Anti-shrinkage, high-elastic, and strong thermoplastic polyester elastomer foams fabricated by microcellular foaming with CO2 & N2 as blowing agents

Thermoplastic polyester elastomer (TPEE) is a high-performance polymer with high tear strength and excellent abrasion resistance, and microcellular TPEE foams exhibit low density and special mechanical properties. Nevertheless, shrinkage behavior of the TPEE foam is still a critical challenge which greatly limits its industrial application, and further, the shrinkage mechanism is rarely figured out. Herein, a novel strategy of implementing mixed CO 2 & N 2 as blowing agents in microcellular foaming was developed to stabilize cell structure. Thanks to the modest permeability of mixed blowing agents, TPEE foams with high stable expansion ratio of higher than 17-fold and recovery ratio of up to 77 % were fabricated, and it found that the ratio of mixed blowing agents could modulate the shrinkage behavior of TPEE foams. Moreover, the correlation between the mechanical properties and TPEE foams with different shrinkage behaviors was investigated. For TPEE foams with similar stable expansion ratios, decreasing the shrinkage helped to increase the maximum compressive stress by 100 % and to reduce the energy loss coefficient by 43 %. Overall, the developed microcellular foaming prepared with the mixed CO 2 & N 2 as blowing agents shows great promise in fabricating advanced elastomer foams with high expansion ratio, stable cell morphology and outstanding mechanical properties. • Tunable thermoplastic polyester elastomer (TPEE) foams were prepared with CO 2 & N 2 . • N 2 effectively decreased shrinkage of TPEE foams as co-blowing agents. • Microcellular TPEE foam with a stable expansion ratio of 17 was achieved. • Foam with low shrinkage had high compressive stress and low energy loss coefficient.