Evaluation of Thermal Endurance of Polyvinyl Chloride Foams and Closed-Celled Polyethylene Foams by Dynamic Compression Modulus

Effect of static strain on thermal deformation in foamed plastics was investigated in terms of the time dependence of compression dynamic modulus for polyvinyl chloride and closed-cell polyethylene based foams. In all foams, except for closed-cell polyethylene based foams subjected to 30 % static strain, the logarithm of time t at which the compression dynamic modulus decreased to 50 % of its initial value has been found to be a linear function of reciprocal absolute temperature T−1, and the correlation coefficient for the foams was more than 0.91. Because the stiffness of foam skeletons is influenced by inner pressure in closed-cells of polyvinyl chloride based foams, thermal endurance of the foams is improved by larger static strain.