased. The densities of products molded at 160 and 240℃ are 1.40 and 1.42 g/cm3, respectively. 132 Shinji Ochi: Tensile and Flexural Properties of Bamboo Fiber / Bamboo Powder Composite M aterials a) b) 5mm 5mm c) d) e) 5mm 5mm 5mm a) Powder 100% , 180℃ b) Fiber 100%, 180℃ c) Powder 50%-Fiber50%, 160℃, d) Powder 50%-Fiber 50%, 180℃, e) Powder50%-Fiber50%, 200℃ Fi gure 3. Phot ographs of fabricat ed bamboo fiber/powder composite mat erials Figure 4. Relationship between density and fiber content Figure 6. Relationship between tensile strength and molding temperature Figure 5. Relationship between density and molding temperature 3.2. Tensile Strength of B amboo Fi ber/Powder Co mpos ites Figure 7. Relationship between tensile strength and molding temperature International Journal of Composite M aterials 2013, 3(5): 130-135 133 a) b) 1mm 1mm d) c) e) 1mm 1mm 1mm a) Powder 100% , 180℃ b) Fiber100%, 180℃ c) Powder50%-Fiber50%, 160℃ d) Powder50%-Fiber50%, 180℃ , e) Powder50%-Fiber50%, 200℃ Figure 8. Photographs of fracture behavior after tensile test of bamboo fiber/powder composite materials Figure 6 shows the relationship between tensile strength and fiber content mo lded at 180°C. Fro m this figure, it can be seen that tensile strengths increase linearly with increasing fiber content. The tensile strengths were 36.8 MPa, in the samples with a fiber fract ion of 100%. Figure 7 shows the relationship between tensile strength and mo lding temperature. Fro m this figure, tensile strength decreased with increasing mold ing temperarure. Th is was expected as it was known fro m an earlier study that the strength of natural fiber decreases at temperatures above 180°C[12,13]. Therefore, it is thought that the strength of the molded specimens created fro m fiber bundles decreased at 200°C. Figure 8 shows fracture behavior after tensile testing. The figure shows that the fracture of fibers is observable by all specimens. However, in the case of the specimen mo lded at 160℃ (fig.8 c)), adds to the fracture of fibers, the pull out of fibers be able to observe at the part . In the case of specimens molded at 180 and 200℃, the fiber bundle and the parenchyma cell mixed homogeneously. However, fro m fig.7, tensile strength decreased with increasing mo lding temperature, the strength of the mo ld product decreased because strength of fiber in itself d ecreas ed [13]. 3.3. Flexural Strength of B amboo Fi ber/Powder Co mpos ites Figure 9 shows the relationship between fle xura l strength and fiber content. From this figure, it can be seen that flexu ral strengths increase linearly with increasing fiber content. The flexu ral strengths were 107.2 MPa, in the samples with a fiber fraction of 100%. Figure 10 shows the relationship between flu xu ral strength of 50% fibers and mo lding temperature. Fro m th is figure, strength decreased with increasing mo lding temperarure as same as tensile strength. The strength of the mo ld product decreased because strength of fiber in itself decreased as same as tensile strength. Figure 9. Relationship between flexural strength and molding t emp erat ure 3.4. Comparison wi th General Plastics Table 2 shows mechanical properties of general p lastic materials. The density of bamboo co mposite indicated same as polyacetal. The tensile strength of common plastic 134 Shinji Ochi: Tensile and Flexural Properties of Bamboo Fiber / Bamboo Powder Composite M aterials materials, polypropylene is 21〜37 MPa. Measurements of the press molded product of fiber 100% mo lded at 180℃ and composite of 50% fibers molded at 160℃ ind icated a tensile strength nearly identical to that of polyethylene. The flexu ral strengths of polyacetal are 100〜 110 MPa. The flexu ral strength of the press molded product using bamboo fiber of 100% molded at 180℃ and composites of 50% of fibers approached that of polyacetal. Based on these results, it is consider possible that bamboo fiber / powder co mposites could substitute effectively for conventional plastic products. 