聚氯乙烯(PVC)合成化学的进展主要聚焦于内增塑和减少分子链缺陷结构。对于前者,方法包括:利用PVC分子链中C—Cl键的亲核取代反应及后续的点击反应等引入小分子增塑官能团;利用活性C—Cl键的接枝聚合引入大分子接枝链;自由基共聚合引入自增塑功能单体,如氯乙烯与(甲基)丙烯酸酯聚乙二醇单甲醚酯的共聚物展现出了优异的内增塑性能;可控自由基聚合合成嵌段聚合物等。这些方法虽然制备了不同玻璃化转变温度(Tg)的PVC共聚物,但反应物的高成本和工艺过程的复杂性,在工业生产中的应用还存在挑战。在工业生产技术方面,讨论了影响PVC树脂颗粒特性的工艺因素,重点介绍了连续引发剂加入(CiD)技术。CiD技术可以将PVC的聚合反应时间缩短到240min,同时通过降低叔氯的含量而显著提高PVC产品的热稳定性。作为平衡氯碱工业氯气的主要产品,PVC树脂在较长的一段时间是不可替代的,提升生产技术和改进产品质量,开发新的PVC共聚树脂是行业可持续发展的关键。
This article reviewed the main progresses of poly(vinyl chloride) and focused on developing internal plasticization and reducing molecular chain defects.For the former,the solution includes:(1)the introduction of small_molecule plasticizing functional groups using nucleophile substitution reactions of C—Cl bonds in the PVC molecular chain and subsequent click reactions,etc.;(2)the introduction of large molecule graft chains using graft polymerizations of reactive C—Cl bonds;(3)the introduction of self_plasticizing functional monomers through free radical copolymerization,such as copolymers of vinyl chloride and (meth)acrylate polyethylene glycol monomethyl ether ester exhibited excellent internal plasticizing properties;and (4)controlled free radical polymerization synthesized block polymers,etc.The above technologies successfully produced PVC copolymers with varying glass transition temperatures (Tg).However,the high cost of the reactants and complicated operations made their application in industrial production challenging.In terms of industrial production technologies,the process factors affecting the grain morphology were discussed,with a focus on the continuous initiator dosing (CiD) technology,which could shorten the polymerization reaction time of PVC to 240min and significantly improved the thermal stability of PVC resins via reducing the content of tertiary C—Cl of the PVC chains.As a very important polymer to balance the chlorine of chloro_alkali industry,PVC resin remains irreplaceable for a considerable period.Improving production technologies,enhancing product quality,and developing new PVC copolymer resins are crucial for the sustainable development of the industry.
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