The multiple functions of titanium dioxide (TiO 2 ) in exterior PVC durability are reviewed. TiO 2 absorbs UV light to protect the polymer from direct UV degradation, and provides light scattering for visible light for opacity and to mask the discoloration of PVC. In addition, TiO 2 photocatalytically degrades the PVC surface which is detrimental to gloss retention and causes colour fade. The chalking effect of TiO 2 to PVC surface degradation was further analysed and the acid solubility test was introduced to differentiate the chalking grades and durable grades. A two year outdoor weathering study of rigid PVC at representative exposure sites included exposures in the USA, France and Belgium. The gloss loss and colour change due to weathering and UV exposure was discussed with the influence of different exposure climates, stabiliser types, TiO 2 loading and chalking effects.
A facile strategy for anatase titanium dioxide (TiO 2) nanoparticle preparation was proposed via a non-aqueous precipitation method. With the aid of glacial acetic acid, tetrabutyl titanate underwent non-hydrolytic reaction in solvent ethanol. Glacial acetic acid increased polarity of TiO and CO bonds of tetrabutyl titanate, and promoted non-hydrolytic de-etherization poly condensation reaction to form TiOTi bond in the solvent. After refluxing at 80℃ for 24 h, the TiOTi bond was rearranged to form anatase TiO 2 nanoparticles with the particle size of 5 nm-20 nm and specific surface area of 169.4 m 2 /g, which exhibited good dispersion and excellent photocatalytic activity. The degradation rate against methyl orange under ultraviolet radiation for 2 h reached 99.81%, showing promising prospect in wastewater treatment process.
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