Synthesis, Characterization And Properties Of Modified Chlorinated Polyvinyl Chloride With Higher Strenghth And Softening Point

The main purpose of this paper is to prepare a modified CPVC with special structure and high performance by grafting MAH onto CPVC chain. The high chlorines contents (66%wt, as structural material) and anhydride modified CPVC was obtained by ISCGC of PVC and MAH, which had not been reported in the past. The most prominent feature of the graft copolymer is that the product not only has higher strength but also a certain degree of toughness compare with common CPVC due to the increased polarity of polymer chain by MAH grafting. At the same time, material's Vicat softening temperature was increased evidently.In this work, the graft copolymerization of maleic anhydride (MAH) grafted onto Chlorinated polyvinyl chloride (CPVC) with high chlorine content (66%wt) via in-situ chlorinating graft copolymerization (ISCGC) was prepared with improved mechanical strength,softening point and thermal stability of the material. The structure of the graft product (CPVC-cg-MAH) was characterized by FT-IR, 1H-NMR, GPC and UV. CPVC-cg-MAH contains less vinylidene chloride (CCl₂) units and double bond than corresponding CPVC. Meanwhile, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of CPVC-cg-MAH are increased, but distribution of molecular weight (Mw/Mn) is decreased. Then, the tensile strength and notched impact strength of CPVC-cg-MAH increased by 14.5% and 34.6% respectively. Furthermore, the results of DMA, DSC, TG and Vicat softening point showed that the loss peak of CPVC-cg-MAH was higher evidently than CPVC and moved to high temperature, initial weight loss temperature and maximum weight loss rate temperature of CPVC-cg-MAH increased by 7.2°C and 11.1°C respectively and the Vicat softening temperature of CPVC-cg-MAH increased by 15°C and up to 130°C.At the same time, the effects of chlorine content, monomer contents and reaction temperature on grafted degree, mechanical properties and softening point were explored detailedly.In addition, the performance of CPVC and PVC blends was improved by CPVC-cg-MAH blends instead of CPVC in this paper. Results show that, compared with CPVC/PVC blends, the mechanical properties and Vicat softening point of CPVC-cg-MAH/PVC was increased.