EFFECT OF ALKALIZATION ON FLEXURAL PROPERTIES AND MOISTURE ABSORPTION OF KENAF FIBER REINFORCED COMPOSITES

摘要

The surface treatment method applied to natural fibers before manufacturing is responsible forreducing the moisture absorption capacity and enhancing the chemical and mechanical bondingpotential between the fibers and the matrix. Two common surface treatments used with bast(stem) fibers are alkalization, in which the chemical makeup and physical surface of the fibersare modified by soaking in a strong alkali solution, and treatment with silane coupling agents.Stitched kenaf fibers were treated with sodium hydroxide and/or a silane for differentconcentrations and durations, and then used to reinforce vinyl ester or polyurethane incompression-molded composite plates. The mechanical properties of the treated fibers werecompared by tensile tests of individual fibers and of the resulting composites by three-pointflexural tests. Moisture absorption was monitored for each variation of composite untilsaturation. Alkalization was shown to increase single fiber tensile strength by up to 30-50 % andcomposite flexural strength by as much as 25-35 % over untreated fibers. Treatment with silanesreduced the moisture absorption capacity of the composites by as much as 50 %. With the use ofproper surface treatments, natural composites can be competitive in structural applications.