engleski

Modification of Physico-Chemical Properties of Acryl- Coated Polypropylene Foils for Food Packaging by Reactive Particles from Oxygen Plasma

This investigation was focused on the influence of long- living neutral reactive oxygen species on the physico- chemical properties of acryl-coated polypropylene foils for food packaging. Reactive species were formed by passing a molecular oxygen through a microwave discharge and leaked to a processing chamber of a volume of 30 L, which was pumped by a rotary pump. The density of neutral O-atoms in the chamber was tuned by adjustment of both the effective pumping speed and the oxygen leak rate. The O-atom density was measured with a catalytic probe and was between 3×1018 and 5×1019 m-3. Commercial foils of biaxially oriented polypropylene (BOPP) coated with acrylic/ poly(vinylidene chloride) (AcPVDC) were mounted in the chamber and treated at the room temperature by O atoms at various conditions with the fluence between 1×1021 and 3×1024 m 2. The evolution of the surface wettability versus the fluence was determined by water contact angle (WCA) measurements, the formation of functional groups by X-ray photoelectron spectroscopy (XPS) whereas the morphology by atomic force microscopy (AFM). The WCA dropped from the initial 75° to approximately 40° after the fluence of few 1022 m-2 and remained unchanged thereafter, except for fluences above 1024 m-2 where the WCA dropped to approximately 30°. XPS and AFM results allowed for drawing correlations between the wettability, surface composition and morphology.

plasma surface modification ; polymer polypropylene ; neutral oxygen atom density ; initial surface functionalization ; food packaging ; wettability

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