高转化率E－SBR1500生胶和硫化胶的性能研究

对用高活性引发体系在较短聚合周期（９—１１ｈ）内合成的高转化率（７％）Ｅ－ＳＢＲ１５００生胶的门尼粘度、凝胶含量、结合苯乙烯含量、分子量分布、组成分布和微观结构等基本特性参数和硫化胶的物性进行了试验研究。结果表明：生胶的各项特性指标和硫化胶物性均达到了６０％转化率的我国吉化和日本ＪＳＲ胶样的实测值水平。     

高转化率E-SBR1500生胶和硫化胶的性能研究

对用高活性引发体系在较短聚合周期（９－１１ｈ）内合成的高转化率（７０％）Ｅ－ＳＢＲ１５００生胶的门尼粘度、凝胶含量，结合苯乙烯含量，分子量分布，组成分布和微观结构等基本特性参数和硫化胶的物性进行了试验研究，结果表明，生胶的各项特性指标和硫化物性均达到了６０％转化率的我国吉化和日本ＪＳＲ胶样的实验值水平。     

乳聚丁苯橡胶的分子量分布和凝胶

本文通过实验讨论了SBR生产中,转化率、硫醇加入量及加入方式对产物分子量分布的影响,并分析了门尼粘度与分子量分布间的关系。SBR中除少量大凝胶外,还含有15～25％的微凝胶,由大分子缠结或轻度交联形成,在外力作用下易断裂。这些微凝胶在SBR的分子量分布图中表现为高分子级分部位的肩峰。     

单体转化率对乳液丁苯基本特性和微观结构的影响规律

本文研究了单体转化率对乳液丁苯门尼粘度和特性粘度、凝胶含量、结合苯乙烯合量、玻璃化温度、胶乳稳定性、分子量及分布和微观结构的影响规律．为进一步提高丁苯聚合转化率、保证橡胶质量提供了有力依据。     

苯乙烯－低顺丁橡胶高温高转化率接枝共聚动力学

本文在玻璃封管中进行了高温（１１０～１７０℃）高转化率（＞８０％）苯乙烯－低顺丁橡胶接枝共聚，研究了聚合温度、引发剂浓度、转化率等因素对聚合速率、聚合物分子量及分子量分布的影响。发现在较低温度（１１０℃）下存在凝胶效应，在较高温度下则无凝胶效应；加入橡胶使苯乙烯聚合速率和分子量降低，橡胶起着缓聚和链转移作用。     

调节剂增量加入对SBR1502性能的影响

研究了增量加入调节剂ｔ－Ｃ１２ｈ２５ＳＨ对单体转化率为７０％的ＳＢＲ１５０２分子参数的调节作用。结果表明，当增量：初加量为２５：７５（质量比），增量加入时的转化率为３０％－４５％时，聚合物的分子量，分子量分布，门尼粘度，凝胶含量均可行进行有效控制；所得产品的物理机械性能达到或超过了ＪＳＲ１５０２及Ｎｉｐｏｌ１５０２的指标。     

2,4-二苯基-4-甲基-1-戊烯在丙烯酸酯共聚乳液中的应用研究

比较了分子量调节剂αMSD(2,4-二苯基-4-甲基-1-戊烯)与NDDM(正十二硫醇)对MMA-BA共聚乳液聚合物的分子量及其分布、聚合速率、乳液固含量、单体转化率、粒径、黏度、凝胶率等因素的影响,并对αMSD的调节机理进行了分析。研究结果表明:较低αMSD用量即可降低聚合物分子量,使分子量分布变窄,与正十二硫醇的作用结果差别不大;αMSD会引起丙烯酸酯乳液聚合速率的下降,用量超过1%后会导致乳液固含量和单体转化率的明显下降,乳液粒径分布会变宽,乳液黏度也有所增加,但体系凝胶率始终较低;而NDDM则会引起产物乳液粒径小幅增加,凝胶率升高;通过红外分析确定了αMSD按Yasummasa式不可逆加成断裂链转移反应而起调节作用。     

