Effect of Ultraviolet Absorber on Photo-Degradation of Epoxy Coating Studied by Slow Positron Beam
Zheng Wang a, Fuwei Liu a, Jingjing Li a, Chunqing He a, Xiangyang Peng b, Zhen Huang b and Pengfei Fanga
aDepartment of Physics and Hubei Nuclear-Solid Physics Key Laboratory, Wuhan University, Wuhan 430072, China
bElectric Power Research Institute of Guangdong Power Grid Co., Ltd, Guangzhou 510080, China
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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.

DOI: 10.12693/APhysPolA.132.1523
topics: epoxy coating, photo-degradation, ultraviolet absorber, slow positron beam, microstructure