Morphology, mechanical, and water transport properties of melt blended EVOH/PVOH films. Issue 13 (16th May 2019)

• Record Type: Journal Article
• Authors: Blanchard, Anthony; Gouanvé, Fabrice; Espuche, Eliane
• Is Part Of: Journal of polymer science. Volume 57:Issue 13(2019)
• Page Start: 838
• Page End: 850
• Publication Date: 2019-05-16
• Subjects: blends -- hydrophilic polymers -- mechanical properties -- morphology -- polymer blends -- structure‐property relations; water permeability -- water sorption; 547
• DOI: 10.1002/polb.24840
• Languages: English
• ISSNs: 0887-6266

Abstract

ABSTRACT: Herein, we report for the first time the successful preparation of ethylene–vinyl alcohol (EVOH)/poly(vinyl alcohol) (PVOH) blends by a melt blending process for PVOH volume content ranging from 0 to 30%. Thermal stability up to 270 °C was maintained for all blends. The blends morphology consisted in spherical low size PVOH domains homogeneously dispersed in the EVOH matrix with good interfacial properties. An increase of the mean size of the PVOH domains (from 0.3 to 1.2 μm) and of the size distribution was evidenced as the PVOH content increased. The contribution of each phase to the water sorption and diffusion was clearly demonstrated. The impact of water uptake was investigated on the chains mobility by using Gordon–Taylor law and on the mechanical properties of the blends with respect to the reference polymers. It was pointed out that the reinforcing effect of PVOH phase decreased as the water activity increased. However, a significant elongation at break was maintained, underlining the major role played by the EVOH continuous phase at high water activity. Finally, it was shown that adding PVOH to EVOH up to 15 vol % allowed strengthening the material at low water activity and keeping interesting elongation at break and barrier properties at high water activity. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 838–850 Abstract : Ethylene–vinyl alcohol/poly(vinyl alcohol) (PVOH) films were successfully prepared by a melt blending process for the first time. The blends exhibited a two‐phase structure with good interfacial adhesion. A detailed analysis of the water sorption and diffusion properties was carried out, and water permeability at high relative humidity was discussed as a function of the PVOH content. The chain mobility and mechanical properties were analyzed as a function of hydration rate. Optimized blend compositions for functional properties were determined.