宽分子量分布高聚合度PVC的合成和性能

Synthesis of High Polymerization Degree Poly (vinyl chloride) With Wide Molecular Weight Distribution

针对高聚合度聚氯乙烯(PVC)加工性能较差的缺点,采用2段聚合温度法合成了宽分子量分布的PVC树脂,并对树脂的热稳定性、加工性能和力学性能进行了研究。研究表明:采用过氧化二碳酸二环已酯(DCPD)、过氧化十二酰(LPO)引发剂复合,并在向高温段升温前加入巯基乙醇消耗残留DCPD,能通过低温、高温段聚合制备宽分子量分布高聚合度PVC,其平均聚合度和分子量分布是低温段聚合温度和时间、高温段聚合温度和时间及巯基乙醇浓度的函数。宽分子量分布高聚合度PVC的热稳定性与聚合度接近的恒温聚合PVC相当,其加工性能随分子量加宽而变好,拉伸强度和伸长率基本不受分子量分布的影响。

High polymerization degree poly (vinyl chloride) (HP - PVC) with wide molecular weight distribution (MWD) was synthesized with the two - stage polymerization temperature process aimed at improving the processability of PVC. The thermal stability, processability and mechanical properties of HP - PVC were studied. DCPD/ LPO were used as composite initiators in the synthesis of HP - PVC and mercaptoethanol was added to eliminate the residue of the initiator before raising reaction temperature from low to high stage. The average polymerization degree and MWD of the HP - PVC so prepared were the functions of the polymerization temperature and time in low and high stage as well as the concentration of mercaptoethanol. The thermal stability of HP - PVC was comparable to that of the PVC with similar polymerization degree but polymerized at constant temperature. The processability of HP - PVC was improved as MWD was increased. The tensile strength and elongation of HP - PVC was hardly influenced by the increment of MWD.