Effect Of Post-cure Conditions On Interfacial Properties Of Glass Fiber/vinylester Composites

Abstract

Microdroplet tests were carried out in order to investigate the effect of post-cure (PC) conditions on the interfacial properties of glass fiber/vinylester composites. Microdroplet test specimens were postcured at 80°C for a period varying from 4 h to 24 h. The load increased linearly up to the maximum pull-out load, when the load reached the critical load, beyond which the load reduced rapidly under all post-cure conditions. Shear debonding occurred in the fiber/matrix interface at the maximum pull-out load. The maximum load increased with a longer embedded length under all post-cure conditions. In addition, the maximum load was larger with a longer post-cure time. In the cases of PC for 48 h at room temperature plus 8 h and 16 h at 80°C, designated as PC8h and PC16h, respectively, debonding occurred at a short embedded length in contrast to other post-cure conditions. The post-cure conditions PC8h and PC16h improved the interfacial shear strength (IFSS) in comparison with that PC4h. The post-cure condition PC24h decreased the IFSS compared with PC16h. The sizes of the meniscus for both PC8h and PC16h were larger than those for both PC0h and PC4h. The surface of glass fiber was relatively smooth under all post-cure conditions. The residual thermal stress was increased due to post-cure. The mechanical anchoring contributed to the increase in the IFSS.