影响苯乙烯-异戊二烯-丁二烯乳液聚合体系反应速率的因素

通过乳液聚合制备了苯乙烯-异戊二烯-丁二烯三元共聚物,研究了影响其聚合速率的因素。结果表明,随着聚合温度的升高和乳化剂、引发剂及异戊二烯用量的增加,聚合速率均明显加快;调节剂用量的变化对聚合速率基本没有影响。     

丙烯腈-丁二烯-异戊二烯三元共聚物的合成

采用乳液聚合法于5℃合成了丙烯腈-丁二烯-异戊二烯三元共聚物(NBIR)。考察了单体配比、引发剂、乳化剂及相对分子质量调节剂用量对乳液聚合反应速率的影响,并通过傅里叶变换红外光谱、核磁共振氢谱与核磁共振碳谱对NBIR的组成及微观结构进行了表征。结果表明,随着乳化剂、引发剂用量的增加,聚合反应速率均增大;单体配比、相对分子质量调节剂对聚合反应速率无明显影响。固定总单体用量为100份、丙烯腈用量为33份,当丁二烯/异戊二烯(质量比)为50.0/17.0、33.5/33.5、17.0/50.0时,所得NBIR的结合丙烯腈质量分数均为33.3%左右,结合异戊二烯质量分数从19.7%增加到51.6%,其结合量均大于单体投料量;而结合丁二烯质量分数从47.2%下降到15.1%,其结合量均小于单体投料量。改变单体配比对NBIR聚丁二烯链段的1,2-结构含量和聚异戊二烯链段的3,4-结构含量均无明显影响。     

三元共聚物的聚合物组成影响因素研究

通过在丁苯乳液聚合过程中加入第三单体异戊二烯得到苯乙烯-异戊二烯-丁二烯三元共聚物,并通过改变实验条件研究了聚合转化率、聚合温度、引发剂用量、调节剂用量和单体配比等因素对聚合物组成的影响。结果表明,聚合时各单体投入量是影响聚合物组成的主要因素;其次,转化率的升高和聚合温度的升高会导致聚苯乙烯含量增加和聚异戊二烯含量减少。     

以双四氢糠丙烷为极性调节剂的苯乙烯-异戊二烯-丁二烯三元共聚动力学(英文)

以正丁基锂为引发剂,双四氢糠丙烷为极性调节剂,己烷/环己烷混合溶剂为溶剂,采用负离子聚合法进行苯乙烯-异戊二烯-丁二烯集成橡胶的三元共聚合,研究了反应温度和调节剂用量对苯乙烯、异戊二烯、丁二烯3种单体聚合反应动力学的影响。结果表明,随着温度升高及双四氢糠丙烷用量的增加,各单体的表观反应速率逐渐增加;随着双四氢糠丙烷用量的增加,表观增长反应活化能和频率因子逐渐减小;在同一条件下,单体的表观增长反应速率常数由大到小依次为丁二烯、苯乙烯和异戊二烯。     

苯乙烯-丙烯腈-马来酸酐三元共聚物的合成及其在PC/ABS中的应用

采用本体聚合的方法,以苯乙烯、丙烯腈、马来酸酐为反应单体,加入引发剂、链转移剂合成了苯乙烯-丙烯腈-马来酸酐(SAM)三元共聚物.研究了引发剂种类、用量及链转移剂用量对三元共聚物摩尔质量的影响,寻求最优的合成条件;并以自制的SAM来增容聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯(ABS)共混物,探讨了SAM对共混物性能的影响.通过红外(FTIR)、核磁(1H-NMR)、差示扫描量热仪(DSC)对三元聚合物结构进行了分析.研究表明:引发剂偶氮二异丁腈(AIBN)效果优于过氧化苯甲酰(BPO),苯乙烯、丙烯腈、马来酸酐物质的量之比为60:38:2,链转移剂十二硫醇(TDM)和引发剂偶氮二异丁腈(AIBN)的用量均为单体总质量的0.1%时,可获得摩尔质量为80 000g/mol左右的三元共聚物SAM;SAM对PC/ABS共混物起到了增容作用.     

