复合橡胶改性聚苯乙烯的结构与性能

研究了复合橡胶对高抗冲聚苯乙烯(HIPS)结构与性能的影响,并用透射电子显微镜对HIPS进行了表征。结果表明:低顺聚丁二烯橡胶(简称低顺橡胶)能增加HIPS橡胶相体积分数,使橡胶粒子形态分布更均匀;高顺聚丁二烯橡胶(简称高顺橡胶)有利于提高产品的韧性;低顺橡胶对HIPS弯曲强度和拉伸强度的增加贡献更大;采用高顺橡胶与低顺橡胶复合,能够协调HIPS的韧性、弯曲强度和拉伸强度。     

高抗冲聚苯乙烯的研制 Ⅲ.橡胶粒径分布及其对HIPS性能的影响

采用本体-悬浮法研究了高抗冲聚苯乙烯(HIPS)所用橡胶的结构及工艺条件对产品性能的影响。研究发现,随橡胶中乙烯结构含量的增加,HIPS橡胶接枝率增加;低顺胶HIPS橡胶相与PS相的相容性较差,高顺胶HIPS橡胶相与PS相的相容性好;从力学性能看,各种胶的HIPS拉伸性能相似,高顺胶的HIPS冲击性能最好,低顺线型胶次之,低顺星型胶较差。聚合过程中搅拌速度、橡胶用量及引发剂种类对HIPS的结构及性能也有一定影响。     

核壳改性剂增韧聚苯醚/聚苯乙烯共混物的形态结构及性能

采用乳液聚合方法合成了核壳比为50/50(聚丁二烯/聚苯乙烯,PB/PS),粒径分别为120 nm和350 nm的PB-g-PS接枝共聚物,而后将PB-g-PS弹性体与高抗冲聚苯乙烯(HIPS)同时作为改性剂增韧聚苯醚(PPO)/聚苯乙烯(PS)共混物,考察了基体组成(PPO/PS)和橡胶粒子尺寸对HIPS/PPO/PS/PB-g-PS共混物的力学性能及形态结构的影响。结果表明,随着基体中PPO含量的增加,共混物的冲击强度和拉伸屈服强度显著提高。HIPS中Salami结构橡胶粒子和亚微米尺寸橡胶粒子在PPO/PS基体中分散状态较好,协同增强了共混物的韧性;随着PB-gPS橡胶粒子尺寸的增加,共混物的冲击强度逐渐增加而拉伸屈服强度无明显变化,同时共混物的冲击断裂方式逐渐由脆性断裂向韧性断裂发生转变。     

影响高抗冲聚苯乙烯力学性能的因素

综述了影响高抗冲聚苯乙烯（HIPS）力学性能的各种因素，如苯乙烯均聚物的相对分子质量及其分布、橡胶接枝、橡胶粒子及其分布和橡胶相体积分数等。强调HIPS结构是影响其力学性能的直接因素，其他因素都是通过影响高分子结构来影响其力学性能的。     

高抗冲聚苯乙烯(HIPS)连续生产的模拟

根据热引发连续本体聚合生产高抗冲聚苯乙烯 (HIPS)的动力学机理 ,建立了苯乙烯 /顺丁二烯橡胶本体聚合过程的多釜串联 (CSTR)数学模型 ,并由两个不同品牌的实际工业生产数据对模型进行了验证。得到了各釜出口苯乙烯单体的转化率、HIPS的接枝效率、接枝率以及自由PS的重均分子量及其分布     

橡胶含量及加工条件对HIPS/PS/PB-g-PS共混物性能的影响

用乳液聚合以CHP-FeSO4为引发体系合成PB-g-PS接枝粉料,与商业高抗冲聚苯乙烯(HIPS)和聚苯乙烯(PS)共混制备HIPS/PS/PB-g-PS舍金.当HIPS的质量分数为10%,PB-g-PS的加入量为15%时体系发生脆韧转变.当HIPS质量分数为10%,橡胶加入量为15%时,体系的冲击强度随挤出机转数的增加而变大.扫描电镜(SEM)研究表明:挤出机转数低加工时剪切强度不够,体系的相容性不好导致脆性断裂.     

