Chemical modification of rigid poly(vinyl chloride) by the substitution with nucleophiles

The reaction of rigid poly(vinyl chloride) (PVC) with iodide, hydroxide, azide, and thiocyanate as nucleophiles (Nu) in ethylene glycol (EG) resulted in the substitution of Cl by Nu additional to the elimination of HCl, leading to the dehydrochlorination of the rigid PVC. High substitution rates were observed for hydroxide, azide and thiocyanate, while the addition of iodide accelerated predominately the elimination of HCl. The substitution by thiocyanate resulted at 150°C in both thiocyanate and isothiocyanate structures, whereas at 190°C, only isothiocyanate was observed in the polymer. The dehydrochlorination yield increased with an increasing molar SCN/Cl ratio, resulting in a maximum substitution at high molar SCN/Cl ratios. When EG was replaced by diethylene glycol (DEG) as solvent, the dehydrochlorination was found to be accelerated. It was assumed that DEG has a higher compatibility with PVC, making it easier to penetrate the rigid PVC particle. For triethylene glycol (TEG), the rapid dehydrochlorination resulted probably in the coverage of the surface of the PVC particle by methyl methacrylate/butadiene/styrene (MBS), preventing the penetration by the solution. The substitution/dehydrochlorination ratio decreased in the order of EG > DEG > TEG because of the declining polarity of the solvent, stabilizing the activated S_N2 complex. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Surface modification of polyvinyl chloride with biodegradable monomers

Graft copolymerization of sucrose acrylate (SA) onto 55 μm films of poly(vinyl chloride) (PVC) was investigated with benzophenone or 2,2′-azoisobutironitrile as the initiator. The grafting reactions were carried out in a closed cell containing the films to be treated with a solution of the sensitizer and the monomer. In this system, ultraviolet light through a quartz window initiated the reaction by exciting the initiator used. The grafting took place on a PVC surface layer, from the solution. The homopolymer formed during copolymerization was removed by washing. The percentage of grafting was determined by gravimetric measurements and by dye adsorption (crystal violet), and the characterization of PVC(g)SA was carried out by the use of infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. The weathering behavior of PVC(g)SA was studied with microorganisms in a growing medium, and the degradation was monitored by the weight loss of the films, FTIR, and SEM. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1195–1201, 1997     

外源添加物强化聚氯乙烯水热碳化脱氯

针对聚氯乙烯（PVC）垃圾难降解且焚烧处理会产生有毒物质造成环境污染等问题,本文提出了水热碳化技术处理的新途径。同时研究了不同外源添加物与PVC树脂协同水热碳化对提高脱氯效率的影响。结果显示生物质的添加可以促进PVC水热碳化反应中取代、消除、脱水和芳构化反应。当水稻秸秆与PVC树脂质量比为1.4、水热温度240℃、反应120min时,脱氯效率可达97.50% ± 1.40%,固相产物高位热值为39.57MJ/kg± 0.40MJ/kg,燃烧性能好。该技术为PVC垃圾转化成固体燃料、实现可持续利用提供了新思路,具有广阔的应用前景。     

二次反应最小条件下聚氯乙烯塑料脱氯过程的实验

采用金属网反应器对PVC热解过程中温度范围300～800℃、升温速率1～1000 K·s^-1、停留时间0～120 s的热解气体释放特性开展了实验研究.并基于EPA-26A标准对热解气中HCl和Cl₂进行了检测.结果显示,HCl和Cl₂的产率均随着温度的升高、停留时间的增长而有所提高.降低升温速率能够提升气态产物总体产率但没有改变含氯气体的总体分布.热解实验中气态产物均以HCl为主,并伴随有少量的Cl₂生成;该结果也证实了在PVC热解脱氯过程中大量含氯自由基的存在,进一步证实了PVC热解过程遵循的是自由基链反应机理.此外,通过对PVC热解焦样的分析进一步发现PVC热解第一阶段链反应终止时的分子更接近于直链多烯烃结构而非聚合环状结构,环化反应在该阶段并未发生.     

