Property improvements of EVOH by enhancing the hydrogen bonding

Ethylene-vinyl alcohol (EVOH) with excellent barrier properties is insufficient in mechanical properties, which limits its application. For the purpose of enhancing mechanical properties of EVOH, blend of anhydrous magnesium chloride (MgCl₂) with EVOH was prepared by melt blending. Enhanced hydrogen bonding can be achieved through interaction between the Cl of MgCl₂ and -OH in EVOH, and the stronger hydrogen bonding between MgCl₂ and EVOH was confirmed by using Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy. The chemical, thermal and mechanical properties were evaluated. The thermal analysis of blends demonstrated that the melting temperature (T_m), the crystallisation temperature (T_c) and the crystallinity were effectively decreased with adding MgCl₂, on the contrary, the glass transition (T_g) was significantly increased from 42.8 to 77.5°C. The mechanical test results revealed that MgCl₂ can significantly improve the storage modulus and the viscosity of EVOH, also the tensile strength was raised by nearly 30%.