Metal oxide fillers, such as titanium dioxide (TiO2) are commonly used in building and construction applications and are added to increase the opacity and/or to improve the mechanics of a coating. However, their photoreactivity can contribute to degradation of surrounding polymer matrix, due to generation of electron-hole pairs that react further. Furthermore, outdoor weathering conditions, especially temperature and relative humidity, can also cause severe damage to polymeric coatings. The combination of these two factors is complex and difficult to separate. In this study, effects of temperature and humidity, separately, in addition to TiO2 photoreactivity, i.e. surface treatment and particle size, and its dispersion in an acrylic urethane matrix on the photodegradation of prepared films are examined. A suite of techniques, including laser scanning confocal microscopy (LSCM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), was used to follow the degradation of TiO2/polymer films as a function ultraviolet (UV) exposure, temperature, and humidity. LSCM was used to monitor morphological changes in both pigment dispersion and durability of the polymer matrix with degradation. ATR-FTIR was used to examine the chemical changes in the polymer with degradation. The results of these analyses are evaluated in context of pigment and polymer properties and pigment dispersion in the polymer system.
Proceedings Title: ACS Polymeric Materials: Science and Engineering Preprints
Conference Dates: March 21-25, 2010
Conference Location: San Francisco, CA
Conference Title: 239th ACS National Meeting & Exposition
Pub Type: Conferences
polymer, coating, degradation, photoreactivity, titanium dioxide