| INFLUENCE OF NANO-TIO2 ON THE PERFORMANCE OF POLY (VINYL CHLORIDE CO-ISOBUTYL VINYL ETHER) AND ITS ANTI-CORROSION COATINGXIANG Bin (Marine chemistry)Directed by: Professor HOU BaorongWith the rapid development of national economy and the advance of ocean and west exploitation strategy, a large number of steel structures rushed. The demand for long life, environment friendly and high weather resistance coating is much higher and more urgent, but it can't meet the demand now, especially the weather resistance. Because of the few of study on the clean and environment friendly poly (vinyl chloride co-isobutyl vinyl ether) coating and the strong UV shield of nano-TiO2 which might improve the performance of anti-corrosion, this paper had investigated on the optimal dispersion conditions through settlement and TEM, and the influence and mechanism of some typical kinds of commercial nano-TiO2 on the performance of poly (vinyl chloride co-isobutyl vinyl ether) and its anti-corrosion top coatings in mechanics, weather resistance and anti-corrosion through AC impedance, UV accelerated aging, IR and XPS. An optimal prescription of coating was gotten. It is the first and exploring study on the application of nano-TiO2 in poly (vinyl chloride co-isobutyl vinyl ether) coating.After the choice of some nano-TiO2 and dispersants, it was found that the obvious dispersion difference of nano-TiO2 with different types and surface treatments, i.e. A made by CVD was easy to disperse, but DJ3 by sol-gel was difficult; the usage of dispersant for nano-TiO2 was 10-15 times of ordinary TiO2.The hardness of the coating was enhanced 1-2 grades with addition of rutile nano-TiO2(B), while not for addition of anatase nano-TiO2(A), which indicated that the greater influence of particle size and shape of nano-TiO2 on the mechanics performance of coating.It showed that the 2 types of nano-TiO2 had different influence on the aging of resin under UV radiation, i.e. the A obviously accelerated the aging, while B could distinctively shield UV and lighten the aging of resin. The mechanism of resin UV aging as follow was put forward: free radicals produced from the surface of nano-TiO2 attack the hydrogen of the methylene, then double bond is formed after the dehydrocholrination, and then the chain is broken after the double bond was oxidized by ozone. The skin effect of chlorine and oxygen in the coating was found the first time by the author, i.e. chlorine and oxygen were enriched in the surface layer, while titanium in the inner layer. As for the influence of the skin effect on the coating need to be further studied. The UV aging speed of indoor was slower than the outdoor exposure, so the author brought forth the accelerated effect of moisture on the UV aging of the coating.It was also found that the decrease of immersion resistance and impedance of the commercial anti-corrosion of poly (vinyl chloride co-isobutyl vinyl ether) coating with increase of directly adding of nano-TiO2, which was elucidated with the theory of critical pigment volume concentration (CPVC). At last, the optimal coating prescription was gotten as follows: 0.5-1.0g nano-TiO2 B, 25.6g resin, 33.4g xylene, 1.4g chlorinated paraffin, 1.5g 15% slurry of organic bentonite, 0.8g green chrome, 7.7g grey mica ferric oxide and 0.6g non-float aluminum.
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