Transport and adhesion properties of an unlined and a liquid-crystalline polymer-lined vinyl ester thermoset exposed to severe environments

Abstract

The application of liquid-crystalline polymers (LCP) as lining materials for fiber-reinforced plastics was investigated. The lining consisted of one uniaxially and one biaxially oriented LCP and, for comparison, a fluorinated ethylene propylene copolymer. The lining was attached to a glass-fiber- reinforced vinyl ester thermoset. The laminates were examined with respect to their chemical resistance, transport/barrier properties, and lining/matrix adhesion behavior. The transport properties were determined by gravimetric desorption measurements and cup tests. It was shown that the LCP was suitable as a. lining in organic solvent and nonoxidizing acid environments. Diffusivities, equilibrium concentrations, and transmission rates of water, methanol, toluene, and trichloroethylene were obtained in the LCP, the fluorinated ethylene propylene copolymer, and also, in the case of the vinyl ester, of hydrochloric acid. In general, the diffusivity and transmission rate in the LCP were one to several orders of magnitude lower than those of the fluorinated ethylene propylene copolymer and the vinyl ester. The reinforcement in the glass-fiber-reinforced plastic led to an increase in the water and methanol diffusivities and transmission rates, which was probably attributable to liquid capillary diffusion. The lap-shear bonding strength between the LCP and the vinyl ester was poor, but it was improved almost sixfold by a combined abrasive and oxygen plasma treatment. © 2004 Wiley Periodicals, Inc.