Chemical removal of residual monomer from polyvinyl chloride latices and slurries

Air quality standards are becoming increasingly stringent. Stripping and gas purging of the latex are no longer adequate to reduce dryer emissions of unreacted monomer below proposed limits. New technology has been developed in which the monomer is chemically removed from the latex before the drying step to reduce monomer emissions from the dryer and to lower monomer content in the product (1). Ozonation of vinyl latex is an effective technique because of its rapid reaction with double bonds. The short half life of ozone will result in no contamination of the product by unreacted ozone. Ozonation byproducts from the reaction with vinyl chloride are nontoxic and nonpolluting. Because the ozonation reaction is specific for double bonds, the polymer structure is left intact without affecting resin physical properties.     

基质增塑型吸水膨胀聚氯乙烯/氯化聚乙烯热塑性硫化胶的形态与性能

以交联聚丙烯酸钠( CPNaAA) 作为吸水材料,采用动态硫化法制备了聚氯乙烯( PVC) /氯化聚乙烯( CM) 共混型热塑性硫化胶( TPV) ,考察了基质PVC 的增塑对TPV 力学性能、微观形态、吸水性能及动态黏弹性能的影响。结果表明,在PVC 中添加邻苯二甲酸二辛酯增塑后,PVC/CPNaAA/CM TPV的拉伸强度、撕裂强度和硬度下降,但扯断伸长率明显增大; 基质的增塑使得PVC/CPNaAA/CM TPV 的吸水性能获得明显改善,且当基质PVC 中邻苯二甲酸二辛酯的用量为60 份( 质量) 时,TPV 在蒸馏水中浸泡200 h 的吸水率可达2 100%; 在应变扫描模式下,PVC/CPNaAA/CM TPV 出现了明显的Payne 效应,且随着基质增塑程度的提高,体系的Payne 效应有所减弱。     

2万t/a聚氯乙烯聚合后工序部分设备的改造

介绍对聚氯乙烯聚合中沉析槽,离心机进料方式,螺旋输送器及干燥塔段的改进,改进后树脂的质量有所提高,消耗降低,离心机运转正常,操作环境大大改进。     

丁腈橡胶增容丁苯橡胶/聚氯乙烯共混体系

采用一系列结合丙烯腈质量分数不同的丁腈橡胶(NBR)作为丁苯橡胶(SBR)／聚氯乙烯(PVC)不相容共混物的增容剂,研究了SBR／PVC／NBR硫化胶的力学性能,并用扫描电子显微镜、傅里叶变换红外光谱仪和动态黏弹仪研究了该硫化胶的形态结构与相容性。结果表明,结合丙烯腈质量分数为20％～26％的NBR是SBR／PVC的优良增容剂,可提高共混物的力学性能,使SBR相和PVC相达到微细均匀化分散,并在两相之间形成了界面层,使得增容效果达到最佳。     

Compatibility and nonlinear viscoelasticity of polychloroprene/polyvinyl chloride blends with nitrile butadiene rubber as a compatibilizer

Miscible polychloroprene/polyvinyl chloride (CR/PVC) blends with nitrile butadiene rubber (NBR) as a compatibilizer were prepared. The effect of NBR on the compatibility between CR and PVC was mainly analyzed by studying the thermal behavior and the phase structure of CR/PVC blends. An obvious decrement in the T_g of PVC phase successfully provided an explanation for the compatibilization of NBR. Due to the improved compatibility between CR and PVC, the size of PVC particles in CR/PVC blends decreased a lot according to the scanning electronic microscopic images. The significant improvement of mechanical properties of CR/PVC blends was in good agreement with the better compatibility between CR and PVC phases. The softening effect of NBR on the nonlinear viscoelasticity of CR/PVC blends was also studied by RPA 2000. Temperature sweep test by RPA 2000, a less reported characterization method of T_g, was successfully applied to measure T_g of CR/PVC blends and study the compatibilization of NBR. The reason for better thermal stability and the thermal decomposition mechanism of CR/PVC blends were analyzed according to the results of TGA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42448.     

Chemical modification of poly(2,6-dimethyl- 1,4-phenylene oxide) by electrophitic substitution reaction with isocyanates

Summary The chemical modification of poly(2,6-dimethyl- 1,4-phenylene oxide) (PPO) has been carried out by incorporating amide groups on PPO backbone by electrophilic substitution reaction with isocyanates. The modified polymers obtained have been characterized by IR and ^IH-NMR spectroscopy, nitrogen analysis, solubility tests and X-ray diffraction studies.NCL Communication No. 4455     

Chemical modification of polystyrene,III. Electrophilic substitution of polystyrene with aromatic anhydrides

Polystyrene has been chemically modified by Friedel-Crafts acylation reaction with trimellitic anhydride in the presence of anhydrous aluminium chloride as catalyst. The product has been characterized in respect of its structure and physicochemical properties by measuring its total capacity, thermal stability and the behaviour to pH metric titration. The thermal characteristics of the trimellitic anhydride modified polystyrene have been compared with the same for phthalic anhydride and pyromellitic dianhydride modified polystyrene in the light of their structural characteristics.     

