Abstract
The effects of matrix resin, curing condition and absorbed moisture on the interlaminar shear strength of carbon-fiber unidirectionally reinforced epoxy composites were investigated in comparison with those on the flexural properties of epoxy resins used as the matrix. Four composites were made from aromatic amine-cured and acid anhydride cured epoxy resins and high-strength and high-modulus type carbon-fibers. Interlaminar shear tests by a short beam method for the composites and flexural tests for the epoxy resins were conducted at various constant temperatures.
The results obtained are summrized as follows
1) The shear strength of the composites reinforced with high-strength type carbon-fiber was nearly independent of the matrix, while that with high-modulus type one was not. However both of them showed remarkable dependence upon temperatures as well as the flexural properties of the epoxy resins did.
2) Curing condition changed the flexural properties of the epoxy resins, but did not have any significant effect on the shear strenght of the composites except at high temperatures, where the interlaminar shear was not observed.
3) Moisture had a considerable effect on the flexural properties of the epoxy resins and the shear strength of the composites. There was the combined effect of moisture and curing condition on the glass transition temperature of the epoxy resins, but the decreases in the flexural properties and the shear strength by moisture absorption were little affected by curing condition except at high temperatures.
