氯乙烯悬浮聚合的宏观成粒过程

采用冷冻取样法研究了氯乙烯悬浮聚合中聚氯乙烯树脂的宏观成粒过程,发现在低转化率时粒径随转化率的增加而逐渐增大,当转化率达到15%以后,粒径则几乎不再变化;也研究了搅拌转速、分散剂用量和聚合温度等对粒径变化的影响,为聚合配方与操作条件的确定以及树脂的最终粒径与粒径分布的控制提供参考,并为聚合釜的设计提供依据。     

汽车仪表板表皮专用ABS树脂中试技术研究

汽车仪表板表皮专用ABS树脂是一种综合性能指标和技术含量很高的ABS树脂,用于制备中低档轿车、中型车和卡车的仪表板表皮。作者主要考察了中试放大后聚合反应单体转化率随时间的变化规律及搅拌转速对胶乳粒径大小及分布的影响,以及接枝聚合过程中大小粒径PBL掺混比例、TDDM、FES对产品性能的影响,产品质量超过美国Blendex 131产品水平。     

悬浮法PVC树脂粒径的影响因素

讨论了悬浮法PVC树脂生产过程中影响树脂粒径的主要因素,有针对性地从聚合釜搅拌、反应配方、体系氧含量、pH值、聚合温度和转化率等方面提出了粒径的控制方案。     

偏氯乙烯-氯乙烯悬浮共聚树脂的颗粒特性

在5L聚合釜中制备了偏氯乙烯(VDC)一氯乙烯(VC)共聚树脂,研究了起始搅拌转速、分散剂配比、水油比和助剂对共聚树脂颗粒特性的影响。实验结果表明,随着起始搅拌转速的增加,树脂粒径增大,而粒径分布变宽;增加复合分散剂中纤维素醚K的配比,树脂的平均粒径增大;增加水油比,树脂颗粒的粒径变小,分布变窄;聚合前加入助剂环氧大豆油(ESO)对树脂颗粒的粒径及分布影响不大。本实验制备的树脂颗粒形态规整,与日本同类产品相近。     

乙基葡萄糖苷的催化合成与分离

在搅拌釜式间歇反应器中研究了在磺酸型阳离子交换树脂催化下葡萄糖和乙醇的非均相催化反应. 实验考察了催化剂种类、粒度、搅拌转速、用量和反应温度对转化率的影响. 初步确定了催化反应条件：温度78℃,搅拌转速300 r/min,树脂粒度50~80目,树脂:葡萄糖为1:1,反应20 h转化率可达89%. 另外,建立了利用吸附树脂分离乙基葡萄糖苷的新方法.     

偏氯乙烯—丙烯酸甲酯悬浮共聚树脂颗粒特性的研究

在5升釜中进行偏氯乙烯—丙烯酸甲酯悬浮共聚.研究了分散剂浓度、搅拌转速、聚合温度以及水油比等因素对树脂颗粒特性(平均粒径及分布、表观密度)的影响.     

悬浮法聚氯乙烯树脂的颗粒特性及其影响因素的研究

在50升氯乙烯聚合釜中,研究了搅拌型式、搅拌强度、分散剂种类和用量、水油比对树脂平均粒径与粒径分布的影响,分析其规律,建立了相应的关联式,可供聚合釜搅拌技术的改进和树脂质量的提高参考。     

氯乙烯本体预聚合动力学和成粒过程的研究

对氯乙烯(VC)本体预聚合动力学和成粒过程进行了研究。通过称重法测定了VC预聚合阶段的转化率,同时研究了搅拌转速、聚合温度和引发剂用量对聚合动力学的影响。采用LS-230Coulter激光粒度仪测定聚合过程PVC粒子的体均粒径及其分布,考察了搅拌转速、聚合温度和引发剂用量对临界转化率和临界粒径的影响。根据实验结果并结合低转化率下VC本体聚合的微观成粒机理,提出了VC本体预聚合的成粒过程。     

在氯乙烯悬浮聚合过程中的搅拌放大效应

我们根据所提出的实验数据证明了在氯乙烯悬浮聚合过程中聚合釜的搅拌强度和聚合釜的尺寸对产品树脂性能的影响。实验是在三台带搅拌的间歇釜中进行,釜的尺寸差距较宽(实验室规模、实验工厂规模和工业生产规模),反应器几何形状相似,三台釜的投料配方及操作步骤也都相同。 将主要搅拌参数如搅拌叶半径、宽度、速度联系起来用韦伯数表示,再求其对树脂性能的关系。用平均粒径对韦伯数作图时,发现三台釜的曲线都是U形曲线,这些曲线并不互相重叠而是各自展     

氯乙烯SET-DT悬浮聚合动力学和成粒过程的相互关系

以碘仿为引发剂、连二亚硫酸钠/碳酸氢钠为催化体系、聚乙烯醇(PVA)和/或纤维素衍生物(MC)为分散体系,进行氯乙烯单电子转移-蜕化链转移(SET-DT)活性自由基悬浮聚合,采用在线示踪气相色谱法和激光粒度分析系统研究分散剂种类和浓度、搅拌转速等对聚合动力学和单体液滴/聚合物颗粒粒径分布的影响。发现在相同搅拌转速下,以MC为分散剂的氯乙烯聚合速率最大,以PVA为分散剂时反应速率最小;分散剂种类固定时,聚合速率随分散剂浓度增大而增大。SET-DT悬浮聚合过程中,水相连二亚硫酸钠分解产生的自由基向单体液滴的扩散速率与液滴粒径分布和皮膜结构有关,因此聚合成粒过程影响聚合动力学。尽管不同条件下的聚合均经历液-液分散、液滴黏并、树脂颗粒稳定(转化率>30%)等成粒阶段,但各阶段的液滴/颗粒平均尺寸随分散体系和搅拌转速的变化而变化,引起聚合速率变化;采用MC为分散剂得到的PVC树脂皮膜少,有利于水相产生的自由基向单体相的扩散,聚合速率大。     

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.     

