Effect of Ultraviolet Absorber on Photo-Degradation of Epoxy Coating Studied by Slow Positron Beam

Abstract

The photo-degradation progress of epoxy coating and the effect of ultraviolet absorber under UV-B irradiation have been investigated in slow positron beam and by the Fourier transform infrared spectrometer. After 120 h of irradiation, the value of S parameter in sample bulk is reduced while compared with the virgin sample. The result is mostly due to post-cure process happening in this initial irradiation stage. As the irradiation time increases to 360 h, the S parameter decreases sharply. This is due to the growth of carbonyl group and the generation of free radical. After 528 h or longer time of irradiation, a very low S value was obtained near sample surface, indicating the formation of a dead surface layer. Positron results also reveal that the addition of ultraviolet absorber suppresses the development of the dead layer after long-term UV-B irradiation. Ultraviolet absorber has a suppressing effect on generation of polar groups towards sample bulk. The addition of ultraviolet absorber is a key factor that affects the photo-degradation of epoxy coating.

UV Sensor Based on Fiber Bragg Grating Covered with Graphene Oxide Embedded in Composite Materials

“…Due to their very good mechanical properties, epoxy resins are very often used as a matrix of composites or coatings in a variety of industrial applications: automotive, energy or construction, electromagnetic, electric and electromechanical, particularly in concrete constructions. Such nanocomposites should possess good adhesion with cement/concrete, as well as high fire resistance and good weatherability against UV, alkaline and saline environments [ 1 , 2 , 3 ].…”