The effect of ethylene content on the interaction between ethylene-vinyl alcohol copolymers and water—II: Influence of water sorption on the mechanical properties of EVOH copolymers

This paper deals with the influence of water on the mechanical performance of ethylene-vinyl alcohol copolymers. A comparative study on the mechanical properties of six EVOH food packaging commercial grades with different ethylene contents has been carried out as a function of relative humidity by DMA and tensile testing. Two different cooling rates, i.e. fast and slow cooling, were used in order to study the effect of cooling speed on water/EVOH interactions. In agreement with the water transport results of a previous study, the current results indicate that there is a surprising anomalous antiplasticization regime for some mechanical properties below 30% RH, and that beyond this point further moisture sorption acts as the well reported effective plasticization agent for the mechanical properties.