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。     

新型过氧化物引发剂引发氯乙烯悬浮聚合动力学

研究了新型过氧化物引发剂过氧化新癸酸 1,1 二甲基-3-羟基丁基酯(Lup 610)在51.3与56.8℃以及过氧化新庚酸叔丁酯(Lup 701)和过氧化新戊酸叔己酯(HPV)在61.8℃单一引发剂引发氯乙烯悬浮聚合动力学,并采用模型计算结果绘制转化率 时间曲线,取与实验数据符合最好的f值作为引发剂的引发效率,求得引发剂Lup 610在51.3与56.8℃的引发效率分别为0.80与0.75,引发剂Lup 701和HPV在61.8℃下的引发效率分别为0.55和0.50。研究了上述引发剂与过氧化二碳酸二(2-乙基己酯)、过氧化新癸酸叔丁酯在各温度下复合引发剂引发氯乙烯悬浮聚合的动力学,与模型值相比较,发现两者能很好吻合。     

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。     

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.     

复合引发剂存在下的氯乙烯聚合动力学

Kinetic models for the rate constants of vinyl chloride polymerization in the presence of initiator mixtures were proposed. They may be used to design the initiator recipes for the vinyl chloride polymerization with uniform rate at different temperatures at which various grades of poly(vinyl chloride) will be prepared.     

氯乙烯悬浮聚合过程引发体系优化

在氯乙烯悬浮聚合过程机理模型的基础上,建立了复合引发体系的优化模型,并进行了二元引发体系的优化研究,得到了不同引发剂配比下的最大聚合速率等高线和临界转化率时的聚合时间等高线。结果可以用来指导复合引发剂的配方设计,有助于聚合热的均匀释放、聚合釜冷却能力的充分利用和聚合釜生产率的提高。     

新型高效引发剂过氧化二碳酸二（十六烷酯）在氯乙烯悬浮聚合中的工业性应用

1 前言 随着聚氯乙烯工业的迅速发展,越来越迫切地需要综合性能优良的引发剂,即活性高,放热均匀,易贮运。在我国的氯乙烯悬浮聚合中,普遍使用的高效引发剂为EHP(过氧化二碳酸—2乙基己酯)。EHP虽然活性高,放热均匀,但它在常温下为液体,易分解,保存和运输较难。许多聚氯乙烯生产     

氯乙烯悬浮聚合复合引发剂体系的中试研究

提出了生产3种牌号PVC树脂的复合引发剂配方。中试结果表明:采用悬浮法生产S-700、S-1000和S-1300 PVC树脂时宜分别采用Tx-36和Tx-23、EHP和Tx-99、Tx-99和Tx-23复合过氧化物引发剂体系,聚合时间可控制在3.2~3.8 h,反应过程平稳,反应速率快,生产的PVC树脂质量优良。     

新型氯乙烯非均相聚合动力学和成粒机理

对以正丁烷（But)为反应介质的新型氯乙烯（VC）非均相聚合动力学和成粒机理进行了研究，根据VC-But二元体系气液平衡方程，由聚合过程气相压力或组成变化计算VC聚合转化率，VC非均相聚合的诱导期不明显，自动加速现象一般发生在聚合前、中期，后期聚合速率较小，新型VC非均相聚合PVC树脂的体粒径与悬浮PVC树脂相当，数均粒径较小，PVC颗粒由基本不熔结的初级粒子组成，颗粒内部初级粒子分布密度大，粒径大，孔隙率高；而在颗粒表层初级粒子分布密度高，粒径小，孔隙率低；树脂的增塑剂吸收率远大于悬浮PVC树脂，根据PVC树脂的颗粒特性和PVC与VC／But混合液的溶解度参数差异，推断聚合成粒机理为：PVC分子链在很低转化率时就从聚合介质中沉析出来并聚集形成微区，初级粒子和颗粒；后期成粒过程包括颗粒内部初级粒子的增长和向表层的离心聚集，颗粒对新形成的大分子链及其初级聚集体的捕捉等。     

