Structure and morphology of thermoplastic polyamide 6 elastomers with different soft segment content and their foaming behavior using supercriticalCO2

Abstract

AbstractThermoplastic polyamide elastomers (TPAEs) were synthesized using polyamide 6 (PA6) as hard segments and polyethylene glycol (PEG) as soft segments. The prepared TPAEs showed a superior mechanical property and thermal property, which the strength and elongation‐at‐break reached 35.50 ± 3.54 MPa and (316.05 ± 20.58)%, respectively, when the molecular weight of soft segment was 600. Furthermore, crystallization property and microphase separation of TPAEs were also investigated in detail, having a significant influence on the foaming behavior of the obtain elastomers. Owing to the restriction of crystalline hard segments, only a few cells formed in the amorphous soft segment regions at foaming temperature of 140°C, while it transformed to larger cells with a thin cell wall at foaming temperature of 160°C and above. When the molecular weight of soft segment increased from 300 to 1000, the average cell size of the foamed TPAEs at 160°C enlarged from 28.73 to 42.17 μm, while the cell density decreased from 5.26 × 108#/cm3to 4.25 × 108#/cm3, both expansion ratio and shrinkage ratio increased gradually.