The Preparation And Performance Research Of N-Containing Organic Compound Heat Stabilizers

Polyvinyl chloride (PVC) is a heat-sensitive resin.It is easy to degrade and remove HC1 molecule under high temperature and high shear.So that the products would be discolored and decline in performance.Heat stabilizers are indispensable additive in PVC processing,which can improve the degradation temperature of PVC and make it possible of PVC molding. As the enhancement of people’s environmental awareness and enforcement of related environmental regulations and conventions.research and application of PVC heat stabilizers is toward the direction of non-toxic and environmentally protection.This thesis synthesised two kinds of organic heat stabilizers.which were N-phenylmaleimide(N-PMI) and N-nitrobenzene maleimide(N-NPMI).Maleic anhydride as the main raw material reacted with aniline and nitrobenzene amine respectively. The effects of the synthetic route and conditions on the yield of the two kinds of products had been researched and determined.They were two-step method,xylene as the solvent,silicon acid as the catalyst and phosphoric acid as the dehydrating agent. The structures of two products were analyzed and characterized by nuclear magnetic resonance spectroscopy and Fourier transform infrared.N-PMI or N-NPMI was respectively compounded with stearate(CaSt、ZnSt)、 hydrotalcite(LDHs),etc.The influences of the ratio of components in the composite heat stabilizers system on PVC static and dynamic thermal stable properties、processability、heat aging property and the impact of the release rate of HCl were systematically studied with Congo red tester、HAAKE、thermal aging oven and conductivity tester.The results showed that the thermal stability of PVC could be significantly improved by adding LDHs into the system of N-PMI or N-NPMI.Through comprehensive comparison,the best ratio of N-PMI/LDHs in binary complex system was 9/1,which was the same as the best ratio in multi-complex system.And that,when the content of Ca(OH)2 was 0.2 phr.,the thermal stability of the whole complex system was the best.The optimal ratio of N-NPMI/LDHs in multi-compound thermal stable system was 5/5.The multiple composite thermal stable system of N-PMI/LDHs or N-NPMI/LDHs were respectively compared with Ca/Zn about their thermal stability.The comparative study showed that the first two systems were much better than the system of Ca/Zn on static and dynamic thermal stability.While,there were no big changes on heat resistance、flexural strength and impact strength of materials.Therefore the multiple composite thermal stable system of N-PMI/LDHs or N-NPMI/LDHs could replace the traditional Ca/Zn composite thermal stable system.