聚合转化率对硫调型氯丁胶结构与性能的影响

研究了硫调型氯丁橡胶乳液聚合中转化率对产晶结构与性能的影响.结果表明,随单体转化率的提高,聚合物的凝胶量及其交联密度增大,致使断链速度减慢,所得断链胶的门尼粘度上升,残存凝胶量增加,分子支化程度增大,分子量分布变宽,焦烧时间缩短。而相应硫化胶的拉伸强度、撕裂强度、冲击弹性和硬度等提高,扯断伸长率和永久变形下降。这些变化一般在转化率为80——85％时有明显转折.综合考虑产量与质量,聚合转化率控制在82±2％较为适宜。     

影响乳聚丁苯橡胶门尼粘度的因素

本文论述了乳聚丁苯橡胶合成过程中,分子量调节剂TDM的加入方式,单体总转化率以及聚合速率等因素对生胶门尼粘度(ML_(1+4)~(100℃)的影响,同时对分子量分布、凝胶含量、特性粘度与门尼粘度的关系也做了研究。     

聚乙二醇/丙烯酸共聚水凝胶的制备及pH敏感性研究

采用热引发反应制备了聚乙二醇(PEG)／丙烯酸(AAc)共聚物水凝胶,研究了PEG与AAc比例、交联剂、引发剂含量及反应时间等因素对反应转化率和不同pH缓冲液对水凝胶溶胀比的影响。结果发现PEG／AAc配比为(3：7)～(4：6)之间时,凝胶转化率较大;引发剂、交联剂含量分别为PEG和AAc总含量的0．5％和0．4％时,反应时间为5h,凝胶转化率较高;PEG：AAc为6：4时,水凝胶具有较明显的pH敏感性。     

提高转化率对乳聚丁苯橡胶性能的影响

以吉林石化公司有机合成厂的乳聚丁苯橡胶(SBR)生产配方为标准配方,研究了聚合反应时间对转化率的影响,分析了提高转化率对SBR的生胶门尼黏度、结合苯乙烯含量、凝胶含量、相对分子质量及其分布、胶乳黏度等基本性能的影响。结果表明,在标准配方条件下,延长聚合反应时间,转化率可以达到70%。转化率为70%时所得SBR与转化率为62%时所得SBR相比,前者的生胶凝胶含量和胶乳黏度均增大了1倍,数均相对分子质量、重均相对分子质量和Z均相对分子质量均高于后者,相对分子质量分布变宽,且前者的生胶结合苯乙烯含量能够达到产品标准,而生胶门尼黏度和在50 m in时的300%定伸应力偏高于产品优级品要求。     

高转化率乳聚丁苯橡胶聚合过程中乳液相对分子质量分布与粒径分布考察

采用中石油吉化分公司乳聚丁苯橡胶高转化率大生产配方,考察了实验室聚合反应釜聚合反应单体转化率随反应时间的变化,采用激光粒度分析仪和凝胶渗透色谱仪测定了聚合反应不同单体转化率的胶乳的粒径分布与分子质量分布,结果表明：胶乳粒径呈正态分布,粒径主要集中分布在0.1μm附近,胶乳的平均粒径随反应时间的延长逐渐增大,但是增加的幅度越来越小;聚合反应时间在11 h前（即转化率小于72%）,胶乳的重均分子质量、Z均分子质量一直增大,而数均分子质量变化无明显规律;而分子质量分布宽度指数随反应的进行变小,表明调整的高转化率配方合成的丁苯橡胶可有效改善聚合生成的胶乳粒径分布。     

国产顺丁橡胶BR 9000 性能对比测试

对国内8 家合成橡胶厂生产的顺丁橡胶BR 9000 进行了相对分子质量及其分布、微观结构、生胶性能、硫化特性和硫化胶性能的对比测试。结果表明,国产BR 9000 与国外同类产品相比其数均分子量偏低,重均分子量偏高,分子量分布较宽。国产BR 9000 在微观结构、灰分、挥发分及凝胶含量等方面相当,但A 厂的挥发分含量偏高,H 厂的凝胶含量较大; 硫化速率基本相同,硫化胶的定伸应力、拉伸强度和扯断伸长率处于同一水平; 国产BR 9000 的性能指标均能满足优等品的要求。     

Preparation and characterization of polyacrylate/polymerized rosin composite emulsions by seeded semicontinuous emulsion polymerization

