Temperature and mold size effects on density gradients and mechanical properties in a polyurethane foam system.

摘要

Rigid polyurethane foams can be used as a thermal or vibration insulator and energy absorption material. They are often molded directly in place, where a smooth, thin skin forms between the mold and the cellular structure of the foam. Density gradients and the skin are shown to have an effect on the mechanical properties of the foam.; This work will investigate the effects of processing temperature and mold size on the average density, density gradient, compressive modulus, and compressive strength, for a molded free rise, water blown polyurethane foam system. Four processing temperatures are used during foam fabrication: 25°C, 40°C, 65°C, and 85°C. Three aluminum cylinder mold sizes are used with diameters of 29mm, 41mm, and 51mm. The properties are also compared to reference samples with a uniform density of 0.101 g/cc.; Results show that processing temperature and mold size have a significant effect on density, density gradients and some mechanical properties.