Durability of Reinforced Polymers under Adverse Environments: Interface Effects

摘要

Three types of experiments have been carried out to determine interface properties: single fibre pull out, transverse tests on unidirectional composites and peel tests on single fibres. The pull out tests were shown to give misleading results: interfaces which pull out suggested were as strong or stronger than the matrix, yielded transverse strengths which were low, and transverse fracture surfaces which had abundant bare fibres on them. Transverse tests showed that composites are weakened by water, but did not clearly reveal whether a weakened interface was a contributory factor. Peel tests did show that some interfaces are weakened by water. Interfaces studied included glass, carbon and Kevlar with epoxy and carbon-PEEK. This last was very resistant to water, being virtually unaffected after 8000 h at 90 deg C.