氯乙烯/纳米CaCO_3原位聚合PVC树脂的加工性能研究

采用纳米CaCO3的微乳化分散技术制得了一种新型氯乙烯/纳米CaCO3原位聚合PVC树脂。对该PVC树脂的流变性能、热性能和微观结构等进行了研究。实验结果表明:这种新型PVC树脂在较高剪切应变下,熔体扭矩的下降幅度比通用PVC树脂增加了近一个数量级,在Haake流变仪上测得塑化熔融时间从通用PVC树脂的6 min缩短到2.5 min。这种新型PVC树脂的微商热失重曲线(DTG)的失重速率变化最大温度从299℃上升到320℃,维卡软化点上升了9℃。此外电子显微镜测试结果表明,纳米CaCO3在PVC树脂基体内呈现了小于100 nm颗粒的均匀分散。     

氯乙烯/纳米CaCO3原位聚合PVC树脂的加工性能研究

采用纳米CaCO3的微乳化分散技术制得了一种新型氯乙烯/纳米CaCO3原位聚合PVC树脂.对该PVC树脂的流变性能、热性能和微观结构等进行了研究.实验结果表明：这种新型PVC树脂在较高剪切应变下,熔体扭矩的下降幅度比通用PVC树脂增加了近一个数量级,在Haake流变仪上测得塑化熔融时间从通用PVC树脂的6 min缩短到2.5 min.这种新型PVC树脂的微商热失重曲线（DTG）的失重速率变化最大温度从299 ℃上升到320 ℃,维卡软化点上升了9 ℃.此外电子显微镜测试结果表明,纳米CaCO3在PVC树脂基体内呈现了小于100 nm颗粒的均匀分散.     

基于工业化生产的纳米CaCO3原位聚合PVC颗粒特性控制技术

通过微乳化分散技术使纳米CaCO3实现了良好分散，用于氯乙烯原位悬浮聚合，制得性能优异的纳米CaCO3原位聚合PVC树脂。考察了纳米CaCO3含量对氯乙烯原位聚合成粒过程的影响，建立了纳米CaCO3含量、反应器搅拌强度以及聚合配方中分散剂含量与PVC颗粒平均粒径的数学关联式。以上研究结果已应用于6万t／a工业装置，文中还列举了30m3以上大釜的纳米CaCO3原位聚合PVC生产实例数据。     

基于30m~3聚合釜的纳米CaCO_3原位聚合PVC树脂颗粒特性预测与优化

通过微乳化分散技术使CaCO3实现良好分散,通过氯乙烯原位悬浮聚合制得了纳米CaCO3微乳化法原位聚合PVC树脂(简称纳米PVC树脂)。为解决纳米PVC树脂的颗粒形态控制难题,提出了基于组合神经网络的软测量方法,建立了纳米PVC树脂颗粒特性的软测量预测模型,应用效果表明该软测量模型能较准确地预测纳米PVC树脂的平均粒径。利用该软测量预测模型在30 m3聚合釜上实现了纳米PVC树脂颗粒特性优化,制得具有较理想颗粒特性的纳米PVC树脂。     

高耐热性的纳米CaCO3原位聚合PVC树脂新产品

在工业化反应装置上开发成功了氯乙烯原位悬浮聚合技术,得到了新品种的高耐热性的纳米CaCO3原位聚合PVC树脂。185℃刚果红试纸变色时间试验证明,纳米复合PVC树脂热分解时间比传统产品延长了近10倍。提出的机理模型是部分纳米CaCO3粒子在原位聚合过程中发生了崩解,界面上会出现具有很高化学活性的不饱和键态结构,这使得纳米CaCO3同时具有了中和PVC分子降解过程放出的HCl、取代PVC链上不稳定氯原子、加成大分子中不饱和双键等三大热稳定功能。介绍了用傅立叶变换红外光谱(FTIR)、差示扫描量热(DSC)和透射式电镜(TEM)等手段对以上机理的验证结果。     

纳米CaCO_3的接枝改性及其填充PVC复合材料的性能

采用表面原位接枝聚合在纳米CaCO3颗粒表面引入聚甲基丙烯酸甲酯(PMMA)或聚丙烯酸丁酯(PBA),用共混法制备了纳米CaC03/PVC复合材料,研究了不同界面特性时纳米CaCO,/PVC复合材料的力学性能.研究结果表明:通过表面原位接枝聚合反应可以在纳米CaCO3颗粒表面接枝PMMA和PBA;表面接枝聚合改性大大促进了纳米CaCO3粒子在PVC基体中的分散行为,增加了复合材料的拉伸强度以及与聚合物的界面粘接强度,但复合材料的冲击强度有所下降.     

