The Influencing Factors And Structure Analysis Of The Thermal Stability Of In Situ Chlorinating Graft Copolymer

In situ chlorinating graft copolymerization (ISCGC) is a simplemethod for grafting polyolefine, of which the chlorination and graftcopolymerization of the polymer happed at the same time. In situchlorinating graft copolymer is prone to thermal degradation which is acommon defect for chlorinated polymer. Besides, there are abundant shortgrafting chains and branched points, much different with the structure ofchlorinated polyethylene. The thermal stability of polymer has a greatinfluence on the application and service life of materials, so studies on thethermal stability of this new kind of polymer are especially significant and necessary for exploring the materials. Chlorinatedpolyethylene-chlorinating graft-hydroxyl ethyl acrylate copolymer(CPE-cg-HEA) prepared via ISCGC was taken for example in this paper,and the thermal stability of in situ chlorinating graft copolymers, as wellas stabilizing mechanism and methods, were studied.In this paper, CPE-cg-HEA was studied as an example and thethermal stability was measured by TGA, Hakke torque rheometer andCongo Red Test. Compared with commercial grade CPE, the effect of thedifferences between chlorinating graft copolymers and chlorinatedproducts on the thermal stability of copolymers, as well as thermalmechanism, were explored. The thermal stability of industrialCPE-cg-HEA were also tested and analyzed.To explore the major influences on the thermal stability of in situchlorinating graft copolymers, the samples were removes HCl and thestructure was characterized by FT-IR, UV and1H-NMR to analyze andcheckout carbon-carbon double bond, vinylidene chlorines structure and adjacent chlorines structure. The contents of those structure units andchlorine distribution uniformity were analyzed and calculated by1H-NMR. The content of double bonds was tested by vinyl content test. Inaddition, the CPE-cg-HEA and commercial grade CPE samplesrespectively after heat treatment and longly placed were characterized andanalyzed to explore the influence of environments on the thermal stabilityof polymers. The industrial CPE-cg-HEA sample was characterized andtested to search for the effect of industrial conditions on the productstructure and thermal stability.At last, the thermal stability of CPE-cg-HEA samples, added withNaHCO3/DOP, calcium stearate or epoxy soybean oil/calcium carbonate,were tested by TGA and congo red test in order to explore the recipes ofan effective stabilizer system. The mixing methods were discussed tohighly improve the thermal stability of in situ chlorinating graftcopolymers.