Effect of aluminum oxide coating on structural, barrier and electret properties of polyethylene terephthalate films

Polyethylene terephthalate film 12 μm thick with vacuum-deposited AlO_x coating was studied. Optical and atomic force microscopy was used to investigate surface topology. Film haze, optical density, surface tension, oxygen and vapor transmission rates were measured to estimate barrier performances of the film. To study effect of the coating on electret properties of the film surface potential, electric field strength and efficient surface charge density and thermally stimulated surface potential relaxation were measured. Optimal charging conditions for coated and uncoated polyethylene terephthalate films were found. Interaction of the film with different model mediums simulating foodstuff was studied. Coated electret film can be used as active packaging material with high barrier properties.