STUDY OF FIBER SURFACE TREATMENTS FOR CONTROL OF INTERPHASE PROPERTIES IN COMPOSITES

Dynamic wetting measurements and micromechanical and macromechanical t esting have been used to characterize the fibre/matrix interaction. Un sized glass fibres, glass fibres sized with gamma-APS, poly(vinyl alco hol), gamma-APS/polyurethane or gamma-APS/epoxy, and untreated/unsized or treated/sized carbon fibres have been tested in combination with D GEBA-based epoxy resins of both amine and anhydride curing type. The e xperimental results of dynamic wetting show that the shape of the tens iogram depends on both fibre surface and resin chemistry. The slope of the force versus stage position plots represents the fibre/matrix int eraction as swelling or acid-base interaction and depends on stage spe ed and fibre roughness. Wilhelmy wetting tests can be used to study th e fibre/matrix interaction but conclusions about the resulting interph ase can be drawn only in conjunction with micromechanical and macromec hanical testing. Interfacial shear strength and transverse tensile str ength show evidence of the same ranking and reflect the expected inter phase behaviour. (C) 1997 Elsevier Science Limited.