原位聚合PVC／CaCO3纳米复合树脂剪切变稀现象的加剧与加工节能效应

简述了原位聚合PVC／CaCO3纳米复合树脂的制备方法与性能,通过毛细管流变仪考察了不同纳米CaCO3用量下PVC纳米树脂剪切速率对剪切黏度的影响,探讨了加工过程中PVC纳米树脂剪切变稀的机制并给出了加工应用实例,展望了PVC纳米树脂的发展前景。结果表明：加工过程中采用PVC纳米树脂可降低设备的能耗,具有很好的发展前景。     

PVC的微发泡处理及PVC/CaCO3的原位复合

研究了用原位生成法制备PVC/纳米CaCO3复合母粒的过程. 首先利用混合溶剂将PVC粉料溶胀,同时带入发泡剂偶氮二异丁腈,在112oC下进行固相微发泡. 利用已发泡的PVC,采用原位生成法制备了纳米CaCO3/PVC复合母粒. 通过扫描电镜观察,发现已发泡PVC颗粒表面布满微孔,纳米级CaCO3填充在PVC孔洞里. PVC/纳米CaCO3复合母粒同时起到了增韧增强的作用.     

纳米CaCO3微乳液存在下的万吨级氯乙烯原位聚合技术

成功开发了一种聚合级纳米CaCO3微乳化体系,可直接用于氯乙烯（VCM）的原位聚合。当体系与VCM比例在3％－5％时,所得PVC－SG5型树脂白度为86,表观密度为0．59g/mL,吸油率达到25％左右,PVC树脂加工流变性能比传统产品有大幅提高,制品的冲击性能增加2－4倍。电镜显示纳米颗粒与PVC基体之间呈三维网架结点结构,在高分子基体内部分纳米颗粒崩解为5－10nm的粒子。该项技术解决了纳米微乳化体系稳定性的问题,并初探了纳米原位聚合反应动力学和成粒过程的影响因素。已先后在国内2万t/a工业装置及6万t/a生产流程实现了产业化。     

纳米PVC树脂有机/无机相结构组装特征及其形成机理研究

用TEM和AFM研究了纳米CaCO3与VCM的原位聚合，发现无机纳米相与PVC有机相结构的组装具有三大典型特征；核壳型，崩解型及微胶囊型，分析了核壳型结构是聚合反应之前纳米颗粒作为无机分散剂吸附在VCM液滴表面形成的：崩解型是VCM单体进入纳米颗粒孔道，发生聚合反应后热量积聚造成的；而微胶囊结构则是纳米颗粒表面在冷分散阶段浓集了引发剂，升温聚合时，纳米颗粒作为提供游离基的刚性骨架，产生了诸多毛杆高分子后形成的结果。     

Small-angle scattering studies of PVC and PVC blends

Small-angle X-ray and small-angle neutron scattering studies have been carried out on poly(vinyl chloride) (PVC), and blends of PVC with solution-chlorinated polyethylene (SCPE) and poly(butyl acrylate) (PBA). The PVC used was commercial (suspension-polymerized) or bulk-polymerized. The blends of PVC with PBA were prepared by solvent-casting and those with SCPE by in situ polymerization. PVC samples show shoulders in the scattering spectra, presumably due to crystallites, which persist even in samples which have been solvent cast. Blends of PVC with PBA also show a peak but at a higher ‘d’ spacing. The blends with SCPE which were prepared by in situ polymerization show no such peak. This suggests that the method of preparation prevents the formation of crystallites. An increase in scattering of the PBA blends was observed when the samples were heated to the temperature of phase separation. Neutron scattering studies were also carried out using 2% deuterium labelled PVC in PVC and in the blends. In the PVC this showed chain dimensions in good agreement with predicted values. In the blends, dimensions of the same order were obtained, confirming a molecular dispersion of chains in the single phase, but there was an apparent reduction in the chain dimensions. This could be explained by a true reduction in dimensions or a non-zero A₂ value in the blends.     

