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Effect of Heterogeneity in Nano-TiO2 Filled Acrylic Urethane Coatings on Surface Degradation under Accelerated UV Exposure



Yongyan Pang, Stephanie S. Watson, Li Piin Sung


The objective of this study was to investigate how the heterogeneity due to nanoparticle dispersion of polymeric coatings affects surface morphological changes during ultraviolet (UV) exposure under different weathering conditions. Three types of nano-titanium dioxide (nano-TiO2) were chosen to mix into a solvent-borne acrylic urethane (AU) coating to generate different nanoparticle dispersion states. Two accelerated weathering conditions: wet (30 °C and 75 % relative humidity (RH)) and dry (30 °C and 0 % RH), were selected to investigate the effect of humidity on morphological changes in polymeric coatings. Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR FTIR) was used to monitor surface chemical degradation. Laser scanning confocal microscopy (LSCM) was used to characterize nanoparticle dispersion and monitor the surface morphological changes in the AU coatings during the UV exposure. Surface degradation patterns were different in these three coatings, and severe degradation was observed near large nanoparticle clusters. The degradation rate was estimated using chemical and physical changes as a function of UV exposure time. The surface degradation patterns were similar among the coatings containing the same type of nanoparticles in the wet and dry conditions, but the degradation rate was faster in wet conditions. Physical changes in surface roughness values present a better correlation to the surface degradation than chemical changes.
Polymer Degradation and Stability


Accelerated weathering, infrared spectroscopy, laser scanning confocal microscopy, nanocomposites, nanoparticle dispersion, photoreactivity, surface morphology, UV degradation


Pang, Y. , Watson, S. and Sung, L. (2014), Effect of Heterogeneity in Nano-TiO2 Filled Acrylic Urethane Coatings on Surface Degradation under Accelerated UV Exposure, Polymer Degradation and Stability (Accessed April 19, 2024)
Created October 29, 2014, Updated October 12, 2021