Supercritical foaming of novel poly(ether-b-amide) elastomer and compression property characterization

Lightweight foam made of poly(ether-b-amide) (PEBA) elastomer has been widely used in sport shoes due to its superior rebounding and supporting properties. Novel PEBA with polyamide 1012 as hard segments and poly(tetramethylene oxide) (PTMO) as soft segments was foamed by supercritical CO2. The influence of foaming process parameters, that is saturation temperature, pressure on the morphology of cellular structure was systematically studied by scanning electron microscopy (SEM) and wide-angle x-ray diffraction (WAXD). By controlling the viscoelastic behavior of PEBA at certain temperatures and pressures, foams with low density and energy loss coefficient can be fabricated. The cell density of 4.5 x 10(9) cells/cm(3) and expansion ratio of 16.0 of the foams can be obtained respectively. Cyclic compression performance of foams was systematically studied. For the foams with the highest expansion ratio, the energy loss coefficient of 11.9% in the first cycle and 3.5% after equilibrium were observed, which were less than those of former reported PEBA foams. The relationship between the Young's modulus and expansion ratio is in line with the Gibson-Ashby relationship.