Mechanical properties of epoxy- and dicyclopentadiene-based carbon-fiber-reinforced plastics at low temperature

Abstract

In this study, the material properties of carbon-fiber-reinforced polymers (CFRPs) at room and low temperatures (at 20°C and − 196°C) were examined, where the mechanical properties and failure characteristics of two types of CFRP with thermoset resins (epoxy (E) and dicyclopentadiene (D)) were used. For the low-temperature tests, the mechanical properties were investigated using an originally designed testing system, where the mechanical properties were examined in a container, made of styrofoam, filled with liquid nitrogen (LN). LN was supplied automatically as the amount of LN decreased, where the level of LN was monitored using a capacitance sensor. The bending and fatigue strengths of both CFRPs were enhanced at -196°C compared with those at 20°C due to high internal strain at low temperature. Furthermore, the high creep strength was detected for D-CFRP at -196°C compared to that for E-CFRP. This could be attributed to the high ductility of D-CFRP. In particular, the bending stress of E-CFRP dropped suddenly during the static bending loading, which could be affected by the delamination between epoxy and carbon fiber, although the D-CFRP sample was highly strained during the loading process without severe delamination. This could be attributed to the high wettability between dicyclopentadiene and carbon. Details of the wettability and the above material properties of both CFRPs were analyzed in this paper.