EFFECTS OF FIBER COATINGS ON MECHANICAL-PROPERTIES OF UNIDIRECTIONAL GLASS-REINFORCED COMPOSITES

Glass fibers were coated with an elastomeric material based on an epox y-amine formulation. The process involved the continuous impregnation of fibers with a solution of the monomers, followed by solvent evapora tion and cure along heated tubes. Temperature profiles were selected t o attain a high conversion level at the exit while avoiding monomer lo sses. Unidirectional composites, including the coated fibers in a comm ercial epoxy-anhydride matrix, were produced by using the combined tec hniques of filament winding, vacuum bag and autoclave processing. A co mparison of the mechanical properties of composites prepared from coat ed or uncoated fibers, at the same porosity level, revealed that the i nterlaminar shear strength remained constant while the transverse tens ile strength was slightly decreased by coating the fibers. However, th e transverse impact strength was significantly improved. Scanning elec tron microscope fractographs provided an explanation of the observed e ffects. (C) 1997 Elsevier Science Limited.