氯乙烯聚合粗料的产生原因及对策

分析了在PVC聚合反应过程中形成粗料的原因,总结出预测粗料产生的趋势分析法,提出了避免粗料产生的改进措施。     

氯乙烯聚合装置报警的管理及优化

针对氯乙烯聚合装置报警泛滥问题,对报警进行了分级管理及优化,抑制了无效报警,提升了操作人员对有效报警的响应速度。     

聚氯乙烯发生粗料的原因分析及预防措施

本文在简单分析了聚氯乙烯发生粗料的原因后,提出了预防措施。     

高浓度甲醛发生聚合的原因及应对措施

在工业生产过程中,由于生产环境和储存方法不得当,高浓度甲醛溶液(37％～55％)会自动聚合形成一种白色固体,能引发甲醛管线、仪表和容器的堵塞,严重地影响甲醛产品的生产和使用,甚至给企业造成巨大的经济损失.介绍了甲醛聚合的原理及诱发原因,并结合生产实际从多个方面对预防甲醛聚合进行了总结,对企业高浓度甲醛质量的稳定性及生产正常运行都有极强的参考价值.     

氯乙烯转化器的泄漏原因及改进措施

论述了电石法生产氯乙烯过程中转化器的腐蚀原因，探讨了腐蚀机理，并提出了解决的办法。     

试论氯乙烯聚合粘釜的形成及防范技术措施

本文首先析了氯乙烯聚合粘釜的形成、防粘机理及危害性,同时提出了预防PVC聚合釜防粘釜技术措施,最后给出了防粘釜技术的发展趋势,可供相关技术人员参考.     

试论氯乙烯聚合粘釜的形成及防范技术措施

本文首先析了氯乙烯聚合粘釜的形成、防粘机理及危害性,同时提出了预防PVC聚合釜防粘釜技术措施,最后给出了防粘釜技术的发展趋势,可供相关技术人员参考。     

粗氯乙烯制酸工艺改进

介绍了对电石法PVC生产中典型制酸工艺的技术改进内容,经过改进提高了副酸浓度,降低了生产成本,改善了环境面貌。     

氯乙烯自聚原因分析及预防措施

分析了氯乙烯自聚的原因及危害,并提出了解决措施:①将原来的注水管线直接入釜改造为注水管线连接到氯乙烯单体入料调节阀之后;②选择阻聚剂的类型,调整阻聚剂的用量,从源头减少氯乙烯单体中的酸性物质和水等;③降低系统中的氧含量;④降低回收系统和单体槽的温度,加强单体槽的排水。     

氯乙烯生产控制系统的改造

介绍了横河公司的分布式控制系统CS3000在氯乙烯生产过程中的应用情况,阐述了该系统的工艺流程、硬件配置、软件配置和主要功能。     

氯乙烯增压机振动故障分析及对策

简述了 PVC生产中氯乙烯深度脱水工艺增压机的使用现状,重点针对增压机机体及管道异常振动情况,通过制定振动测试方案及现场测试数据分析,找出了引起故障原因,并提出了相应的减振措施,取得了较好的运行效果.     

氯乙烯聚合中突然降温现象的探讨

探讨了在氯乙烯种子乳液聚合与氯乙烯微悬浮聚合(小试)实验中突然降温现象的形成原因及其特点。     

本体法氯乙烯聚合釜搅拌试验分析

通过试验研究了搅拌器功率特性和流动状态,分析了本体法氯乙烯聚合的预聚合釜和聚合釜的搅拌性能。     

Bulk polymerization of vinyl chloride

The bulk polymerization of vinyl chloride initiated by AIBN at temperature levels of 30°, 50°, and 70°C has been studied. Molecular weight averages and distribution (MWD) were measured by gel permeation chromatography. A model has been proposed which accurately predicts conversion to high levels and MWD. Molecular weight measurements show that transfer to monomer plays the important role in controlling molecular weight averages. Disproportionation is probably the dominant mode of termination.     

Kinetics of vinyl chloride and vinyl acetate emulsion polymerization

The kinetics of vinyl chloride and vinyl acetate emulsion polymerization are reexamined. The validity of Ugelstad's model for systems with high desorption rate is confirmed by simulating conversion histories for both systems at different initiator concentrations and particle numbers. On the basis of the model, it is shown that at ordinary initiation rates, termination reactions are unimportant with respect to molecular weight development in both systems, and as a consequence, molecular weight development is independent of number and size distribution of polymer particles and of initiator and emulsifier level. Based on this conclusion, it is shown that in accordance with experimental facts, the molecular weight distribution obtained in vinyl chloride emulsion polymerization is the most probable distribution, and it is concluded that the number of long-chain branch points per repetition unit is less than 2 × 10^?4 at high conversions. In vinyl acetate emulsion polymerization, an almost logarithmic normal distribution is obtained. The distribution is strongly broadened by branching reactions with the number of long-chain branch points increasing rapidly with monomer conversion. The increase of M_n with increasing conversion is due to terminal double-bond polymerization, while the increase in M_w is due mainly to transfer to polymer.     

The mechanism of the formation of chloromethyl side groups in vinyl chloride polymerization

Summary The dependence of the content of short branches on the monomer and initiator concentrations in vinyl chloride polymerization has been investigated by infrared examination of polymers reduced with tributyl tin hydride. The branch content increases with decreasing monomer concentration but appears to be independent of the initiator concentration. The findings best fit the mechanism of RIGO et al (1972) involving head-to-head addition followed by migration of the end chlorine atom.     

Experimental investigation of vinyl chloride drop behavior during suspension polymerization

The effects of some polymerization conditions on poly(vinyl chloride) (PVC) particles produced by the suspension polymerization process were studied on a laboratory scale. The different stages of vinyl chloride suspension polymerization were investigated experimentally by using an on-line sample withdrawal technique during reaction. It was found that the method of addition of initiator has a great effect on the PVC particle uniformity as well as the size distribution. Furthermore, when the initiator was predispersed in the continuous phase, some latex particles were formed. The effect of the type of stabilizer was also studied with two different types of PVA [partially hydrolyzed poly(vinyl acetate)]. It was found that by changing the stabilizer, the particle size, the porosity, and the morphology could change. When H80 (PVA with a degree of hydrolysis of 80% and a molecular weight of 259,000) stabilizer was used, the rigidity of the PVC particles was weak. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 127–134, 1997