氯乙烯聚合和聚氯乙烯改性分析

氯乙烯的聚合分为悬浮聚合、微悬浮聚合及乳液聚合,以悬浮聚合为主,一般来说共聚物是具有不同的化学组成分布和不通的分子量分布的一种高分子聚合物。高分子作为改性剂（聚合物改性剂）是共混物的一种应用,共混物是共和聚混物的简称。PVC改性有聚合改性、共混改性和复合改性,聚氯乙烯改性后可以生产更多产品,更好的满足人民的生活需求,     

氯乙烯聚合技术研究进展

对2009年美国《化学文摘》报道的氯乙烯自由基聚合、活性自由基聚合和茂金属催化聚合方面的论文和专利进行了综述。     

氯乙烯回流对悬浮聚合,微悬浮聚合及乳液聚合的影响

在聚合时氯乙烯单体的回流，与造成树脂大颗粒、表皮增厚、鱼眼增多、泡沫多、干燥困难、气相粘釜加重等有一定关系。为了减少季节变化对聚合的影响，采用在聚合釜中保留一定量的惰性气体或空气、釜顶部保温等措施，减少氯乙烯的回流。     

氯乙烯聚合用引发剂的研究

在研究单一引发剂分解动力学的基础上,提出复合引发剂分解动力学模型,并结合ＶＣＭ聚合动力学,为恒速聚合的复合引发体系的配方设计提供指导。     

氯乙烯悬浮聚合操作控制

文中叙述了在13．5m3、70m3釜氯乙烯悬浮聚合操作控制过程。     

国外氯乙烯聚合技术研究进展

总结了2006-2007年有关氯乙烯聚合技术的文献和专利,介绍了氯乙烯悬浮聚合、乳液聚合和新型聚合技术的研究进展(附56篇参考文献).     

新型引发剂在氯乙烯悬浮聚合中的应用试验

通过试验,对过氧化新戊酸叔己酯与偶氮二异庚腈两种引发剂在氯乙烯悬浮聚合中的应用进行了比较.结果表明:过氧化新戊酸叔己酯的反应活性和相对分子质量比偶氮二异庚腈略低,水溶性略大;在相同条件下,过氧化新戊酸叔己酯的残留率高;在用量(物质的量)相同的条件下,二者使用效果相当.     

氯乙烯悬浮(本体)聚合用过氧化物引发剂

介绍了氯乙烯(VC)悬浮(本体)聚合常用过氧化引发剂的合成方法，着重阐述引发剂与聚合动力学的关系以及聚合动力学的检测方法。研究了单一和复合引发剂条件下的VC聚合动力学，为优化引发剂体系、缩短聚合时间、提高聚合釜的生产能力提供理论基础。     

无机添加剂对氯乙烯悬浮聚合的影响

研究了添加未改性和表面改性的无机热稳定剂和CaCO3对氯乙烯悬浮聚合过程的影响,发现采用硅烷和铝酸酯改性无机热稳定剂和采用硬脂酸改性CaCO3,可以达到良好的表面有机改性效果．改性剂最佳质量分数为1．0％左右;热稳定剂对聚合起延缓作用,使一定压降(AP)时的聚合时间增加5～120min、转化率下降3．6％～17．5％;但经表面改性后,对聚合的延缓作用减弱;CaCO3使聚合△P提前10～20min,使一定△P时的聚合转化率下降2．4％～17．5％,但对实际聚合速率的影响不大。     

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     

氯乙烯聚合研究进展

对近期氯乙烯聚合研究进展情况进行了综述,在聚合化学方面的研究包括复合引发剂引发氯乙烯聚合动力学、氯乙烯活性自由基聚合、茂金属催化聚合和阴离子聚合,在成粒机理方面的研究包括氯乙烯悬浮聚合和新型非均相聚合机理。     

Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties

Continuous dosing of a fast initiator during the suspension polymerization of vinyl chloride has been carried out in a pilot‐scale reactor. The kinetics course of this polymerization and the particle features of the resulting grains were discussed and compared to the conventional polymerization with the same conversion and maximum reaction rate. It was found for the system used that a suitable dosage trajectory allows the reaction rate to remain constant during polymerization. This decreases the polymerization time up to 53% compared with the conventional suspension polymerization, while the molecular weight distribution and molecular weight of the final grains remained almost unchanged. SEM micrographs revealed that PVC grains prepared using this polymerization process had irregularly shaped, uneven particle surfaces and larger particle sizes. The grains also featured high porosity with loosely aggregated smaller primary particles that led to low levels of residual unreacted monomer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44079.     

Dispersion of nanoparticles in poly(vinyl chloride) grains during In situ polymerization

Inorganic nanoparticles such as calcium carbonate, silica, or hydrotalcite were dispersed in vinyl chloride prior to suspension polymerization. That led to the production of poly(vinyl chloride) (PVC) composite grains with higher porosity and different internal morphology from those of commercial PVC. The PVC/composite grain sizes and their distribution were also influenced by the presence of nanofillers. The distribution of filler nanoparticles (either calcium carbonate or silica) was not uniform throughout the PVC grains. Regions of high and low filler concentration were observed. Regions of pure polymer were also observed. Reasons for that are suggested. Hydrotalcite did not remain in the PVC grains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012