分散剂和非离子型表面活性剂对悬浮聚氯乙烯树脂颗粒特性的影响

研究了聚乙烯醇(PVA)分散剂和非离子型表面活性剂对悬浮聚氯乙烯(PVC)树脂颗粒特性的影响。结果表明随着PVA醇解度的增加，PVC树脂的颗粒规整性和表现密度增加，孔隙率和吸油率降低；随着非离子型表面活性剂添加量的增加，PVC树脂的平均粒径和吸油率增大。从PVA和表面活性剂在水一油两相分配出发，讨论了PVA醇解度和添加非离子型表面活性剂对PVC树脂的颗粒特性影响机理。     

An experimental investigation of poly(vinyl chloride) emulsion polymerization: Effect of initiator and emulsifier concentrations on polymerization kinetics and product particle size

Effects of concentration changes in initiator species Na₂SO₃, (NH₄)₂S₂O₈ and CuSO₄, and emulsifier, ammonium stearate, on poly(vinyl chloride) (PVC) emulsion polymerization kinetics and on product particle size were experimentally investigated. It was observed that to obtain industrially significant rates and overall conversions, not only an optimum concentration ratio of Na₂SO₃/(NH₄)₂S₂O₈/CuSO ₄ must be used, but also the concentrations of these species must be above certain limits. Increasing the concentration of the emulsifier used did not influence the rate of polymerization, but led to increases in limiting conversions. Product particle size analyses indicate that average particle size is independent of initiator concentration and rate of initiation. An increase in the emulsifier concentration on the other hand appears to lead to an increase in number of particles in the system and thus promotes smaller particle sizes.     

悬浮态乳液聚合条件对聚氯乙烯树脂颗粒特性的影响

Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.     

Influences of some polymerization conditions on particle properties of suspension poly(vinyl chloride) resin

Effects of polymerization temperature, conversions, and nonionic surfactant on the particle properties of suspension poly(vinyl chloride) (PVC) resins were investigated. It was shown that polymerization temperature has no significant influences on the mean particle size of PVC resin, and that the cold plasticiser absorption (CPA) of resin decreases linearly with the increase of polymerization temperature. Agglomeration of VCM droplets finishes before 20% conversion, and the mean particle size keeps almost constant at later stages of the polymerization process, but the CPA continues decreasing with the increase of conversion. Scanning Electron Microscopy (SEM) micrographs show that the degree of agglomeration of primary particles increases with polymerization temperature and conversion. Addition of nonionic surfactant to the VCM suspension system, as a secondary suspending agent, has a great influence on the particle properties of PVC resin. The particle size and CPA increase as the concentration of nonionic surfactant increases. The nonionic surfactant with a greater HLB value is more effective in raising the mean particle size, but is less effective in raising the CPA. It is considered that the added nonionic surfactant would be absorbed faster on the VCM/water interface than the poly(vinyl alcohol) (PVA), which was used as the primary suspending agent. Because the colloid protection ability of the nonionic surfactant is less than that of PVA, droplets become less resistant to coalescence, and the mean particle size of the final PVC resin increases consequently. The increase of porosity is caused by the combined effects of increased coalescence of VCM droplets and the nonionic surfactant's steric effect inside the droplets. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1544–1552, 2002     

硬聚氯乙烯低发泡挤出成型研究

采用自由发泡挤出的方法研究了硬聚氯乙烯低发泡挤出成型的配方设计和工艺条件控制。讨论了稳定剂品种，改性剂品种和发泡剂用量对制品密度，泡孔结构以及外观表面的影响。还揭示了口模温度和螺杆转速与制品密度的关系。     

原位聚合聚氯乙烯树脂的合成及性能

研究了氯乙烯悬浮聚合时添加氯化聚乙烯(CPE)冲击改性剂、CaCO3填料、润滑剂及热稳定剂对聚合反应的影响，并对得到的可直接加工的原位聚合聚氯乙烯(RTUPVC)树脂的性能进行了表征。结果发现：CPE和CaCO3的加入均使达到相同压降的聚合时间缩短，氯乙烯聚合转化率相应减小；RTUPVC树脂的粒径随CPE粒径和用量的增大而增大，而CaCO3含量对RTUPVC树脂粒径影响不大；润滑剂和热稳定剂的加入，对聚合反应起延缓作用，但对RTUPVC树脂粒径影响不大；RTUPVC树脂加工塑化时间随CPE含量的增加而减少；相同CPE用量时，RTUPVC树脂的冲击强度和拉伸强度明显高于PVC/CPE共混物。