Fabrication and determination of Mechanical properties of woven sisal fabric reinforced epoxy composites

Abstract

Engineering materials manufactured from synthetic fibres are responsible for global environmental pollution since they are non-biodegradable. Sisal natural fibers provide a better alternative as they are sustainable, biodegradable, inexpensive and available worldwide. Kenya produces over 28,000 metric tonnes of sisal fibres annually which is exported in raw form. The use of sisal fibres in composites fabrication will add value to the locally produced sisal. This will replace products currently manufactured from plastics and wood. This will create job opportunities, reduce environmental pollution and conserve the forests. The objectives of this research were to investigate the properties of woven sisal fabric reinforcement, fabricate woven sisal fabric reinforced epoxy composite, analyze the effect of fibre weight fraction (v wf ) and alkali treatment on the mechanical properties of the resultant composites and evaluate the mechanical (i.e. compression, tensile, impact and flexural) properties of woven sisal fabric reinforced epoxy composites. The method used in this research was experimental study whereby sisal fibre composites were fabricated by reinforcing epoxy resin with woven sisal fabric using hand lay-up technique. A mould measuring 310 x 310 x10 mm was fabricated in the School of Engineering Workshop and thoroughly cleansed. A mould release agent was applied on the mould surface before placing the weighed sisal fabric layers. The required quantity of the epoxy matrix was applied uniformly on the sisal fabric and the composites were allowed to cure at temperature of 23 0 C for 24-hours under a mass of 30kg (3.3kN/m 2 compressive pressure) that ensured uniform consolidation of the material. To investigate the effect of alkali treatment on the mechanical properties of the resultant composites, some fibres were soaked in 4% w/v NaOH solution for one hour followed by oven pre-drying at 80 0 C for another one hour before using them in composite fabrication (alkali treated samples) while other fibres were directly used without any surface modification (untreated/control samples). The fibre weight fraction for both treated and untreated composites samples was varied at 30, 40, 45, 50 and 60% using Central Composite Rotatable Design (CCRD) design of experiment Specimens for mechanical testing were prepared based on ASTM D638, ASTM D3410, ISO 179:1997 and ASTM D790 standards. Use of tables and bar charts was made in the analysis of data. The results showed that sisal woven reinforcement sustained higher tensile loads when tested along the warp direction than in the weft direction. The mechanical properties of alkali treated composites were found to be higher than untreated composites at the same fibre weight fraction. In both cases, the mechanical properties increased with increasing fibre weight fraction (V wf ). The tensile and compressive strengths increased from 22.63MPa to 30.91MPa and 15.32MPa to 23.91MPa respectively as fibre loading increased from 30%V wf to 50%V wf ; flexural strengths increased from 19.17MPa at 30%V wf to 27.16MPa at 60%V wf ; impact strength increased from 17.89KJ/m 2 at 30%V wf to 24.58KJ/m 2 at 45%V wf. The mechanical properties studies in this research show that the composites are strong enough to meet the essential requirements for non-structural applications such as ceiling boards and wall partitioning materials. Future research should study the physical properties such as water absorption and burning test of the sisal woven epoxy reinforced composites as well as cost analysis.