Properties of modified polyacrylonitrile membranes prepared by copolymerization with hydrophilic monomers for water–ethanol mixture separation

A new kind of terpolymer membrane was employed to separate a permselective water–alcohol mixture. This membrane was prepared via the copolymerization of acrylonitrile, sodium salt styrene sulfonic acid (SStSA), and hydroxyethyl methacrylate in dimethylsulfoxide with azobisisobutyronitrile as an initiator. The reaction mechanism, resultant structure, and polymer composition were confirmed by IR and elemental analysis. The effects of the feed composition on the polymer composition, mechanical properties, thermal properties, and degree of swelling were investigated. It was found that water permeated through the membrane preferentially in a water/alcohol system. The flux increased with the increase of SStSA, but the separation factor decreased drastically with higher SStSA. For a 50 wt % water–ethanol mixture, a flux of 0.65 kg/m² h and a separation factor of 212 were obtained at 30°C when the membrane containing the highest SStSA content was used. The capacities of the metal ions absorbed by the membranes were investigated in the study. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 244–250, 2003     

Semi-continuous emulsion copolymerization of butyl methacrylate with polymerizable anionic surfactants

Two polymerizable anionic surfactants sodium 4-(ω-acryloyloxyalkyl)oxy benzene sulfonate (SABS-n, n=8 or 10) have been successfully used in the semi-continuous emulsion copolymerization with butyl methacrylate (BMA). After generating seeding particles in an emulsion consisting SABS-8 or SABS-10 and small amount of BMA using a redox initiator ammonium persulfate (APS)/tetramethylethylenediamine (TMEDA) at room temperature, most of BMA was added drop-wise to the polymerizing emulsion system during a period of 4-8 h. These emulsion copolymerizations produced nanosized latexes with high polymer/surfactant weight ratios up to about 12/1 and nearly monodisperse particles ranging from 18 to 33 nm in diameter. X-ray photoelectron spectroscopy results showed that SABS-n was significantly enriched on the surface of latex particles. The effects of concentrations of SABS-n, BMA, and APS/TMEDA and the latex characteristics during the continuous addition of monomer were studied. A possible polymerization mechanism was proposed.     

Polymerization Catalysis in Liquid Propylene: High Activities and Molecular Weights in Propylene/CO Copolymerization Reactions

Summary: The dicationic [(dppp)Pd(NCCH₃)₂](BF₄)₂ catalyst (dppp = 1,3‐bis(diphenylphosphino)propane) was applied in a liquid monomer, two phase process for the CO/propene copolymerization reaction. For the first time it was possible to synthesize propene/CO copolymers with an activity up to 7 500 g/(mol · h) and molecular weights of 500 000 g/mol. Activities up to 40 000 g/(mol · h) could be obtained with the use of the unsymmetric catalyst [(CF₃‐dppp)Pd(NCCH₃)](BF₄)₂ (CF₃‐dppp = 1‐diphenylphosphino‐3‐bis[3,5‐di(trifluormethyl)phenyl]phosphinopropane) in homogeneous liquid propene solution.

Granules found after copolymerization.     

聚合松香HEMA酯化物与苯乙烯的共聚研究

以聚合松香(PR)与甲基丙烯酸-β-羟乙酯(HEMA)的酯化物(PRH)为单体,采用自由基溶液聚合方法制备了PRH与苯乙烯(St)的共聚物(PRHS)。探讨了单体比例、反应温度、引发剂用量和反应时间对共聚反应的影响。用红外光谱、热重分析和差示扫描量热分析对产物的结构、热稳定性和玻璃化转变温度进行了测试表征。结果表明:成功合成了酯化物PRH与St的共聚物PRHS;共聚物的热稳定性高于酯化物,苯乙烯用量越多,共聚物热稳定性和玻璃化转变温度越高;PRH与St共聚较佳的反应条件为:mPRH∶mSt=1∶2;反应温度为110℃;m(引发剂)∶m(单体)=1%;反应时间为8 h,在此条件下,产率达70.14%。     

蓖麻油-马来酸酐-苯乙烯双功能润滑油添加剂的合成

传统石油基润滑油添加剂对环境的不利影响,使可生物降解的植物油基润滑油添加剂成为研究热点。以蓖麻油(CO)、马来酸酐(MAH)、苯乙烯(ST)为原料,偶氮二异丁腈(AIBN)为引发剂,甲苯为溶剂,合成了蓖麻油-马来酸酐-苯乙烯共聚物(PCMAS)。通过红外光谱(FT-IR)、核磁共振氢谱(¹H NMR)表征了蓖麻油-马来酸酐-苯乙烯共聚物的结构,采用凝胶渗透色谱(GPC)测定了聚合物的相对分子质量及其多分散性指数,采用热重分析研究了聚合物的热稳定性,并对聚合物作为润滑油降凝剂和黏度指数改进剂的性能进行了评价。结果表明：当单体质量比m(CO)∶m(MAH)∶m(ST)=1.0∶0.2∶1.2、引发剂AIBN含量占总单体的0.5%(质量分数)、反应时间4 h、反应温度90℃时,共聚物收率为68.39%,其数均相对分子质量为0.348×10⁵,多分散性指数为4.77。将蓖麻油-马来酸酐-苯乙烯共聚物添加到润滑油馏分(350～395℃)中,可降低润滑油的凝点,并提高其黏度指数。蓖麻油-马来酸酐-苯乙烯共聚物可作为一种具有降凝增黏双重功能的润滑油添加剂。     

