Development of EVA/POE/SEBS microcellular foam: Network structure, mechanics performance and midsole application

Thermoplastic elastomer foam is often used as a midsole, which is an important factor affecting sports efficiency. In this research, ethylene vinyl acetate copolymer/polyolefin elastomer/styrene ethylene butylene styrene (EVA/POE/SEBS) microcellular foam was prepared with supercritical nitrogen gas (SC-N 2 ). The influence of the formulation ratio on the matrix network structure was studied by vulcanization curve and rheometric expansion system rheometer. Then the foaming behavior and static/dynamic mechanical properties were studied, and midsole was prepared. The results showed that the increase of the relative content of SEBS reduced the viscosity of the matrix, but the loss factor increased, which further reduced the resistance to cell growth and increased the expansion ratio (density decreased from 0.19 to 0.13 g/cm 3 ). In addition, the increase of SEBS resulted in an increase in the static compressive strength and resilience (61%) of the foam. However, after 100 000 dynamic compression cycles, the increase of SEBS resulted in a decrease in the energy absorption capacity of the foam and an increase in the dynamic compression set (from 6.8 to 9.4%). This is significantly different from the traditional physical and mechanical performance test results, which are rarely reported and have significance for practical applications.