Effects of environmental aging on the properties of pultruded GFRP

Pultruded glass-fiber-reinforced vinyl ester matrix composite coupons were subjected to environmental aging in order to study their durability since such composites are of interest for infrastructure applications. Specimens were tested as-received and after aging in water or salt solutions at room temperature (25 degrees C) or in water at 75 degrees C for various times. The flexural properties (strength and modulus) were determined for bending perpendicular to the 0 degrees orientations (0 degrees being the pull direction) for all aging conditions. In addition, flexural properties in the 90 degrees orientation and tensile properties in the 0 degrees orientation were also measured for the as-received specimens and the specimens exposed to selected aging conditions. Both strengths and moduli were generally found to decrease with environmental aging. Comparing the size of the fracture mirrors on the broken ends of the fibers in aged and un-aged samples suggested that environmental aging decreased the in situ fiber strength. In addition, examination of the failure surfaces and comparisons between the strength of the 90 degrees specimens suggested that degradation of the fiber/matrix interphase region also occurred during the aging process. (C) 1999 Elsevier Science Ltd. All rights reserved.