不同生产方法糊树脂复配对PVC增塑糊黏度及稳定性的影响

采用相近聚合度、不同生产方法的两种树脂进行复配,研究各复配比例下增塑糊黏度及稳定性。结果表明：当微悬浮法糊树脂1与MSP-3法糊树脂2的配比为80/20时,糊黏度大且稳定性最差;当树脂1/树脂2 =50/50时,糊黏度较低,稳定性最好。树脂1中引入树脂2（含量小于50 %）使得体系黏度上升,黏度稳定性也变差,糊树脂颗粒形貌的影响比粒度分布的影响更大;树脂2中引入树脂1（含量小于50 %）可降低其黏度和提高黏度的稳定性,主要是糊树脂颗粒形貌和粒度分布优化的原因。     

Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process

The heterogeneous polymerization of vinyl chloride monomer (VCM), with n‐butane as the reaction medium, was used to prepare poly(vinyl chloride) (PVC) resins. The particle features of the resulting resins and the particle formation mechanism of the polymerization process were investigated. The PVC resins prepared by the new polymerization process had a volume‐average particle size comparable to that of suspension PVC resins and a lower number‐average particle size. From scanning electron micrographs, it could be seen that the new PVC resins had a regular particle shape and a smooth surface with no obvious skin. They also had a high porosity. The new PVC resins were composed of individual and loosely aggregated primary particles. The diameter of the primary particles in the top layer of the grains was smaller than that of the primary particles in the center part of the grains. On the basis of the particle features of these PVC resins, a particle formation mechanism for the new polymerization process was proposed. PVC chains precipitate from a VCM/n‐butane mixed medium to form primary aggregates at a very low conversion, and the primary aggregates of the PVC chains aggregate to form primary particles, which further aggregate to form grains. The primary particles and grains grow by the capture of newly formed PVC chains and their primary aggregates and by polymerization occurring inside the aggregates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 954–958, 2003     

VDC-VC悬浮共聚树脂的颗粒特性研究

合成了偏氯乙烯(VDC)-氯乙烯(VC)悬浮共聚树脂，研究了聚合时间分散剂用量和搅拌器转速等对共聚树脂颗粒特性的影响。结果表明：树脂粒径随聚合时间延长而增大，并趋于定值；增加分散剂用量，粒径先减小后增大，当分散剂用量为0．12％时，平均粒径最小；平均粒径随搅拌器转速提高呈马鞍形变化，在130r／min时粒径最小，树脂颗粒形态规整。     

偏氯乙烯/丙烯腈悬浮共聚树脂的粒径及其分布

研究了分散剂浓度、搅拌转速、水油比等因素对偏氯乙烯／丙烯腈悬浮共聚树脂粒径及其分布的影响。结果表明,树脂颗粒的平均粒径随分散剂用量的增加而减少,并趋于平缓;平均粒径受搅拌转速的影响情况与分散剂用量有关,在实验的搅拌转速范围内,分散剂用量高于临界值（约略小于０．４％）时,平均粒径随搅拌转速增加而减小,在低于临界值时,平均粒径随转速增加呈马鞍形变化,平均粒径最低点对应的临界转速约为５００ｒ／ｍｉｎ;平均粒径随水油比的增加而减少,但影响较小。     

混合对丙烯腈连续水相沉淀共聚的影响 I.转速和挡板数的影响

以NaClO_3-Na_2SO_3为氧化还原引发剂,进行丙烯腈-丙烯酸甲酯-甲基烯丙基磺酸钠连续水相沉淀共聚。考察了2种桨型下搅拌速度和挡板数对转化率、分子量和共聚物颗粒形态的影响,结果表明,转数提高,则单体转化率升高,聚合物分子量降低,浆液含固率升高,聚合物平均粒径减小,粒径分布变窄,沉降值下降;挡板数增加,则共聚物颗粒形态变差,转化率与粒子表面积和体积有关,而与粒子数无关,符合高转化率下主要聚合场所是聚合物粒子的机理。     

The influence of additives on the primary particle nucleation and agglomeration in poly(vinyl-chloride)

The formation and agglomeration of PVC primary particles were studied in bulk polymerization experiments. In the absence of additives, the primary particles started to agglomerate at low conversions. The agglomeration conversion, as well as the size of the agglomerated particles, decreased when the agitation speed increased. At the highest speed tested, the agglomeration started already at 0.05 percent conversion. The primary particle size was about 0.16-0.18 μm, and seemed to be constant in the conversion interval studied (up to 5 percent). This indicated that the nucleation rate of primary particles was almost constant and that the growth rate of agglomerated particles was very low. The addition of sorbitan monolaurate produced a decrease in primary particle size. Polymeric additives such as PMMA, EVA, and PVAc stabilized primary particles against agglomeration but had no marked effect on the primary particle size. The monomer-soluble fraction of poly(vnyl alcohol-b-vinyl acetate) with high content acetate groups did not affect either the particle size or the agglomeration process.     

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