The effect of environmental ageing on the interphase in glass fibre - vinyl ester composites

The results of a study of environmental ageing on the apparent interfacial shear strength of glass fibre-vinyl ester microbond samples are presented. The scale related issues of estimating water absorption levels in microbond samples are reviewed and discussed and a solution based on Fickian diffusion is given. Interphase strength of microdroplets aged in water at 23 degrees C was relatively stable up to 6 days exposure after which strength degradation was fairly rapid. Immersion in water at 50 degrees C resulted in an immediate 20-30% irreversible loss of strength. Further exposure beyond 2 days led to total loss of integrity of the microbond samples. Electron microscope images of aged microdroplets appeared to show the development of a bi-phasic microstructure. The presence of two phases in small scale vinyl ester polymer samples was confirmed by DMA on thin films.

Automated summary

The study investigates the effects of environmental ageing on the interfacial shear strength of glass fiber-vinyl ester microbond samples. It reviews and discusses the scale-related issues of estimating water absorption levels in microbond samples and proposes a solution based on Fickian diffusion. The research finds that the interphase strength of microdroplets aged in water at different temperatures varies, with immediate loss observed in higher temperatures. Electron microscope images suggest the development of a bi-phasic microstructure in the aged microdroplets, which is confirmed by DMA analysis on thin films.