SURFACE MODIFICATION OF A POLYPROPYLENE FILM BY LOW-PRESSURE DISCHARGE AND THE ADHESION OF A VACUUM-DEPOSITED LAYER OF ALUMINUM

Low-pressure discharge treatments were applied to the surface of polyp ropylene. ESCA analyses, wettability measurements and adhesion tests w ere carried out to characterize surface modifications as a function of treatment time and nature of gas (air or argon). Advancing and recedi ng contact angles were measured with an automatic dynamical tensiomete r. The liquids used were water (very polar liquid) and methylene iodid e (apolar liquid). The results show an increase in wettability by the surface treatment. This is due to the creation of high-energy polar si tes. ESCA analysis also shows that the modified surface layer is solub le in methanol and is made up of low-molecular-weight material. Adhesi on of polypropylene/aluminium is also increased by the low pressure di scharge treatment from the few first seconds of the treatment. This ad hesion increase is a function of the polar component of the polymer su rface energy.