The effect of fiber treatment on the mechanical properties of unidirectional sisal-reinforced epoxy composites

The present paper investigates the effect of fiber treatment on the mechani cal properties of unidirectional sisal-reinforced epoxy composites. Treatme nts including alkalization. acetylation, cyanoethylation, the use of silane coupling agent. and heating were carried out to modify the fiber surface a nd its internal structure. As indicated by infrared spectroscopy. X-ray dif fraction and tensile tests, variations in composition. structure. dimension s. morphology and mechanical properties of the sisal fibers can be induced by means of different modification methods. When the treated fibers were in corporated into an epoxy matrix, mechanical characterization of the laminat es revealed the importance of two types of interface: one between fiber bun dles and the matrix and the other between the ultimate cells. In general, f iber treatments can significantly improve adhesion at the former interface and also lead to ingress of the matrix resin into the fibers, obstructing p ull-out of the cells. As a result, the dependence of laminate mechanical pr operties on treatment methods becomes complicated. On the basis of a detail ed analysis, the relationship between optimized fiber treatment and perform ance improvement of sisal composites was proposed. (C) 2001 Published by El sevier Science Ltd. All rights reserved.