Polymeric foams for cryogenic temperature application: Temperature range for non-recovery and brittle-fracture of microstructure

In the present study, low-temperature material characteristics of polyurethane foam, glass fiber-reinforced polyurethane foam, and polyisocyanurate foam were investigated. These foams are key candidate materials for use in membrane-type liquefied natural gas insulation systems. Liquefied natural gas insulation systems should be able to withstand severe environmental conditions, such as fluid induced impact loading under cryogenic temperatures. For the robust design of insulation system, both failure characteristics and deformation recovery capacity of the materials must be evaluated. Therefore, the failure characteristics and the deformation recovery ratio of the foams were investigated at various temperatures and strain rate levels. The present study revealed that the fracture behavior and the recovery ratio were significantly affected by decreases in temperature. As a newly obtained insight, it has been found that the recovery ratio for all tested materials significantly decreased at −163°C. This finding is the opposite of the behavior that typically occurs at low temperatures. In particular, polyurethane foam specimen after experiment at the temperature of −163°C was easily broken into pieces even under the application of small loads. In addition, it has been revealed that polyisocyanurate foam showed superior mechanical characteristics at cryogenic temperatures owing to the ring structure of isocyanurate.