Biorenewable blends of polyamide-4,10 and polyamide-6,10

Biobased polymers hold the promise of greatly improved sustainability metrics. In this study, semicrystalline polymer blends are formulated between two partially biorenewable polyamides. Polyamide 4,10 (PA410) is melt mixed with polyamide-6,10 (PA610). Physical properties of the blends are investigated using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), impact testing, and tensile testing. Morphological features are studied using small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS). The previously unreported equilibrium enthalpy of fusion for PA410 is found to be 269 J/g. Melting point depression from DSC is used to establish miscibility and calculate the polymer-polymer interaction parameter which is approximately independent of composition and equal to 20.25 kJ/mol. Crystallization induced phase separation is observed wherein crystallization drives phase separation. SAXS exhibits an increase in lamellar long spacing with increasing PA610 content. WAXS confirms the presence of only PA410 and PA610 crystals. The mechanical properties of the blends are shown to deviate from a simple law of mixtures. This miscible biorenewable polymer blend, exhibiting crystallization induced phase separation, and characterized by superior properties is of both scientific and potential commercial interest. (C) 2016 Wiley Periodicals, Inc.