Study On The Application Of Composition With Mg, Al LDHs In Thermal Stability Of PVC

The lead salt stabilizers and organotin stabilizers are often used in PVC to control the degradation of PVC in processing. But lead salt stabilizers are poisonous and organotin stabilizers are expensive even if its higher security. It is necessary to seek a new kind of stabilizers that are secure, protecting environment and cheaper. Mg, Al LDHs is Mg_1-x²⁺Al_x³⁺ layered double hydride (LDH) of the hydrotalcites (LDHs), which can exhibit thermal stability during PVC aging. In this thesis, application of Mg, Al LDHs/Pb and Mg, Al LDHs /Sn composites in PVC pastes and rigid PVC were investigated. The thermal aging property and rheologic property were studied by using the aging instrument, spectrophotometer, TG, rhometer and universal mechanical testing instrument. The results show that there were both better synergism between Mg, Al LDHs and Pb and between Mg, Al LDHs and Sn. The thermal effect of LDHs/Pb composites and LDHs/Sn composites approach the effect of pure Pb or pure Sn. In PVC paste, LDHs/Sn=2.5/2.5 and LDHs/Pb=3/2(quality ratio) exhibit the best thermal stability. In rigid PVC without TiO₂, the thermal effect of LDHs/Sn=1.0/3.5 is better than the one of LDHs/Sn =0/4.5(quality ratio). In rigid with TiO₂,LDHs/Pb=1.5/3.5 exhibit...