高光泽高抗冲聚苯乙烯的结构与性能

利用激光粒径分析仪、动态力学分析仪和气相色谱-液相质谱联用仪等分析了高光泽高抗冲聚苯乙烯(HIPS)和普通HIPS的结构和性能。结果表明:两个高光泽HIPS(HIPS A和HIPS B)试样在力学性能上的表现各有侧重。高光泽HIPS的溶胀指数与普通HIPS(HIPS C)相近,为11.0左右,表明三个试样的交联程度相近。相对于高顺式聚丁二烯橡胶改性的HIPS,高光泽HIPS中苯乙烯与橡胶的接枝点数量多,光泽度提高了约三倍,橡胶相平均粒径为1.0μm左右且分布较窄,凝胶质量分数大于22.0%,低相对分子质量组分的质量分数为2.1%～2.9%,但硬脂酸锌添加量大。HIPS A,HIPS B,HIPS C中的增塑剂含量逐渐增加。     

本体连续法制备高抗冲聚苯乙烯树脂引发体系的研究

利用平推流反应器和连续本体聚合方法,制备了高抗冲聚苯乙烯树脂(HIPS)。分别研究了热引发体系和自由基引发体系下,HIPS树脂制备过程中的橡胶相接枝反应和PS相的形成过程,以及对HIPS性能的影响。结果表明,对于热引发体系而言,橡胶相的接枝反应主要存在于第一反应器和第二反应器的4区,PS相的形成主要存在于第二反应器的5、6区和第三、第四反应器;对于自由基引发体系,橡胶相接枝反应和PS的聚合反应在低于热引发体系的温度下进行,接枝反应则主要发生于第一、第二反应器,PS相的形成主要在第三、第四反应器中进行。反应初期温度降低有利于橡胶相接枝反应,而反应后期温度升高则利于高摩尔质量PS的制备,自由基引发体系制备的HIPS性能更加优良。     

高抗冲聚苯乙烯的研究

本文报告了用顺丁橡胶(顺式含量>94%)增韧聚苯乙烯的研究。得到缺口冲击韧性达22.4公斤-厘米/厘米的高抗冲聚苯乙烯(HIPS)。并对HIPS的合成、HIPS的剖析、搅拌速率、橡胶含量、连续相分子量和大小粒径橡胶的共混与HIPS性能的关系作了叙述。     

高抗冲聚苯乙烯体系中橡胶相的粒径及其控制

在高抗冲聚苯乙烯(HIPS)体系中,橡胶相的粒径一般在0.5微米以上。若橡胶相的形态基本上保持圆形,并具有适当的交联度,则橡胶相的粒径对熔融指数和加工性能影响不大,但对抗冲强度和制件外观有较大的影响。在一般情况下,橡胶相的种类及数量、树脂的分子量及其分布都是确定的,因此抗冲性能则主要取决于橡胶相的粒径大小。     

Continuous Dosing of a Fast Initiator during Suspension Polymerization of Vinyl Chloride for Enhanced Productivity: Mathematical Modeling and Experimental Study

An adopted mathematical model was developed to reduce the batch time required for the suspension polymerization of vinyl chloride in order to improve the productivity by continuous dosage of a fast initiator during polymerization reaction. The model was accompanied by a particle swarm optimization (PSO) algorithm, so as to optimize the initiator dosage rate during the process for a certain conversion. A pilot scale reactor was employed to verify the mathematical model predictions. This showed that the model predictions are in very good agreement with the experimental data. A proper initiator dosage trajectory during the course of the reaction was obtained in such a way that the reaction rate over the course of polymerization was constant and corresponded to the maximum rate in the conventional case (non-continuous addition of a mild initiator). The maximum reduction in reaction time relative to conventional polymerization for the predefined conversion was 53%. Analyzing the molecular characteristics of the samples showed that the molecular characteristics of the final poly(vinyl chloride) (PVC) product remained relatively unchanged under an optimum initiator dosage trajectory compared with the conventional process.     