以双四氢糠丙烷为极性调节剂的苯乙烯/异戊二烯/丁二烯三元共聚动力学

以正丁基锂(n-BuLi)为引发剂,双四氢糠丙烷(DTHFP)为极性调节剂,环己烷为溶剂,采用负离子聚合法合成了线型苯乙烯(St)-异戊二烯(Ip)-丁二烯(Bd)三元共聚物,考察了三元共聚合总反应速率的影响因素,研究了三元共聚合反应动力学,并与传统极性调节剂四氢呋喃(THF)体系进行了比较。结果表明,在单体质量分数为12%,St/Ip/Bd(质量比)为20/40/40,设计单臂相对分子质量为10×104的条件下,随着聚合反应温度的升高或DTHFP/n-BuLi(摩尔比)的增加,总转化率和总反应速率逐渐增大,聚合反应的假一级表观增长反应速率常数增大;表观增长反应活化能和频率因子均随DTHFP/n-BuLi值的增加而减小;DTHFP在用量较小的情况下与较大THF用量的效果相当,促进聚合反应速率的能力明显高于THF。     

高温本体聚合合成ACS树脂的接枝率研究

研究了聚合条件、配方组成及氯化聚乙烯(CPE)的氯化度对高温本体聚合合成丙烯腈(AN) CPE苯乙烯(St)接枝共聚物（ACS）树脂接枝率的影响。结果表明,本体聚合合成ACS树脂过程中接枝反应主要发生在聚合转化率低于50 %的低转化率阶段;反应温度、引发剂及链转移剂用量是影响本体聚合合成ACS接枝率的主要因素;提高聚合反应温度、增加引发剂和链转移剂浓度均会导致接枝率显著下降;St/AN的质量比、CPE橡胶的含量及氯化度对接枝率的影响较小。     

含锡有机锂引发的苯乙烯-异戊二烯-丁二烯共聚合

以含锡有机锂为引发剂、四氢呋喃（THF）为极性调节剂进行了苯乙烯异戊二烯-丁二烯集成橡胶（SIBR）的负离子三元共聚合,研究了温度、调节剂用量及引发剂浓度对其反应动力学的影响及SIBR的性能。结果表明,随着温度升高及THF用量和引发剂浓度的增加,各单体的表观反应速率逐渐增加;随着THF用量的增加,增长反应的表观活化能和频率因子逐渐减小;在同一条件下,单体的表观增长反应速率常数由大到小依次为丁二烯、苯乙烯和异戊二烯。与正丁基锂体系相比,用锡锂合成的SIBR具有更低的滚动阻力、更好的湿抓着性和物理机械性能。     

n-BuLi/四氢呋喃/t-BuOK体系引发苯乙烯-异戊二烯-丁二烯三元共聚合

以n-BuLi为引发剂,t-BuOK为助引发剂,四氢呋喃(THF)为极性调节剂,己烷/环己烷为溶剂,在聚合温度为60℃时进行苯乙烯-异戊二烯-丁二烯集成橡胶(SIBR)负离子三元共聚合,考察了THF/n-BuLi及t-BuOK/n-BuLi(摩尔比)对SIBR微观结构含量和玻璃化转变温度(Tg)的影响.结果表明:t-BuOK/n-BuLi为0.08时,THF/n-BuLi从5增加到20,三元共聚物中聚丁二烯和聚异戊二烯链段中1,2-结构和3,4-结构质量分数分别增加约2.5%和5.5%,而Tg上升10 ℃左右;当THF/n-BuLi为10时,t-BuOK/n-BuLi从0.04增加到0.15,其聚合物微观结构和Tg变化不明显.     

二乙二醇单乙醚基钡/三异丁基铝/正丁基锂引发体系合成高反式苯乙烯-异戊二烯-丁二二烯三元共聚物

以二乙二醇单乙醚基钡(简称Ba)/三异丁基铝(简称Al)/正丁基锂(简称Li)为三元引发体系,采用负离子聚合法合成了高反式苯乙烯-异戊二烯(Ip)-丁二烯(Bd)三元共聚物(SIBR),考察了引发剂组分、单体配比和聚合温度对SIBR微观结构的影响,并研究了Al/Li(摩尔比)和Bd/Ip(质量比)对SIBR结晶行为的影...     