Chemical modification of polystyrene. I. Electrophilic substitution of polystyrene with aromatic anhydrides

Polystyrene has been modified by electrophilic substitution reaction with phthalic anhydride and pyromellitic dianhydride. The products have been characterized by physical characteristics, solubility differences, elemental analysis, infrared spectra, ion-exchange capacity, and pH metric titration. The ultimate thermal stabilities of these modified polymers are better than the same for the unmodified polystyrene.     

Feasibility study of water as thinner for polyvinyl chloride plastisol

In the traditional formula of polyvinyl chloride (PVC) gloves, the diluent of PVC plastisol is usually organic solvent, which causes serious environmental pollution during the molding process. The aim of this study was to develop a low viscosity PVC plastisol emulsion (PDE) using water as a thinner by blending PVC emulsion (PVCE) with diisononyl phthalate (DINP) emulsion. DINP emulsion (DINPE) was prepared by a compound emulsifier of polyoxyethylene octyl phenol ether-10 and sorbitan monooleate. The effects of compound emulsifier concentration on the stability and microstructure of DINPE were investigated. The results showed that the optimal compound emulsifier concentration of DINPE was 10 wt%. In addition, the PDE obtained by blending exhibited a relatively uniform unimodal droplet size distribution. The steady state data revealed that the emulsions were shear-thinning pseudoplastic liquid. The effect of solid content and temperature on the apparent viscosity of PDE were also evaluated. The mechanical spectra obtained suggested the presence of weak gel structure in the PDE. The mechanical test results showed that the tensile strength and elongation at break of PVC film obtained by PDE were 12.62 MPa and 310.31%, respectively. This study demonstrated that water was effective in reducing the viscosity of PVC plastisol, which would promote the application of water thinner in glove production.     

Recovery of vinyl chloride from by-streams of polyvinyl chloride production by TPSA in a multitubular adsorber

This work aims at developing an efficient and feasible adsorption-based separation process for the separation of vinyl chloride and nitrogen, on activated carbon, by employing a multitubular packed bed geometry, with adsorbent material inside the tubes. Using this geometry, a 2-dimensional mathematical model of a temperature pressure swing adsorption process was used to developed a 6-step three multitubular adsorbers system capable of separating and purifying an industrial scale gas stream of a 40:60% (v/v) vinyl chloride/nitrogen mixture into a 95% (v/v) vinyl chloride stream and a nitrogen stream with a vinyl chloride limit concentration of 8 ppm (w/w). The process reported energy consumption of 4.88 × 10⁶ J/kg_VCM and recovery capacity of 24.35 kg_VCM/(m³_unit h). The multitubular geometry enabled the use of lower adsorbent loads, shorter cycle times, and lower regeneration temperatures. An equivalent 1-dimensional model has also shown to satisfactorily estimate the performance of the current equipment.     

交联剂DB对聚氯乙烯的交联改性

介绍了交联剂DB对聚氯乙烯的交联改性,讨论了各种因素对交联作用的影响.     

悬浮法聚氯乙烯干燥装置简介

介绍了国内采用的悬浮法生产聚氯乙烯用的干燥装置的干燥原理、工艺、设备和特点。     

Stress cracking of rigid polyvinyl chloride by plasticizer migration

Environmental stress cracking (ESC) (failure caused by crack and craze formation at a stress less than the yield stress) reduces the service life of many plastic products. This paper is concerned with ESC of rigid PVC products which are in contact with a plasticized PVC material. The ESC affect (as measured by elongation to break) is reduced at faster strain rates and by higher plasticizer viscosity, which suggests a mechanism requiring flow of plasticizer into a growing craze. Well fused (gelled) PVC made at a higher melt temperature slowed but did not eliminate environmental stress cracking. Rubber impact modifier added to the rigid PVC had no effect on ESC. Environmental stress cracking can be avoided by using flexible PVC that has a non-migrating plasticizer or by designing the product so that rigid PVC is not stressed while in contact with plasticized PVC.