Papers by Silas M . Mbeche
Due to global environmental pollution and high energy consumption, researchers have been stimulat... more Due to global environmental pollution and high energy consumption, researchers have been stimulated to seek for sustainable materials that can replace non-biodegradable and environmentally unfriendly materials in reinforced composites. Natural fibrereinforcements seem to be good alternatives since they are biodegradable, abundant, inexpensive and have excellent physical and insulation properties and high strength to weight ratio. Therefore, sisal and cattail fibres provide a better alternative. Kenya produces about 25,310 tons of sisal fibres annually. Furthermore, cattail plant (Typha angustifolia) is a common marginal weed in Kenyan wetlands. The aim of this work was to fabricate a fibre reinforced polyester hybrid composite from a blend of cattail and sisal fibres (alkali treated and untreated), to investigate the properties of these fibres and the effects of varying the ratios on the mechanical and thermal properties of the hybrid composites. The percentages of cattail and sisal fibres in the blend were varied from 0-100% (100/0,75/25,50/50,25/75,0/100) and moulded into hybrid composites using hand lay-up technique. Curing was carried out for 6 hours at room temperature under a pressure of 3.27kN/m 2 . The hybrid fibre weight fraction (wt.%) and cattail/sisal blend ratio were varied in order to determine their effects on the mechanical and thermal properties of the hybrid composites. Alkali treatment of the resultant composite was done by soaking some fibres in 4%w/v NaOH solution (sisal) and 5%w/v NaOH solution (cattail) for one hour at room temperature. Test specimens were prepared according to ASTM D638, ASTM D3410, ASTM D790, ISO 179 and ASTM C518 standards. Tenacity of treated sisal (146.26cN/tex) and cattail (35.35cN/tex) fibres was higher than that of untreated sisal (23.52cN/tex) and cattail (9.46cN/tex) fibres, while the linear density of treated sisal (10tex) and cattail (12.33tex) fibres were lower than 26.17tex and 35.17tex for the untreated fibres respectively. The flexural, tensile and compressive strengths of the hybrid composites increased as the proportion of sisal fibres was increased from 0-75% giving peak values of 45.97MPa, 32.39MPa and 25.43MPa respectively. Impact strength increased as the percentage of sisal fibres in the hybrid was increased from 0-100% to attain a maximum value of 34.40kJ/m 2 . Composites fabricated with alkali-treated fibres had better strengths (tensile-33.82MPa, flexural-45.68MPa, compressive-24.98MPa and impact-27.08kJ/m 2 ) than those fabricated with untreated fibres (28.89MPa, 36.65MPa, 21.05MPa and 23.19kJ/m 2 respectively). Cattail/polyester composites showed lower thermal conductivity (0.31W/mK) compared to 0.56W/mK for sisal/polyester composites. The mechanical and thermal properties recorded in this study indicate that these hybrid composites may be used for non-structural applications (as ceiling boards, walls, room partitioning, door panels and electronic and food packaging). However, further studies on their physical properties such as water absorption and flammability tests are required.
PeerJ Materials Science, 2020
Environmental and energy conservation pressure has led to a dramatic increase in the need for eco... more Environmental and energy conservation pressure has led to a dramatic increase in the need for economically feasible lightweight materials that can be better substitutes for non-biodegradable materials in reinforced composites. In this study, the mechanical and thermal properties of polyester resin composites hybridized with a blend of untreated and alkali treated sisal (Agave sisalana) and cattail (Typha angustifolia) fibers were evaluated. Composites were fabricated by a hand lay-up technique at an optimal hybrid fiber weight fraction of 20 wt% and a constant sisal/cattail fiber blend ratio of 75/25. Flexural, tensile, compressive and impact strengths and moduli, as well as thermal conductivity of the composites, were evaluated following ASTM and ISO test methods. Analytical results indicated that alkali pre-treatment of the fibers enhanced the mechanical properties of the hybrid polyester composites though only marginal differences were recorded in the thermal conductivity of the ...
