Alkali Treatment of Kenaf Fiber Mat and its Influence on the Performance of Unsaturated Polyester/Kenaf Fiber Mat Composites

Non-woven kenaf fiber mats were prepared from untreated and alkali treated fibers by using a carding machine followed by needle punching. The alkali treatment was carried out by immersing the fiber mats in 6% NaOH solution for 0, 1, 2, 3, 4, and 5 h at room temperature. The untreated and alkali treated fiber mats were impregnated with unsaturated polyester resin via a resin transfer molding technique to form composites. Maximum improvements of flexural strength and flexural modulus of the composites were observed when the fiber mat was alkali treated for 3 h. The improved of both properties can be attributed to better fiber-matrix adhesion between the alkali treated kenaf fiber and the unsaturated polyester matrix most probably via mechanical interlocking. Water absorption tests were conducted by immersing the composite samples in distilled water at room temperature. The water absorption patterns of all the composites were found to follow Fickian behavior. The tendency of the composites to absorb water decreased when the alkali treated fiber mats were used.