Adhesion of glass/epoxy composites influenced by thermal and cryogenic environments

Little information regarding the effects of prior thermal and cryogenic conditionings on hydrothermal and mechanical behavior, for varied volume fractions of constituent phases in polymer matrix fiber composites, has been published to date. The present experimental investigation uses flexural test to assess the effects of thermal and cryogenic treatments, and concurrently followed hydrothermal aging on quality of adhesion of multilayered laminates for 55, 60, and 65 wt % of E-glass fiber-reinforced epoxy composites. The specimens were conditioned at 80°C and ?80°C temperatures for different time durations, and thereafter they were immediately immersed in boiling water for an hour. Water absorption rates were evaluated for those conditioned specimens in such environment. Absorption study in hydrothermal aging showed a remarkable variation for the two cases of prior conditionings. The shear strength values were compared with the test value of as-cured samples. Degradation of mechanical property was found to be less prevalent during hydrothermal aging, with a prior conditioning at 80°C temperature compared to ?80°C treated glass/epoxy composites. Improved shear strength for almost all conditions of thermal conditioning in the initial stages has highlighted better adhesion influenced by postcuring phenomena during thermal or cryogenic conditioning. It was also observed from water absorption data that high temperature conditioning contributed more strengthening effect and better adhesion at the interfaces. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1943–1949, 2006