SEDL / STP / STP873-EB / STP34018S

Hygrothermal Degradation of Sheet Molding Compounds

Hosangadi, AB
Graduate student and professor of mechanical engineering, Washington University, St. Louis, MO

Hahn, HT
Graduate student and professor of mechanical engineering, Washington University, St. Louis, MO

Pages: 16    Published: Jan 1985

Download this paper for $25 PDF (368K)          View License Agreement
Abstract

Environmental variables such as moisture and temperature degrade fiber-reinforced polymer composites to various levels. This paper characterizes the hygrothermal degradation of a sheet molding compound (SMC) containing 65% by weight of E-glass fibers. Six different environments were chosen for the study: room temperature (RT)/65% relative humidity (RH), RT/98% RH, RT/water, 75°C/65% RH, 75°C/65% RH, 75°C/98% RH, and 75°C/water. The extent of degradation was evaluated using visual, microscopic, and chemical analysis techniques. From this study, distinct color changes and blistering on the specimen surfaces were evident. Degradation was manifested in the ultrasonic attenuation and in the reduction of short beam strength and stiffness.