Surface properties of poly(lactic acid)/polyacrylate semi-interpenetrating networks - Effect of UVC radiation

Poly(lactic acid), PLA, was blended with multifunctional acrylate monomer (dipentaerythritol pentaacrylate) in various weight ratios (1:1 and 9:1). The reaction of photopolymerization of the acrylate monomer in poly(lactic acid) matrix was conducted to obtain semi-interpenetrating networks in the form of films dedicated for use in the packaging industry. Next, the PLA/polyacrylate films were exposed to UVC radiation in order to examine their photostability under the influence of high energy radiation, which can be used as sterilizing factor. In these studies, the following methods have been applied: contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). These methods made it possible to determine the influence of sample composition on the surface properties and photochemical resistance. It was found that PLA was the most susceptible to UVC-irradiation among the studied samples. In PLA/polyacrylate films UV light induced a slight increase in surface roughness and only negligible changes in surface polarity and chemical composition. The mechanism of photodegradation in the tested specimens was also discussed.