Effect of solubility and miscibility on the adhesion behavior of polymer-coated carbon fibers with vinyl ester resins

Interfacial shear strength (IFSS) of carbon fibers with vinyl ester resin w as investigated as a function of the structure of the polymer coating on ca rbon fibers via microdroplet tests. For coating carbon fibers, high-perform ance polymers such as poly(arylene ether phosphine oxide) (PEPO), Udel(R) P -1700, and Ultem(R) 1000, water-soluble poly(hydroxy ether ethanol amine) ( PHEA), water-dispersed carboxy-modified poly(hydroxy ether) (C-PHE), and wa ter-insoluble poly(hydroxy ether) (PHE) were utilized. Adhesion of polymers to carbon fibers was also evaluated and the failure surface of the fibers was analyzed by SEM to understand the adhesion mechanism. Diffusion between polymers and vinyl ester resins was investigated and the solubility parame ters of the polymers were calculated, with the results being correlated to the IFSS. A highly enhanced IFSS was obtained with PEPO coating, while marg inally improved IFSS resulted from PHE, Udel(R), and C-PHE coatings. Howeve r, PHEA and Ultem(R) coatings showed no improvement. Such results were attr ibuted to the extent of solubility and/or miscibility of polymer coatings i n vinyl ester resin, with better solubility and miscibility leading to a hi gher IFSS. (C) 2000 John Wiley & Sons, Inc.