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Effect of UV Radiation on Surface Mechanical Properties of NanoTiO2-Acrylic Urethane Composites



Pu-Jui Su, Bernard Haochih Liu, Stephanie S. Watson, Li Piin Sung


Nanoindentation was used to monitor the changes in surface mechanical property of nano-titanium dioxide (nanoTiO2)/acrylic urethane (AU) composites exposed to high intensity UV radiation at 55 ℃ and dry conditions. Five TiO2 nanoparticles of similar size but different crystal phases and surface treatments were selected in this study. Preliminary results indicate two competing behaviors (hardening versus softening) were found in surface modulus and hardness changes as UV exposure time increased. Relationship between photodegradation-induced surface mechanical behavior and the characteristics of nanoTiO2 (crystal phases and surface treatments) was examined. It appears that AU composites containing rutile nanoTiO2 regardless of surface treatment exhibit the typical hardening behavior. However, the AU composites containing anatase or anatase/rutile mix (high anatase ratio) nanoTiO2 show softening behavior. It implies that photoreactivity of nanoTiO2 plays a major role in the photodegradation-induced surface mechanical behavior. Other key physical parameters such as surface morphology and filler dispersion measured using laser scanning confocal microscope (LSCM), and bulk mechanical properties measured by tensile testing were obtained. The correlation between these physical quantities and the surface mechanical properties may provide a fundamental understanding of the photodegradation- induced surface mechanical behavior for different nanoTiO2/AU composites.
Journal of Coatings Technology


Composites, aser scanning confocal Microscopy, Nanoindentation, nanoparticles, surface morphology, Surface mechanical properties, UV degrdation


Su, P. , Liu, B. , Watson, S. and Sung, L. (2017), Effect of UV Radiation on Surface Mechanical Properties of NanoTiO2-Acrylic Urethane Composites, Journal of Coatings Technology, [online], (Accessed April 21, 2024)
Created October 16, 2017, Updated October 12, 2021