Development And Application Of The Novel Calcium-zinc Thermal Stabilizer For Polyvinyl Chloride

Polyvinyl chloride (PVC) is one of the most popular synthetic resins, and due to a large number of excellent performances, its products are widely used in all areas of production and living. However, the molecular chain of PVC containes a number of chlorine atoms, which lead to an uneven distribution of electron density between chlorine atoms and molecular chain, and ultimately, the reaction of thermal dehydrochlorination will appear in PVC above 110℃because of this serious flaw. The processing temperature of PVC is higher than 140℃, so it is necessary to add in the thermal stabilizer to ensure the successful completion of processing of PVC.At present, the conventional thermal stabilizers, such as lead-salt and organic tin, have the toxicity at a certain extent, and lead to environment pollution. With the improvement of people's awareness for environment protection, the thermal stabilizers with non-toxic and no heavy metal contamination cause more and more attentions from many researchers in now days.In this paper, bis-(γ-stearoylglyceryl-α,β-) boronium hydride was designed by the means of dmol3 program with density functional theory-based, choosing the boron atom with an empty orbit as the central atom, and boric acid as a matrix for modification. At first, the geometricconfiguration, mulliken charge, fukui index and frontier molecular orbit were simulated and optimized, and it is found that bis-(γ-stearoylglyceryl-α,β-) boronium hydride has a potential thermal stability. Bis-(γ-stearoylglyceryl-α,β-) boronium hydride was synthesized using boric acid, glycerine, and stearic acid as the raw materials. Finally, the novel calcium-zinc thermal stabilizer was prepared by melting compound bis-(γ-stearoylglyceryl-α,β-) boronium hydride and calcium-zinc oxide.The application performance of products for PVC was tested by methods of thermal oven and thermogravimety. A possible stabilization mechanism of the novel Ca-Zn thermal stabilizer was proposed. The results demonstrated that the novel calcium-zinc thermal stabilizer have a higher thermal stability and thermal oxidative stability for PVC when compared with the calcium-zinc stearate thermal stabilizer. Further more, choosing phosphate ester as the co-stabilizer can bring about a higher synergistic effect. The stabilization mechanism is mainly manifested as the elimination for the unstable structure of PVC and the absorption of HCl degraded from PVC.