Advances in Materials Science and Engineering, Mar 30, 2020
Due to environmental and energy conservation concerns, a thrust towards low-cost lightweight mate... more Due to environmental and energy conservation concerns, a thrust towards low-cost lightweight materials has resulted in renewed interest in the development of sustainable materials that can replace nonbiodegradable and environmentally unfriendly materials in reinforced composites. In this study, mechanical properties of a hybrid composite consisting of polyester resin reinforced with a blend of sisal and cattail fibres were evaluated. e composite was fabricated using a hand lay-up technique at varying hybrid fibre weight fractions (5 to 25 wt%) while maintaining a constant fibre blend ratio of 50/50. Composites were also prepared at a constant fibre weight fraction of 20% while varying the fibre blend ratio between 0 and 100%. Fabricated composites were then characterised in terms of flexural, tensile, compressive, and impact strengths following ASTM and ISO standards. Results showed that, at a constant fibre blend ratio of 50/50, there was increase in the mechanical properties as the fibre weight fraction increased from 5 to 20%. At a constant fibre weight fraction (20%), a positive improvement in flexural, tensile, and compressive properties was registered as the fibre blend ratio varied between 0 and 75% with optimal values at a sisal/cattail ratio of 75/25. e current study suggests that blending sisal and cattail fibres for production of polyester composites yields hybrid composites with enhanced mechanical properties.
Advances in Materials Science and Engineering, Mar 30, 2020
Due to environmental and energy conservation concerns, a thrust towards low-cost lightweight mate... more Due to environmental and energy conservation concerns, a thrust towards low-cost lightweight materials has resulted in renewed interest in the development of sustainable materials that can replace nonbiodegradable and environmentally unfriendly materials in reinforced composites. In this study, mechanical properties of a hybrid composite consisting of polyester resin reinforced with a blend of sisal and cattail fibres were evaluated. e composite was fabricated using a hand lay-up technique at varying hybrid fibre weight fractions (5 to 25 wt%) while maintaining a constant fibre blend ratio of 50/50. Composites were also prepared at a constant fibre weight fraction of 20% while varying the fibre blend ratio between 0 and 100%. Fabricated composites were then characterised in terms of flexural, tensile, compressive, and impact strengths following ASTM and ISO standards. Results showed that, at a constant fibre blend ratio of 50/50, there was increase in the mechanical properties as the fibre weight fraction increased from 5 to 20%. At a constant fibre weight fraction (20%), a positive improvement in flexural, tensile, and compressive properties was registered as the fibre blend ratio varied between 0 and 75% with optimal values at a sisal/cattail ratio of 75/25. e current study suggests that blending sisal and cattail fibres for production of polyester composites yields hybrid composites with enhanced mechanical properties.
PeerJ Material Science Chemistry , 2020
Environmental and energy conservation pressure has led to a dramatic increase in the need for eco... more Environmental and energy conservation pressure has led to a dramatic increase in the need for economically feasible lightweight materials that can be better substitutes for non-biodegradable materials in reinforced composites. In this study, the mechanical and thermal properties of polyester resin composites hybridized with a blend of untreated and alkali treated sisal (Agave sisalana) and cattail (Typha angustifolia) fibers were evaluated. Composites were fabricated by a hand lay-up technique at an optimal hybrid fiber weight fraction of 20 wt% and a constant sisal/cattail fiber blend ratio of 75/25. Flexural, tensile, compressive and impact strengths and moduli, as well as thermal conductivity of the composites, were evaluated following ASTM and ISO test methods. Analytical results indicated that alkali pre-treatment of the fibers enhanced the mechanical properties of the hybrid polyester composites though only marginal differences were recorded in the thermal conductivity of the composites fabricated with treated and untreated fiber blends. Morphological examination revealed that the major failure modes were fiber pull-outs and fiber fracture in composites fabricated with untreated and treated fiber blends, respectively. The composites produced could find non-structural applications as ceiling boards, electronic and food packaging materials but their properties such as wettability, crystallinity, flammability and other thermal properties need to be further investigated.
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Papers by Silas M . Mbeche