Titanium dioxide salts, stabilization

Certain metal salts effectively reduce the photoactivity of titanium dioxide pigments. Combination of these salts with an appropriate antioxidant and/or ultraviolet stabilizer provided highly efficient stabilization of polypropylene. The deactivation/ stabilization performance of the metal salts is adequately explained on the basis of their decomposition of hydrogen peroxide at the pigment surface and by annihilation of positive holes in the pigment crystal lattice. 

Polyvinylidene fluoride (PVDF) is considerably less thermally stable than PTFE but much more stable than polyvinyl fluoride (PVF) or polychlorotrifluoroethylene (PCTFE). Certain inorganic compounds (silica, titanium dioxide, and antimony oxide) can catalyze its decomposition at temperatures above 375°C (707°F) [10], ETFE degradation is autocatalytic and similar to that of PVDF and is accompanied by the evolution of hydrogen fluoride (HF). Iron and transition metal salts can accelerate the degradation of ETFE by dehydrofluorination and oligomer formation [10], Copper salts have been found to stabilize the polymer [11], ETFE decomposes rapidly at temperatures above 380°C (716°F) [11],... 

Titanium has a tendency to accumulate in tissues. The concentrations can be very high, as indicated in Table 9.5. Titanium was not excreted in the urine of hamsters injected with metal salts (Merritt et al, 1992). Small concentrations were found in the serum, red blood cells and organs. Only 5.5% of the injected titanium was found in the kidneys, liver, lung and spleen tissues. The authors suggest that titanium accumulates at the injection site due to the high stability of the titanium dioxide that is formed at physiological conditions. In the same study nearly all the injected vanadium was recovered in the urine. This behaviour is similar to that of nickel and cobalt, and is related to the formation of highly soluble compounds. 

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