Low-temperature and freeze-thaw durability of thick composites

Low temperature produces internal stresses in composites of polymeric materials. The polymeric matrix phase becomes stiffer, and may suffer from damage-inducing stresses resulting from thermal coefficient mismatch of fibers and resins. These influences have been studied by subjecting two types of FRP composites to flexural tests. A commercially procured fiber reinforced plastic (FRP) composite indeed produced cracks on prolonged thermal cycling between 50°C (122°F) and -60°C (-76°F) temperature. But a specially manufactured woven glass reinforced FRP did not produce any visual cracks for two and half times more thermal cycling in the same temperature range. It is suspected that the resin type and the curing process control the thermal cycle response and ultimate durability of such FRP composites in extreme temperature environments.