Effect of calcium silicate on foaming and anti‐shrinkage behavior of thermoplastic polyamide elastomers: Revelation of the open‐cell mechanism

Abstract

Thermoplastic polyamide elastomer (TPAE)/calcium silicate (CaSiO3) open‐cell foam with low shrinkage and high expansion ratio was prepared by using supercritical CO2 as a blowing agent. Adding CaSiO3 led to increased melt viscoelasticity and reduced crystallinity of TPAE. The primary mechanism of CaSiO3 promoting TPAE foam to form the open‐cell structure was discussed. The interaction between CaSiO3 and TPAE is fragile, making CaSiO3 easy to fall off the cell wall and form the open‐cell structure during foaming process. The increasing CaSiO3 content leads to increased cell density and thinned cell walls, thus increasing the tensile stress on cell wall. On the other hand, the agglomeration of CaSiO3 increases particle size, making it easier to fall off from the adhesion of TPAE matrix. The two aspects work together to improve the open‐cell content of TPAE foam up to 93.28%. The open‐cell structure is conducive to increasing the gas exchange rate and significantly decreasing foam shrinkage ratio. Finally, TPAE foam with a shrinkage ratio of only 2.68% and an expansion ratio of 18.77 times was obtained. In addition, open‐cell structure improves the adsorption performance of TPAE/CaSiO3 foam by 500%.