Comparison of the effect of thermal and hygrothermal sub-Tg aging on the durability and appearance of multilayered filament wound composite structure

The study conducts an experimental investigation to compare the effect of accelerated aging on a glass fiber/vinylester matrix filament wound composite. Two static aging conditions, thermal and hygrothermal, were chosen. Samples were aged at temperatures below the glass transition temperature (Tg) of vinylester for 224 days. Mechanical test - ILSS and flexure testing and physicochemical assessments - DMA, FTIR and colorimetry were conducted to gauge the aging effects on long-term durability and appearance. Results are presented as retained property values over aging durations and environments. Notably, coupons aged below 60 degrees C under both conditions exhibited residual curing, enhancing mechanical properties. Time-temperature coupling influenced behavior, with higher temperatures and longer durations leading to degradation. Hygrothermal aging at 80 degrees C prompted earlier degradation than thermal aging, highlighting moisture's impact. DMA revealed interfacial degradation for hygrothermally aged coupons, verified by fractography. Conversely, damping factor analysis indicated residual curing for thermally aged coupons. Results were confirmed through color change and FTIR, showcasing evolving chemical patterns with aging.