Barrier Properties of EVOH at Low Temperatures and Various Humidities

摘要

Ethylene-Vinyl Alcohol Copolymer (EVOH) is an excellent barrier resin and is widely used in both food and non-food packaging applications~(1)). EVOH is hygroscopic, and thus the gas barrier properties of EVOH depend on humidity. The barrier properties of EVOH at low temperatures are important, as EVOH depend on humidity. The barrier properties of EVOH at low temperatures are important, as EVOH packaging films are often used at low temperatures such as in a refrigerator. We investigated the relationship between water absorption and oxygen transmission rate (OTR) of EVOH at low temperatures. As the results, it was found that the humidity where the OTR begins to increase closely related to the humidity dependence of glass transition temperature (Tg) of EVOH. The relationship between the OTR and the moisture content was clarified. Furthermore, calculating the solubility coefficient from the moisture, the solubility coefficient was represented as a function of the humidity, the temperature and ethylene content of EVOH. Therefore, using these relationship, we can estimate the OTR at any temperatures and any humdities.