Gas permeability measurement in polyethylene and its copolymer films

In this research, low density polyethylene (LDPE) and poly(ethylene-co-vinyl acetate) (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was film blowing and thermal-dry phase inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. To study film cross-section morphology in EVA, scanning electron microscopy (SEM) was applied. The results showed that the amount of permeability and solubility were decreased by increasing film thickness but diffusivity was increased. However, by increasing temperature, permeability, solubility, and diffusivity were increased. From the results for EVA, adding 28% of vinyl acetate groups to polyethylene chain increased permeability of O2 and CO2 through the film. Scanning electron microscopy (SEM) microphotograph for EVA film verified that the film cross-section structure was as dense as for polyethylene.