Mechanism of Action of Titanium Dioxide Pigment in the Photodegredation of Poly(Vinyl Chloride) and Other Polymers

Abstract

338 1. 337 3. POLYOLEFIN -TiO 2 SYSTEMS 368 3·1 Polyethylene 368 3·2 Polypropylene 369 4. OTHER POLYMER -TiO 2 SYSTEMS 369 4·1 Polycarbonate 369 4·2 Acrylates and paints 370 4·3 Polystyrene 371 5. CONCLUSIONS 371 6. ACKNOWLEDGEMENTS 372 7. REFERENCES 373 ABSTRACTThe extensive use of titanium dioxide as a pigment and optical agent in polymers, particularly poly(vinyl chloride), polyethylene and alkyd resins, has prompted many investigations of the various deleterious effects (loss of gloss and mechanical properties, chalking, pinking) of long-term exposure to sunlight of the pigmented polymers. This short review summarises the fundamental semiconductor processes undergone by TiO 2 on UV irradiation and the consequent chemical action of the reactive intermediates so generated. It also describes the strategies developed to counteract photodegradation induced by TiO 2 , in particular its encapsulation in a coating by near-UV transparent metal oxides, such as Al 2 O 3 and SiO 2 , with wide band gaps. The effects of doping TiO 2 with transition metal ions are also noted. Scheme 3. Summary of the photodegradation of PVC. Scheme 4. Mechanism of photodegradation of PVC [19].

Study on the Photodegradation Stability of Poly(butylene Succinate-co-butylene Adipate)/TiO2 Nanocomposites

“…In the studies mentioned [10][11][12][13][14][15][16][17][18][19], the TiO 2 nanoadditives have attracted a high degree of attention, mainly because they are not only UV-screening agents but also performance-enhancing additives. Furthermore, as TiO 2 is more refractive than that of most light-colored inorganic additives, such as SiO 2 , Al 2 O 3 , ZnO, and others, the ability of shielding UV radiation is stronger than that of other additives [20]. e purpose of this paper was to improve the photodegradation stability and prolong the service life of PBSA by adding nano-TiO 2 additives based on their UVscreening characteristics.…”

Effects of stratospheric ozone depletion and climate change on materials damage

“…In general opacifiers such as coated titania filler to enhance the light stability of polymer such as PVC by shielding the polymer from UV radiation. 48 Nanoscale fillers now becoming commercially available have much smaller particle sizes and therefore considerably larger surface area available for interaction with radiation. Nano-sized TiO 2 , for instance, has an average particle size of about 15 nm and an average surface area of ∼100 m 2 g −1 as opposed to conventional TiO 2 of particle size of size ∼300 nm and surface area of 8 m 2 g −1 .…”

The role of titanium dioxide on the behaviour and fate of plastics in the aquatic environment

“…Because of its high light scattering efficiency, inertness, thermal stability, dispersability and cost-effectiveness, titanium dioxide (TiO 2 ) is the most widely employed pigment in plastics (Kemp and McIntyre, 2001). Two polymorphic forms of TiO 2 are used: rutile (refractive index = 2.61) and anatase (refractive index = 2.56).…”