Metal-containing initiator systems

Summary The polymerization of vinyl monomers with the initiator systems of ferrocene and acid anhydrides were investigated. The initiator activity for radical polymerization of methyl methacrylate (MMA) was higher than that for styrene (St). However, isobutyl vinyl ether was not polymerized. The rate of polymerization of MMA with ferrocene/benzoic anhydride system was in proportional to the square root concentrations of both compounds of the initiator system, indicating the mechanism of radical polymerization. When an alternating copolymer of ethylene with maleic anhydride was used as an acid anhydride, a graft copolymer, which was soluble in dimethylformamide and tetrahydrofuran, was produced from radical polymerization of MMA.     

Radical polymerization of acrylonitrile initiated by α-picolinium p-chlorophenacylid

The radical polymerization of acrylonitrile (AN) with α-picolinium p-chlorophenacylid (α-PCPY) as initiator using carbon tetrachloride as inert solvent was investigated at 50°C. The polymerization follows ideal kinetics: the exponent values calculated for the initiator and monomer were found to be 0.5 and unity, respectively. A free radical mechanism with bimolecular termination was confirmed by the inhibiting effect of hydroquinone, a radical quencher. The rate of polymerization was a direct function of initiator (α-PCPY) concentraction, monomer (AN) concentration and temperature. The overall activation energy calculated was 56 kJ/mol. The polymerization was favoured by polar solvents and retarded by non-polar solvents.     

丙烯酸丁酯细乳液单电子转移-蜕化链转移聚合反应

单电子转移-蜕化链转移(SET-DT)聚合是一种单体适用性广、对聚合环境要求不苛刻的活性自由基聚合方法。以Na_2S_2O_4为催化剂,CHI3为引发剂,采用水相细乳液聚合法进行丙烯酸丁酯(BA)的SET-DT活性自由基聚合,考察了聚合温度、引发剂/催化剂浓度、催化剂滴加方式和乳化剂浓度对聚合动力学、聚丙烯酸丁酯(PBA)数均分子量和分子量分布的影响。结果表明,细乳液聚合速率明显大于悬浮聚合,可在较低温度(30℃以下)、较低引发剂和催化剂浓度(BA,CHI_3和Na_2S_2O_4的初始摩尔浓度比为1 600:1:8)下实现BA的快速聚合;通过聚合过程滴加Na_2S_2O_4催化剂和增加十二烷基硫酸钠主乳化剂浓度,可提高聚合速率;采用低引发剂浓度和催化剂逐步滴加聚合得到的PBA的平均分子量较大,分子量分布较窄。     

氯乙烯悬浮(本体)聚合用过氧化物引发剂

介绍了氯乙烯(VC)悬浮(本体)聚合常用过氧化引发剂的合成方法，着重阐述引发剂与聚合动力学的关系以及聚合动力学的检测方法。研究了单一和复合引发剂条件下的VC聚合动力学，为优化引发剂体系、缩短聚合时间、提高聚合釜的生产能力提供理论基础。     

Aqueous polymerization of ethyl acrylate initiated by ceric ion‐reducing agent systems in nitric acid medium

Kinetic study of aqueous polymerization of ethyl acrylate (EA) was carried out at 30 °C in dilute nitric acid medium by employing ammonium ceric nitrate (ACN)–methyl cellosolve (MC) and ACN–ethyl cellosolve (EC) as redox initiator systems. The ceric ion consumption was found to be first order with respect to ceric ion concentration with both initiator systems. The formation of complexes between Ce(IV) and reducing agents (RA) was observed. The order with respect to Ce(IV), reducing agents and monomer was evaluated for aqueous polymerization of EA by Ce(IV)–MC and Ce(IV)–EC redox initiator systems. The overall activation energy, E_overall, for aqueous polymerization of EA was evaluated in the temperature region of 27–40 °C with both initiator systems. A kinetic mechanism for aqueous polymerization of EA initiated by redox initiator systems is presented. © 2001 Society of Chemical Industry     

