Effects of fibre coating (size) on properties of glass fibre vinyl ester composites

Effects of fibre coating (size) on transverse cracking has been investigate d. Two glass fibre/vinyl ester model composites were studied, denoted CA an d NoCA and based on different size compositions. Various single fibre tests were not able to quantify the interfacial failure of CA as the interface n ever failed. The CA size consisted of a film former and a methacrylsilane-c oupling agent whereas the NoCA size did not contain any coupling agent. The study reveals limitations with single fibre composite tests for fibre/matr ix combinations with high interfacial toughness. Cross-ply laminates based on NoCA demonstrated significant inferior transverse cracking toughness as compared with CA laminates. Composites based on commercially sized glass fi bre were also investigated and they performed almost as poorly as the NoCA material, demonstrating large potential for improvement in commercial compo sites. Results further indicate that the remarkable transverse cracking tou ghness of the CA material stems partly from strong fibre/matrix adhesion bu t also from high ductility of the matrix region close to the fibre surface. (C) 1999 Elsevier Science Ltd. All rights reserved.