THE EFFECTS OF HYBRIDIZATION ON THE MECHANICAL PERFORMANCE OF ARAMID POLYETHYLENE INTRAPLY FABRIC COMPOSITES/

Intraply hybrid composites have been fabricated by the open leaky-mold method in order to examine the effects of hybridization on the mechan ical performance of aramid/ polyethylene hybrid composite. The flexura l properties, interlaminar shear strength (ILSS), and impact propertie s of these composites have been studied as a function of aramid fibre content and loading direction. Two different stacking sequences ([0/0] (4) and [0/90](4)) were selected for this study, and composites of fou r different aramid fibre contents (100, 75, 50, and 0% by volume) have been studied. In addition, scanning electron microscopy (SEM) was use d to examine the fracture surfaces of the intraply hybrid composites. The flexural strength and modulus increased with the volume fraction o f aramid fibre, and negative deviations from the rule of mixture were observed in all intraply laminates. When the load was applied in the a ramid direction, the highest flexural strength was obtained. This is a ttributed to the fact that the flexural strength mainly depends on whi chever fibre is present in the longitudinal direction of the specimen. In contrast with the flexural property results, intraply hybrid compo sites exhibited lower ILSS values than polyethylene-fibre composites b ecause of the difference in the failure modes in the flexural and ILSS tests. In addition, intraply hybrid composites exhibited lower impact resistance than aramid fibre composites because the level of maximum load had a major effect on the impact absorption energy. (C) 1998 Else vier Science Ltd All rights reserved.