Polyacrylate/polymerized rosin composite emulsions were prepared by seeded semicontinuous emulsion polymerization of acrylate monomers in which polymerized rosin was dissolved. The effects of polymerized rosin content on the polymerization stability, monomer conversion, polymer structure, and adhesive properties were studied. Polyacrylate/polymerized rosin composites were characterized by gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogracvimetry (TG). The results showed that with an increase of polymerized rosin content from 0 to 6 wt %, gel fraction and sol molecular weight decreased obviously but monomer conversion was basically unchanged. In contrast, with a further increase of polymerized rosin content, the decreasing rates of gel fraction, and sol molecular weight were slowed down. Meanwhile, monomer conversion decreased remarkably. Moreover, interface failure changed into cohesive failure after the addition of polymerized rosin, and the peel adhesion and shear resistance of composite latex films declined with the increase of polymerized rosin content. Thermal analysis showed that polymerized rosin and polyacrylate were compatible and the composite latex films had good thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高转化率配方乳聚丁苯橡胶聚合过程中间产物性能考察

采用中国石油吉林石化公司乳聚丁苯橡胶高转化率大生产配方,考察了实验室聚合反应釜聚合反应单体转化率随反应时间的变化,测定了生胶的结合苯乙烯含量、有机酸和皂含量、门尼粘度等性质,结果表明：反应10 h,转化率为70%左右时生胶的各项性质均达到标准GB/T 8655—2006中规定的优等品指标要求;当反应12 h,转化率达到75%时,生胶的结合苯乙烯含量和门尼粘度不符合要求。     

Influence of gel and molecular weight on the properties of natural rubber

The influence of gel and molecular weight on the properties of natural rubber has been described. Crystallization, stress relaxation and orientation properties of different samples have been studied. Samples having different gel contents but similar molecular weights and samples having the same gel content with varying molecular weights have been prepared by extracting whole natural rubber. The gel content was varied from 1.5 to 29% and molecular weight from 1 × 10⁵ to 9.9 × 10⁵ g mol⁻¹. The gels reduce the overall crystallinity measured by differential scanning calorimetric experiments after freezing the samples for different time periods at −15°C. They also have a stiffening effect on the tensile relaxation modulus and decrease the rate of relaxation significantly. Birefringence, which measures the orientation and stress-induced crystallization, increases with time at high elongation for samples containing gels. At lower elongation, however, the birefringence of unvulcanized samples decreases with time. This decrease is less for gel samples. Natural rubbers of high molecular weight behave similarly in the above properties when compared to low molecular weight samples. The effect of gel is more predominant than that of molecular weight.     

镍系顺丁橡胶聚合凝胶原因分析及预防措施

凝胶含量是顺丁橡胶的重要质量指标,它直接影响到生产反应、产品的内在质量和加工性能。降低凝胶含量,一直是顺丁橡胶技术攻关的目标。通过多年来的研究,结合生产实际,叙述了凝胶对顺丁橡胶生产的影响,重点分析了凝胶生成的原因,提出了如何在生产过程中控制凝胶生成的方法。使产品具备玻璃化温度低,压缩变形小,分子量容易控制,分子量分布也较宽,加工性能好等特点。     

Synthesis of Polyelectrolyte and Studies of its Conductivity Changes with Respect to Molecular Weight

Aqueous solutions of acrylamide monomer were irradiated by γ-rays using a Co-60 source to synthesize polyacrylamide of different molecular weight (M_w). Solubility tests together with ultraviolet and infrared spectroscopic studies were performed for examining the irradiated samples to ensure that the prepared products were gradually converted from monomer to polymer (polyacrylamide), depending on the radiation dose. Various physico-chemical properties like polymer conversion, gel content, viscosity, and molecular weight of the products were determined. The conversion of polymer from monomer is initiated at a dose of 0.06 kGy and completed at about 0.14 kGy. The gel point, which indicates a dose for the onset of a network polymer structure, is identified to be 0.15 kGy providing valuable information about γ-ray synthesis of polyacrylamides. Viscosity and molecular weight are found to increase with radiation dose. Since polyacrylamides exhibit polyelectrolytic behavior in aqueous solutions, studies on conductivity changes of polyelectrolytes with respect to M_w, which is the main issue of this investigation, also were performed. The equivalent conductance of polyelectrolyte solutions was found to decrease with the molecular weight of the synthesized polymer. This change of conducting property of the prepared samples is explained based on the theory of polyelectrolyte solutions.