| Polyvinyl chloride (PVC) is one of the most widely used plastics because of its excellentflame resistance, corrosion resistance, weather resistance and simple processing conditions.However, PVC is extremely sensitive to temperature due to the characteristics of its ownstructure. The further application of PVC is restricted because of its poor thermal stability.Therefore, thermal stabilizer is necessary to the PVC processing. Presently, the traditionalthermal stabilizers mainly are lead salts and cadmium salts. But it is harmful to humanhealth and environment. Therefore, the development of new efficient and environmentallyfriendly thermal stabilizers has economic benefit and social significance. In order toovercome these shortcomings of traditional stabilizers, A novel organic antimony thermalstabilizer——antimony tri(isooctyl mercaptopropionate)(ATOM)was synthesized, and theeffect of ATOM on the thermal stability of PVC was investigated, and its action mechanismwas preliminary studied. The main research contents and results are listed as following:First, antimony tri(isooctyl mercaptopropionate)(ATOM) was synthesized fromantimony trioxide and isooctyl mercaptopropionate (IOMP) in organic solvent withconcentrated hydrochloric acid as catalyst, and its structure was proved by Fourier transforminfrared (FT-IR). The effects of molar ratio of antimony trioxide to IOMP, the reaction time,the choice and the amount of the solvent on the reaction were investigated. By the orthogonalexperiment with four factors and three levels, the optimal synthesis process was as follows:the molar ratio of antimony trioxide to IOMP was1:6.6, the best solvent was cyclohexane(accounts for about40%of the total weight of system), the reaction time was3h, the dense,yellow ATOM with the yield of88%was obtained.Second, the effect of ATOM on the thermal stability of PVC and its action mechanismwas studied. The effect of ATOM on the thermal stability of PVC was evaluated byBrabender torque rheometer. It was found that ATOM had a good thermal stabilization toPVC. Because it could absorb hydrogen chloride, replace the unstable chlorine atom of PVC,have addition reaction with double bond of PVC. Moreover, the thermal stability time of PVCcould reach25min with addition of3.5phr ATOM. The efficiency of ATOM was equal to thetraditional lead salt stabilizer. The thermal stability of PVC was enhanced with the increasing amnout of ATOM. Furthermore, the synergism of ATOM and Cast(or BaSt) wasstudied. The results showed that ATOM exhibited a good synergistic effect between them.When the amount of ATOM and Cast (or BaSt) were3.0phr and0.5phr respectively, thethermal stability of PVC was excellent. |
