Oxygen barrier, free volume, and blending properties of fully bio‐based polyamide 11/poly(vinyl alcohol) blends

Fully bio-based polyamide 11 (PA11) was melt-blended with poly(vinyl alcohol) (PVA) with varying degrees of polymerization (DP) to prepare PA11(x)PVA(y)(z). The PA11(x)PVA(y)(z) films demonstrated the lowest oxygen transmission rates (OTR) and free volume characteristics, when PVA contents of each PA11(x)PVA(y)(z) series reached a corresponding critical concentration. The minimum OTR and free volume characteristics obtained for the optimal PA11(x)PVA(y)(z) films reduced significantly with decreasing PVA DPs. The OTR of the optimal PA11(x)PVA(y)(z) blown film was 1.07 cm(3) m(-2) day(-1) atm(-1), which is near to that of the ethylene-vinyl alcohol copolymer high-barrier polymer. The results of dynamical, mechanical, and other experimental characterizations demonstrated that PA11 and PVA are compatible to some extent when PVA concentrations are less-than or equal to the respective critical values. The enhanced oxygen permeation resistance and free volume characteristics for optimal PA11(x)PVA(y)(z) films are at least partly ascribed to the improved hydrogen-bonded molecular interactions between PA11 C(sic)O groups and PVA OH groups. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48562.