Nanoscale characterisation of interphase in silane treated glass fibre composites

The properties of the interphase formed between a glass fibre and a polymer resin have been characterised based on novel techniques, including the nan oindentation and nanoscratch tests and the thermal capacity jump measuremen t. The variation of interphase thickness affected by differing silane coupl ing agents is specifically evaluated. The nanoindentation test gives an int erphase thickness of approximately 1 mum with Iarge variations between spec imens, and is not sensitive enough to identify the effect of different sila ne agents. The effective interphase thickness measured from the nanoscratch test varies between 0.8 and 1.5 mum depending on the type and concentratio n of silane agent. The higher is the silane agent concentration, the larger is the interphase thickness. These values are consistent with those measur ed based on the heat capacity changes in terms of general trend, although t he latter technique tends to present slightly higher values. The foregoing observations strongly support the usefulness of the techniques for interpha se characterisation. (C) 2001 Elsevier Science Ltd. All rights reserved.