Investigation Andapplication Of The New Type Ca/Zn Thermal Stabilizer For Poly(Vinyl Chloride)

Poly(vinyl chloride)(PVC) has become the second largest demand material which first discovered from laboratory. This phenomenon is associated with outstanding performance of PVC. Compared with steel, metal and glass, PVC is lower cost, lower energy consumption, insulation and corrosion resistant. However, the polymerization technology used today exist structural defects which result in poor stability and easy to degradation. Therefore, thermal stabilizer is a necessary additive in fabrication of PVC. Nowadays, the thermal stabilizer is mainly lead salts and organotin. However, there are strong toxicity and high cost of these two stabilizers. Ca/Zn thermal stabilizer is considered as most safety one. At present, the main research target is to develop high performance Ca/Zn thermal stabilizer.In this paper, the new type thermal stabilizer, calcium glycerolate(CaGly) and zinc glycerolate(ZnGly) are synthesized. The structure of these two thermal stabilizers is clarified by some characterizations. Particles of zinc glycerolate are rod-like structure in micron level though transmission electron microscopy (TEM). The performances of CaGly, ZnGly which mixed with lathanum stearate (LaSt3) are discussed. ZnGly can delay the zinc burn effectively. The best performance is obtained at the ratio of 3 (in weight) between CaGly and ZnGly. Addition of LaSt3, Double-pentaerythritol (DPER),β-diketone can eliminated instable factors of PVC though synergism. Among these additives,β-diketone has highest performance. The excellent property is obtained at the ratio of 3 (in weight) between LaSt3 and ZnGly. In ternary system, the best performance is achieved at LaSt3/ZnGly/DPER=1.0/1.0/0.5 (phr). Moreover, the effect increases with the amount of additive thermal stabilizer.It is obtained that the stability order is PVC+LaSt3/ZnGly> PVC+CaGly/ZnGly>PVC>PVC+ZnGly though analysis of thermolysis dynamic with the method of Kissinger. CaGly and ZnGly can absorb the unstable chlorine atoms and HCl which comes from degradation. The process of thermal stabilization is conducted though these experiments.The optimized proportion of soft products is LaSt3, 0.7phr; ZnGly, 0.6 phr; ZnSt2, 0.1 phr; DPER, 0.7 phr;β-diketone, 0.2 phr; hydrotalcite, 0.2 phr. The static state thermal stabilization time can reach to 89.5 min. The color of PVC strip can hold 80 min under heat treatment at 200 oC, which is better than other products. The dynamic stabilization time can rise to 30 min when used in high transparency hard products. The obtained product has excellent lubrication property which can reduce the driving force and power.