Preparation Of Polyvinyl Chloride Grafted With Maleate And Properties Of Its Blend

Polyvinyl chloride(PVC) has many advantages such as light mass, chemical corrosion resistance, electrical insulation, flame retardant, high strength and good processability. But because of it containing a large number of polar groups which make the molecular inter-atomic forces strong and with poor processibility, brittle, and lack of elasticity and flexibility. Usually the processability, elasticity and pliability, and low temperature brittleness of PVC are improved by the addition of plasticizer. However, because most plasticizers are small organic molecules and its addition level is up to 30 wt %-50 wt %, after a long time of implantation, plasticizer is easy to migrate even to precipite,which cause the degradation of properties of PVC products, meanwhile, it maybe cause environmental pollution. Based on this, this paper grafted different maleic acid ester group on poly(vinyl chloride) by chemical method in order to investigate the influence of these groups. This work can lay the foundation for preparation of poly(vinyl chloride) composites with good properties in industrial production.In this paper preparation process of PVC-g-MAH by microwave method is discussed, based on this, PVC-g-DBM and PVC-g-DOM are prepared for the first time. Optimum conditions for processing three kinds of grafted products, and thermal stability and molecular weight distribution of three grafted products were studied. The results show that: the optimum conditions for the synthesis of PVCg-MAH are: the dosage of MAH is 20 wt% of DPVC, dosage of APS is 3 wt%, heating power is 630 W, reaction time is 30 min, the graft degree is 5.02 %; The optimum conditions for synthesis of PVC-g-DBM, dosage of catalyst is 3 wt% of MAH, the molar ratio of maleic anhydride and n-butyl alcohol is 1:2.15, dosage of DIC is 3 wt% of MAH, reaction time is 4h, the enterification rate is 91.07 %; The optimum conditions for the synthesis of PVC-g-DBM are ascertained through RSM, the dosage of catalyst is 4 wt% of MAH, the molar ratio of maleic anhydride and n-butyl alcohol is 1:2.15, dosage of DIC is 3 wt% of MAH, reaction time is 4 h, the enterification rate is 91.02 %. The thermal stability of grafted poly(vinyl chloride)(GPVC) is improved obviously, there is no significant difference in the molecular weight and distribution of PVC and GPVC, grafting did not cause the degradation of PVC.Blending the GPVC and PVC to prepared different composites, to test the processability and mechanical properties, electrical properties, low temperature resistance, resistance transference and appearance characteristics of four composites system, the results showed that comparing to PVC composites system, the balance torque of PVC-g-MAH/PVC, PVC-g-DBM/PVC and PVC-gDOM/PVC decreased 2.2 N·m, 2.5 N·m and 3.1 N·m, respectively, processability of the PVC composites system is improved. The tensile strength and elastic modulus of PVC-g-MAH/PVC is high, but its elongation at break is rather low, the trend of the other two composites are going in the other direction. Compared with PVC composite system, the breakdown strength of the three composites are increased, but the resistivity is decreased, performance and resistance to low temperature achieved- 25 ?; The weight loss rate of PVC is 11.12 %, but that of the three kinds of composites is 4.64 %, 4.01 % and 3.50 %, respectively, the migration of the small organic molecules is suppressed effectively.