Low temperature response of pultruded composites at saturation

The longitudinal and transverse properties of typical pultruded composites at saturation, saturation with freeze-thaw cycling and saturation with continuous freezing were investigated. Dry reference was also tested at low temperature for comparison. Degradation was observed to occur more significantly after the moisture uptake than the subsequent low temperature cycling. Stiffness loss appeared to be less than 10% in longitudinal direction but could reach 17% in transverse direction. Reduction in strength due to the environmental exposure was in a range of 10–27% and happened in both directions. The two-year water absorption tests at room temperature resulted in much less strength loss at saturation than the hot water accelerated tests. Pultruded composites proved to be more resistant to low temperature damage than moisture attack. A moisture resistant resin would substantially improve the performance of composites for cold regions engineering.