Salt-Fog Accelerated Testing of Glass Fiber Reinforced Polymer Composites

摘要

The objective of this project was to determine the durability under accelerated salt-fog exposure of six commercially available composites. These composites included glass- reinforced vinylesters, polyesters, phenolics, and an epoxy. Durability was measured mainly in terms of the loss of elastic modulus and flexural strength after exposure. In order to accelerate aging, the specimens were subjected to temperatures of 95F (35C), 120F (49C), and 160F (71C) for one, two and three months each while exposed to a salt-fog spray. A previous project had determined that among the common marine exposures, salt-fog was a major cause for degradation of composites used in the retrofit of the Navy's waterfront infrastructure. Flexural tests were performed, along with dynamic mechanic analyses and scanning electron microscopy. Once the aging effects were determined, a time-temperature superposition analysis was performed in order to extrapolate the results and estimate the degradation over longer time periods. Analysis predictions indicate losses of 35% or more in flexural strength over a 5-year period. To enable predictions beyond 5 years, additional and longer lasting testing would be necessary. Suggestions were made on how to introduce these findings in the design of composite material structures.