EFFECT OF UV AGING ON VINYL ESTER AND VINYL ESTER MATRIX COMPOSITES

摘要

The use of fiber-reinforced polymer (FRP) composite materials in civil infrastructure is being accomplished in an effort to improve the longevity and durability of bridge structures. This work specifically evaluates the affect of UV radiation, one of the typical environmental conditions encountered in bridge applications, on vinyl ester and vinyl ester matrix composites. Samples are presently being exposed to UV and high humidity in the outdoor environment of Miami, Florida in a long-term aging study. Initial results after one year of aging show extensive surface damage to the composite material but no significant impact on composite strength, modulus, and strain-to-failure. Neat vinyl ester resin and vinyl ester matrix composites have also been evaluated after laboratory exposure under a highly controlled and low temperature xenon arc bulb that replicates the UV radiation present in terrestrial sunlight. The laboratory apparatus accelerates aging at a level 4-5 times the outdoor environment based on an energy comparison. Scanning electron microscopy photographs show degradation of the matrix away from the fibers in the composite and the presence of surface cracking. The strength of these materials will be evaluated. Although vinyl ester degradation is observed in both outdoor and indoor aging, the FRP materials appear to retain their strength with the UV radiation only affecting the surface of the material. Continued exposure and evaluation will determine if the degradation spreads beneath the surface at longer aging times.