The effect of fibre/matrix interfacial interactions on the mechanical properties of unidirectional E-glass reinforced vinyl ester composites

This thesis first reviews, and then evaluates, the importance of fibre/matrix interfacial bonding in determining composite properties with particular reference to unidirectional E-glass reinforced vinyl ester systems. The potential of various non-destructive evaluation (NDE) techniques for determining the correlation between fibre treatment and bulk composite properties (such as interlaminar shear strength and tensile strength etc.) are described in detail. Acoustic Emission (AE) in particular is demonstrated to be useful in studying the process of damage during the mechanical tests. Some samples are also examined by optical and scanning electron microscopy, dynamic mechanical analysis, and by a new and novel technique known as Sound Image Analysis (SIA) which allows the total spectrum of crack sound output to be analysed. Overall it has been established that the NDE techniques used can distinguish between different levels of interfacial bond strength and that AE can follow the progressive changes in fracture mode that follow from fibre surface treatment variations.