ASSESSMENT OF THE EFFECTIVENESS OF SELECTED COATINGS FOR PROTECTION AGAINST UV RADIATION IN GLASS FIBER REINFORCED COMPOSITES (GFRP)

Abstract

The paper describes the effectiveness of selected protective coatings against ultraviolet radiation in glass fiber reinforced composites. Epoxy resin matrix GFRP composites with 1 mm thick coatings were produced. Four types of coatings were com-pared: pure epoxy resin, epoxy resin with the addition of a UV stabilizer from the benzophenone group, epoxy resin with an addition of graphite (screening function) and a commercial polyester gelcoat. The composites were irradiated for 1000 h with ultraviolet radiation from three separate radiation ranges: UVA, UVB, UVC. The changes in the surface appearance, flexural strength and chemical structure were described. The results shows that UV radiation caused changes in the surface condition for the reference samples (coating without additives), such as yellowing and matting. Also, a reduction in the flexural strength by over 10% and changes in the chemical structure, mainly caused by oxidation processes and the cracking of chemical bonds were observed. The most beneficial protection was found to be the UV stabilizer from the benzophenone group, the addition of which provides UV protection over the entire radiation range and protects the material against negative changes in the coat-ing’s chemical structure. Also, similar results were obtained for the samples with the graphite coating.