非腈复合引发剂用于乙酸乙烯溶液聚合

以生物乙烯法生产的乙酸乙烯为单体、过氧化月桂酰-十二烷基二甲基叔胺为非腈复合引发剂、甲醇为溶剂进行溶液聚合反应的研究。实验考察了反应温度、反应时间、甲醇用量、引发剂用量对反应产物聚合率和聚合度的影响,采用正交试验优化了乙酸乙烯溶液聚合的反应条件,确定反应因素对聚合率和聚合度影响的相对大小。结果表明,最优的乙酸乙烯溶液聚合条件为:反应温度65℃,反应时间3h,甲醇用量10%,引发剂用量0.010%,获得聚乙烯醇产品的聚合度为3776,聚合率为45.29%。直观分析确定影响聚合率的因素主次顺序为引发剂用量> 反应时间> 甲醇用量> 反应温度;影响聚合度的因素主次顺序为甲醇用量 >引发剂用量 >反应温度 >反应时间。     

Surface grafting of polyacrylamide from polyethylene‐based copolymer film

Atom transfer radical polymerization (ATRP) was used to grow polyacrylamide from the surface of ethylene–acrylic acid copolymer (EAA) film. The surface functionalization constituted initiator immobilization and surface graft polymerization. All reaction steps were conducted at 24 ± 3°C; polymerization was done in aqueous solution. For initiator immobilization, the carboxylic acid groups on EAA film were converted to acid chloride groups; further reaction with ethanolamines gave hydroxyl groups onto which 2‐bromoisobutyryl bromide initiator was attached. ATR‐FTIR data indicated that 1.64 ± 0.09 times higher initiator density was achieved by using diethanolamine, relative to ethanolamine. Acrylamide monomer was polymerized from the initiator by ATRP to yield nondistorted, transparent films with polymerization times of up to 1 h. For films prepared using diethanolamine, 1 h polymerization time reduced the static water contact angle by more than 50°, significantly increasing the hydrophilicity of the film surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1589–1595, 2004     

苯乙烯-甲基丙烯酸甲酯悬浮-乳液耦合聚合动力学

采用苯乙烯(St)悬浮聚合过程滴加甲基丙烯酸甲酯(MMA)乳液聚合组分,进行悬浮-乳液耦合聚合(SECP), 制备大粒径聚苯乙烯-聚甲基丙烯酸甲酯(PS-PMMA)复合粒子.采用¹H NMR分析方法,讨论了SECP动力学特征.St的SECP聚合速率和转化率与悬浮聚合一致;MMA聚合速率决定于乳胶粒子聚合速度和凝并在悬浮粒子表面的速度,聚合速率比常规乳液聚合速率低.由于凝并在悬浮粒子表面的PMMA乳胶粒子不再有乳液聚合特征,MMA在SECP中转化率低于同条件常规乳液聚合.分别得到乳化剂和引发剂浓度与SECP和普通乳液聚合恒速段聚合速率的关系.     

氯乙烯/异丁基乙烯基醚乳液共聚物的合成

以(NH4)2S2O8／Na2SO3／CuSO4为氧化-还原引发体系、十二烷基硫酸钠(SDS)为乳化剂，采用间歇乳液聚合合成氯乙烯／异丁基乙烯基醚(VC／IBVE)共聚物。结果表明，当投料单体中IBVE质量分数增加时,相同聚合时间的聚合转化率和共聚物特性粘度明显降低。当转化率小于70％时，共聚物平均组成变化不大；聚合温度增加使聚合速率增加，但共聚物特性粘度减小；SDS浓度对聚合速率和共聚物特性粘度的影响很小；随引发体系浓度增加．聚合速率增加，共聚物特性粘度变化不大。