Abstract
The weathering performance of various grades of untreated (or uncoated) and treated (or coated) rutile pigments in commercial polyethylene in the absence and presence of primary and secondary antioxidants is examined. Using carbonyl index as a monitor of the rate of photo-oxidation, untreated rutile sensitizes the photo-oxidation of polyethylene, whereas the treated grades act as photostabilisers. The photosensitizing effect of untreated rutile is markedly inhibited by a synergistic combination of a hindered phenol (Topanol CA) and a sulphur containing antioxidant (DLTDP). Further, the order of weathering stability of the treated rutile pigments in the absence of any antioxidant in the polymer is altered significantly when an antioxidant system is present. The imporance of pigment/antioxidant interactions is discussed. The photo-oxidation of polyethylene containing the treated rutile pigments is also significantly improved by the presence of a primary antioxidant or a primary/secondary antioxidant system compared with a secondary antioxidant alone. These results indicate that peroxides play only a minor role in the photo-oxidation of TiO2 (rutile) pigmented polyethylene.
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Allen, N.S., Bullen, D.J. & McKellar, J.F. Photo-oxidation of commercial polyethylene containing titanium dioxide (rutile)/ antioxidant systems. J Mater Sci 12, 1320–1324 (1977). https://doi.org/10.1007/BF00540845
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DOI: https://doi.org/10.1007/BF00540845