Interfacial charge in polyethylene/ethylene vinylacetate laminates

Space charge formation in polyethylene (PE)/ethylene vinylacetate copolymer (EVA) laminates has been investigated using a pulsed electroacoustic method. The PE shows heterocharge while the EVA shows a broad distribution of positive charge over the sample. The positive charge in EVA decreases with the increase of vinylacetate (VA) content in EVA. Interfacial charge is found in all laminates and remains unchanged by heat treatment at 100/spl deg/C to 1 h and by coating chemicals such as silicone oil and trimethylolpropane trimethacrylate at the interfaces, This interfacial charge distorts the electric field distribution in the direction of increasing the electric field in the PE layers. The charge distribution in PE/EVA blends has been measured and is explained via the results obtained with the laminates.