Foaming behavior of polyamide 1212 elastomers/polyurethane composites with improved melt strength and interfacial compatibility via chain extension

Abstract Long carbon chain thermoplastic polyamide elastomer (TPAE) with PA1212 as hard segment and polytetrahydrofuran as soft segment was synthesized successfully. Subsequently, thermoplastic polyurethane (TPU) incorporated to compensate for the high cost of TPAE and improved the foaming performance, in which a chain extender (ADR) was applied to enhance melt strength and interfacial compatibility simultaneously. The effect of ADR content on the mechanical, thermal, rheological, and foaming properties of TPAE/TPU composites were investigated in detail. It was found that the composite foams showed a more perfect cell structure, high cell density, and increased expansion ratio because of the enhanced melt strength and interfacial compatibility, when ADR was incorporated. With the increase of ADR content, the cell size and expansion ratio of the composite foams with TPU content of 30% showed a trend of first increasing and the following decreasing. The cell size reached a maximum value when the content of ADR was 2%, which was 25.81 μm. Consequently, the obtained TPAE/TPU composite foams showed an outstanding compressive modulus and resilient performance to broaden its application in footwear industry.