Effect of the blowing agent on the low-temperature mechanical properties of CO2- and HFC-245fa-blown glass-fiber-reinforced polyurethane foams

Glass-fiber-reinforced polyurethane foams, one of the most widely used insulation materials in liquefied-natural-gas cargo-containment systems, is generally blown by various blowing agents that exist in the gaseous state in closed cells. Hydrofluorocarbon-245fa, also known as HFC-245fa, is one of the most environmentally friendly blowing agents, but it has a high potential to contribute to global warming that is about 1000 times that of CO2. As a result, CO2 has received much attention as an ideal eco-friendly blowing agent. Therefore, a study was carried out to compare the low-temperature compression characteristics of CO2- and HFC-245fa-blown glass-fiber-reinforced polyurethane foams at various temperatures and strain rates. It was confirmed that the blowing agent affected the microscopic and mechanical characteristics of the glass-fiber-reinforced polyurethane foams. It also revealed for the first time that the compressive stress decreased as the strain rate increased when the test temperature was below the freezing point of the blowing agent, contrary to the tendency above the freezing point.