Study On The Thermal Stability And Processablity Of CPVC

Chlorinated polyvinyl chloride (CPVC) has a poor thermal stability, and tends to dehydrochlorinatc. Therefore, its products need to add thermal stabilizers to improve the thermal stability. The Lead (Pb) salt stabilizer is in the lead of the modern market of China. However, with the enhancing awareness of environment protection. Lead salt stabilizers have been limited gradually. Calcium (Ca) and zinc (Zn) thermal stabilizers is considered to be the substitutes for the Pb salt stabilizer because of the non-toxic and efficient features. Generally, the thermostabilization of domestic Ca/Zn thermal stabilizers are poor, and Ca/Zn thermal stabilizers used in hard CPVC products still have to rely on importing in China.In order to improve the thermal stability of the CPVC materials, the thermal degradation process of net CPVC was studied firstly in this paper. Calcium stearate and zinc stearate were used as the main thermal stabilizers. Dibasic lead phosphate^trisalty lead sulfate and organic tin were used as the auxiliary thermal stabilizers. Then the effects of these thermal stabilizers on thermal degradation processes and thermal stability of the blend systerm were discussed and researched. The results showed that with the addition of appropriate ratio of calcium stearate and zinc stearate, the thermal stability of CPVC was effectively improved. An excellent synergy between organic tin and calcium stearate were also observed, which could effectively delay the time of CPVC desorbed HC1. In addition, the thermal stability of CPVC was better with the addition of dibasic lead phosphate and trisalty lead sulfate than the addition of organic tin and calcium stearate. The effects of different thermal stable systems on mechanical properties of CPVC were also investigated. The mechanical properties were sightly decreased with the improving of thermal stability of the CPVC blend systerms.Finally, the best thermal stability systerm was obtained by adding the main and the auxiliary thermal stabilizers at the same time.