二甲氨基链中多官能化溶聚丁苯橡胶的合成

采用负离子溶液聚合法,以仲丁基锂为引发剂、环己烷为溶剂、四氢呋喃为结构调节剂,以及1,1-双（4-二甲基氨基苯基）乙烯为官能化共聚单体与丁二烯和苯乙烯进行活性负离子共聚合,制备了二甲氨基链中多官能化丁二烯-苯乙烯共聚物,考察了聚合温度和结构调节剂用量对聚合动力学和聚合物微观结构的影响。结果表明,共聚物链中二甲氨基官能团数量可通过调整聚合温度和结构调节剂用量进行准确控制,随聚合温度升高和四氢呋喃用量的增加,单体的总反应速率和转化率都逐渐增大;聚合物中1,2-结构的含量随结构调节剂用量的增加而逐渐增大,随聚合温度升高而逐渐减小。求得聚合温度为50 ℃时丁二烯和苯乙烯单体的平均竞聚率为69.67。     

半芳香族聚酰胺PA6T及其PTFE复合材料的摩擦磨损性能研究

对3种不同共聚结构的聚对苯二甲酰己二胺（PA6T）树脂——聚对苯二甲酰己二胺/己内酰胺（1132）、聚对苯二甲酰己二胺/己二酰己二胺（M21）和聚对苯二甲酰己二胺/己二酰己二胺（1252）以及其聚四氟乙烯（PTFE）复合材料在干摩擦条件下的摩擦磨损性能进行了研究,并使用扫描电子显微镜（SEM）对试样的磨损面进行了分析。结果表明,1252的摩擦磨损性能最好,M21次之,1132最差;PTFE的加入提高了3种树脂的摩擦磨损性能,其中对1252的摩擦磨损性能改善最大,当PTFE含量为30份（质量份,下同）时,其摩擦因数和磨损率分别降低到了0.16和1.00×10^-6;磨损机理方面,1132的磨损方式主要表现为粘着磨损和疲劳磨损,而M21和1252的主要磨损方式表现为磨粒磨损;随着PTFE含量的增加,复合材料的主要磨损方式均转变为粘着磨损。     

铸造用动物胶粘结剂的接枝共聚工艺研究

介绍了铸造用接枝改性动物胶粘结剂的国内外发展状况,在分析铸造用动物胶粘结剂的接枝共聚原理的基础上,系统试验了乳化剂用量及乳化时间、引发剂加入量、反应温度与反应时间、交联剂加入量、丙烯酸甲酯加入量等因素对动物胶性能的影响,并确定了最佳接枝改性工艺。     

Kinetics of styrene emulsion polymerization with a stable monomer radical

We have analyzed the electrical conductivity of a linear high charge density polyelectrolyte aqueous solution, finding that the counterion association order follows the same pattern as that described for a cyclic monomeric polyelectrolyte, i.e. NO > Br^? > Cl^? > F^?. However, these counterions interact in a very different manner with this polyion, making Eisenberg's relationship inapplicable in this system. Consequently, an alternative method is proposed for treating data.     

PS-b-PEA嵌段共聚物的合成与表征

采用“活性”自由基聚合的方法合成了不同分子量的苯乙烯和甲基丙烯酸乙酯[polystyrene-block-poly(ethyl methacrylate),PS-b-PEA]嵌段共聚物。并用凝胶渗透色谱(GPC)和红外光谱(FTIR)对所合成的共聚物进行了表征,实验结果显示:在4-羟基-2,2,6,6-四甲基哌啶-1-氧化物自由基(HTEMPO.)和偶氮二异丁腈(AIBN)存在下,苯乙烯聚合反应所得到的聚苯乙烯分子量分布在1.18~1.2范围,分子量随聚合时间的延长而增大(7 200~69 300 g/mol);将该聚苯乙烯溶于甲基丙烯酸乙酯,在(130±2)℃时可以重新引发甲基丙烯酸乙酯的聚合反应,且甲基丙烯酸乙酯的聚合反应具有“活性”聚合的特征,共聚物的数均分子量及分布分别在57 800~107 800 g/mol和1.22~1.26范围,共聚物由FTIR表征显示:在聚苯乙烯接上聚甲基丙烯酸乙酯后,在1 158 cm-1及1 727 cm-1出现其甲基丙烯酸乙酯的特征吸收峰,说明共聚物为嵌段共聚物。