Ultraviolet Light Resistance on the Properties of Polyurethane Coating with the Addition of Chlorinated Rubber

Abstract

Resistance to ultraviolet light is an essential factor that coating materials must possess, especially for outdoor applications. In this study, the effect of ultraviolet light exposure on the properties of polyurethane coating with the addition of chlorinated rubber was systematically examined. The ultraviolet light exposure was performed using an ultraviolet weathering tester for 500 hours. The samples were investigated through mechanical testing, complemented by scanning electron microscope and Fourier transform infrared spectroscopy. The increase in the tensile strength and elongation at break of the polyurethane coating with the addition of chlorinated rubber was observed and compared to the pristine sample. In the beginning of the ultraviolet exposure, the tensile strength increased 486% and 114% for pristine polyurethane and polyurethane/chlorinated rubber until of 80 hours ultraviolet exposure, indicating repolymerization during the ultraviolet exposure. It was confirmed by the Fourier transform infrared spectra which showed an increase in peak intensity at wave number of 1712 cm־ˡ which indicated C=O bond in the polyurethane. The surface morphology showed micro-cracking caused by ultraviolet exposure. Finally, it was concluded that the addition of chlorinated rubber improved the resistance to ultraviolet light.