NPL research focuses on developing measurement methods and predictive analysis for characterising interfacial properties of fibre-reinforced plastics and the role of the interface and interphase on thermal and mechanical performance of these materials.

Lateral force indentations for a moisture conditioned glass fibre-reinforced phenolic composite showing changes in reduced elastic modulus (Er) and lateral force signal (LFM) for the transition between fibre and matrix.

The aim is to provide more accurate methods and models for measuring and predicting interfacial and interphase properties to enable materials developers and users to tailor and optimise material performance. measurement techniques based on instrumented nanoindentation and atomic force microscopy have been employed to obtain high-resolution maps of the elastic modulus and topographic images for transitions between fibre and interphase, and interphase and matrix of composite systems.

The measurement techniques being developed are considered relevant to conventional continuous and discontinuous fibre-reinforced polymeric materials (including nanocomposites) and are expected to contribute to the improvement in multifunctionality of nanocomposites, and the use of new and improved environmentally resistant fibre systems in which the adhesion at the interface/interphase between fibre and matrix is critical to performance.