3. Tensile and flexu ral strength of composites decrease linearly with increasing mold ing temperature. In the case of mo lded at 160℃, the tensile and flexural strengths were 40.5 MPa and 104MPa, respectively. 4. The tensile strength was equivalent to polypropylene and the flexural strength was equivalent to general-purpose engineering plastics such as polyacetal. REFERENCES [1] Sina Ebnesajjad, Fluoroconsultants Group, Chadds Ford, Pennsylvania, U.S.A; formerly DuPont, Hundbook of Biopolymers and Biodegradable Plastics, William Andrew, 2012. [2] Haibin Zhao, Zhixiang Cui, Xiaofeng Wang, Lih-Sheng Turng, Xiangfang Peng, Processing and characterization of solid and microcellular poly(lacticacid)/polyhydroxybutyrate -valerate (PLA/PHBV) blends and PLA/PHBV/Clay nanocomposites, Composites Part B: Engineering, Vol.51, pp.79-91, 2013. Figure 10. Relationship between flexural strength and molding t emp erat ure Table 2. Mechanical properties of general prastic materials and bamboo fiber / bamboo powder composites[14] PE PP PC POM Powder100% 180℃ Fiber 100% 180℃ 50%-50% 160℃ 50%-50% 180℃ 50%-50% 200℃ density (g/cm3) 0.94 0.9 1.2 1.41 1.39 1.42 1.43 1.4 1.4 tensile strength (MPa) 8~23 21~37 56~67 62~70 12.9 36.8 40.5 29.2 23.1 flexural strength (MPa) 34~39 42~56 67~96 100~110 70.8 107.2 104 86.9 78.4 4. Conclusions In this research, press-molded specimens consisting of bamboo fiber /bamboo powder compostoes was fabricated and examined for their tensile and flexural strengths. Obtained results are summarized as follows: 1. The density of the press-mo lded product increased with rising mo lding temperature and fiber content. Density of composites indicated 1.39〜1.42 g/cm3. 2. Tensile and flexural strengths increase linearly with increasing fiber content. In the case of 100% of fibers, the tensile and flexu ral strengths were 36.8 MPa and 107.2MPa, res p ectiv ely . [3] H.P.S. Abdul Khalil, I.U.H. Bhat,M . Jawaid, A. Zaidon, D. Hermawan and Y.S. Hadi, Bamboo fibre reinforced biocomposites: A review, mechanicals and Design, vol.42, pp353-368, 2012. [4] K. M urali M ohan Rao, K. M ohana Rao, and A.V. Ratna Prasad, Fabrication and testing of natural fibre composites: Vakka, sis al, bamboo and banana, M aterials and Design, vol.31, pp.508-513, 2010. [5] A.V. Ratna Prasad and K. M ohana Rao, M echanical properties of natural fibre reinforced polyester composites: Jowar, sisal and bamboo, M aterials and Design, vol.32, pp.4658-4663, 2011. [6] S. Jain, R. Kumar and U.C. Jindal, M echanical behaviour of bamboo and bamboo composite. J M ater Sci, vol.27, pp. 4598–4604, 1992. [7] T. Stuart, Q. Liu, M . Hughes, R.D. M cCall, H.S.S. Sharma and A. Norton, Structural biocomposites from flax—Part I: Effect of bio-technical fibre modification on composite properties, Composites Part A: Applied Science and M anufacturing, 393-404, 2005. [8] D. Plackett, T. L. Andersen, W. B. Pedersen and L. Nielsen,, Biodegradable composites based on polylactide and jute fibres, Composites Science and Technology, Vol. 63, 1287-1296, 2003. [9] W. Liu, M . M isra, P. Askeland, L. Drzal and A. K. M ohanty, ‘Green’ composites from soy based plastic and pineapple leaf fiber: fabrication and properties evaluation, Polymer, Vol. 46, 2005. [10] A. K. Mohanty, A. Wibowo, M . M isra and L. T. Drzal, Effect of process engineering on the performance of natural fiber reinforced cellulose acetate biocomposites, Composites Part A: Applied Science and M anufacturing, Vol. 35, 363-37, 2004. [11] S. Ochi, Fabrication of Press-M olded Products Using Bamboo Powder, Journal of M aterials Science research, International Journal of Composite M aterials 2013, 3(5): 130-135 135 Vol.1/1, pp.156-166, 2012. [12] G. Testa, A. Sardella, E. Rossi, C. Bozzi and A. Seves, The kinetics of cellulose fiber degradation and correlation with some tensile properties, Acta Polymer, Vol.45, p.47-49, 1994. [13] S. Ochi, M echanical Properties of Heat-Treated Natural Fibers, Proc. High Performance Structures and Composites, pp .117-125,2002. [14] Tim A Osswald, Georg M enges, H. Georg L. M aterials Science of Polymers for Engineers, Hanser Grder Pubns, 2003.

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