Microcellular PVC

Novel microcellular PVC foams with a very homogenous cell distribution and cell densities ranging from 10⁷ to 10⁹ cells/cm³ have been created using carbon dioxide as the nucleating gas. Microcellular foams with relative densities (density of foam divided by the density of unfoamed polymer) ranging from 0.15 to 0.94 have been produced. It was found that the bubble nucleation density has and Arrhenius-type dependence on temperature, while the average bubble diameter is relatively independent of the foaming temperature. A majority of the cell growth was found to occur in the early stages of foaming.     

Miscibility of PVC with chlorinated PE and chlorinated PVC

Miscibility of PVC with chlorinated PE and chlorinated PVC was reviewed. The miscible region of chlorine content ranged from 44 wt% to 65 wt%, which was not symmetric to the chlorine content of PVC, 56.7 wt%. Two group contribution methods were used to calculate solubility parameters of polymers. The results of solubility parameters showed a more symmetric miscible region with respect to the value of PVC. However, the ranges of miscibility were different. It was 2.3 (J/cm 3 ) 0.5 in a three-dimensional method and was 1.5 (J/cm 3 ) 0.5 in the Fedors method.     

PVC加工业对PVC树脂的需求及发展前景

简述了世界合成树脂的生产状况及目前国内PVC加工企业的概况，提出了加工企业对树脂的要求，介绍了几种对我国关系重大的特种树脂，分析了PVC树脂加工企业的发展动态，并对其发展前景进行了展望。     

聚氯乙烯生产过程中聚氯乙烯粉末回收探讨

介绍了聚氯乙烯生产过程中离心母液水及干燥外排尾气中聚氯乙烯粉末的回收情况。以30万t/a聚氯乙烯装置为例,回收离心母液水中的聚氯乙烯粉末约352.8 t/a,回收干燥后外排尾气中的聚氯乙烯粉末约131.2 t/a。     

纳米晶PVC在PVC／CaCO3复合材料中的作用

研究了不同粒径的纳米晶PVC的增韧、增强作用及对纳米CaCO3改性时偶联剂对材料力学性能的影响。结果表明：两种粒径的纳米晶PVC均能起到显著的增韧和增强作用，且粒径小的纳米晶PVC作用更明显。材料拉伸强度、冲击强度随偶联剂含量的增加而提高。纳米晶PVC和纳米CaCO3使复合材料达到工程材料的标准。     

PVC抗冲改性剂

详细论述了PVC(聚氯乙烯)抗冲改性剂的改性机理、组成物类型、品种开发现状、应用特征及加工者选择抗冲改性剂的基本准则。     

PVC and sustainability

PVC has been under intense and hostile attack for a number of years, primarily because of its association with chlorine chemistry. It has been argued by some that because of this association it is inherently unsustainable, although much of this argument has been emotionally driven rather than based upon scientific scrutiny. Yet the presence of chlorine imparts a range of unique technical features in PVC that set it apart from many other polymers. A number of these features are well known and documented, and perhaps this uniqueness makes it a fascinating polymer to study in terms of its potential for sustainability. It is durable in use and difficult to break down. This persistence has made it a target by some campaigners, yet this could arguably be one of its greatest strengths from a sustainability perspective. The following report assesses—on a scientific basis—what sustainability means to the PVC industry and the necessary steps that would be needed to deliver a truly sustainable polymer. The evaluation model presented is based on The Natural Step (TNS) framework. The TNS framework is a robust and science-based set of tools that define sustainability in unambiguous and workable terms and helps organisations engage with the practicalities of sustainable development. In particular, the study includes a case history of a sustainable development process leading up to this evaluation involving a number of leading UK retailers.