桐油改性苯丙乳液的合成及在涂料中的应用

以桐油酸、苯乙烯、丙烯酸酯等为共聚单体,过硫酸钾和亚硫酸钠为引发剂,十二烷基硫酸钠和壬基酚聚氧乙烯醚为乳化剂,采用乳液聚合法合成桐油改性苯丙乳液。探讨了桐油酸、乳化剂与引发剂的用量以及反应温度和时间对单体转化率的影响。采用正交试验得到的最佳合成工艺为:m(桐油酸)∶m(苯乙烯)∶m(丙烯酸酯)=1.2∶22.0∶20.0,乳化剂质量分数5.0%,引发剂质量分数0.6%,反应温度85℃,滴加反应时间2 h,保温时间2 h,此条件下单体转化率可达98.3%。相比未加入桐油酸的涂料,桐油改性苯丙涂料的综合性能更好。     

高固含量苯丙微乳液的制备

采用种子半连续微乳液聚合法合成苯丙微乳液。以苯乙烯、丙烯酸丁酯和丙烯酸为单体,辛基酚聚氧乙烯醚(OP-10)和十二烷基硫酸钠(SDS)为乳化剂,过硫酸钾为引发剂,考察了乳化剂、引发剂、丙烯酸单体和电解质对聚合反应的稳定性和粒径大小及其分布的影响,并由此确定了适宜的合成条件,制备了固含量在48%左右,粒径在60~70 nm的苯丙微乳液。     

水性上光油用苯丙共聚乳液的合成及性能表征

以苯乙烯(St)、丙烯酸丁酯(BA)和马来酸酐(MAH)为共聚单体,过硫酸钾(KPS)为引发剂,十二烷基硫酸钠(SDS)/壬基酚聚氧乙烯醚(OP-10)为复合乳化剂,采用半连续加料的乳液聚合法合成出一种水性上光油用苯丙共聚乳液。考察了玻璃化转变温度(Tg)、引发剂和乳化剂含量等对该乳液单体转化率、平均粒径、黏度和表干时间等影响,并对该乳液的热稳定性能进行了研究。结果表明:当w(引发剂)=0.6%、w(复合乳化剂)=1.2%和m(MAH)∶m(BA)∶m(St)=4.6∶36.3∶50.5时,该乳液具有良好的综合性能,完全满足水性上光油的使用要求,并且可在高温环境中使用。     

丁苯乳液共聚合动力学的研究

本文详细考察了高转化率下各种因素对丁苯乳液共聚合速率的影响。以过硫酸钾为引发剂,岐化松香皂和硬脂酸钾的混合物为乳化剂,正十二硫醇为链转移剂,在5升不锈钢高压釜中进行了丁苯乳液共聚合实验。随着乳化剂和引发剂浓度的增大、乳化剂中硬脂酸钾相对量的增加以及温度的升高,聚合速率均加快;加入少量电解质可以提高聚合速率;加入少量硫醇与完全不加硫醇相比,聚合速率有很大提高。另外,还发现氧对聚合有明显的阻聚作用、水油比对单体转化速率影响不大。同时理论推导了乳胶粒数随时间的变化关系,并在自由基聚合机理,乳胶粒中单体浓度连续下降等假设的基础上推导了高转化率下乳液聚合的数学模型,对于丁二烯、苯乙烯共聚体系,模型计算值与实验值能较好的吻合。     

Regulation of molecular weight of styrene–butadiene rubber. III. Choice of regulator from the homologous series of aliphatic mercaptans

The regulating efficiency of four aliphatic mercaptans was studied in emulsion copolymerization of butadiene with styrene, at +5°C. with the use of the redox system, diisopropylbenzene hydroperoxide–complexed ferrous iron–sodium formaldehyde sulfoxylate as an initiator and the sodium soap of disproportionated rosin as an emulsifier. The apparent transfer constants C of tertiary mercaptans decreased logarithmically with increasing length of molecule. This tendency is connected with the analogous dependency of solubilities of these compounds in water. The mercaptans did not affect the rate of polymerization. The value of C is independent of the amount of regulator used. With the value of C, the amount of regulator, and the conversion known, it is possible to predict the molecular weight of the polymers, except for the region of poor regulation, where the deteriorative influence of termination and crosslinking reactions takes place. The apparent transfer constant of tertiary dodecyl mercaptan decreased with increasing rate of polymerization. After elimination of diffuse processes, the value of the actual relative transfer constant was calculated. The tertiary dodecyl mercaptan has been selected as the most convenient molecular weight regulator for emulsion copolymerization of butadiene with styrene of all compounds studied for the system mentioned.     

苯丙乳液的性能研究

以苯乙烯、丙烯酸丁酯、甲基丙烯酸甲酯、丙烯酸为反应单体,过硫酸铵为引发剂,聚乙二醇辛基苯基醚和十二烷基磺酸钠为复合乳化剂,通过连续滴加的乳液聚合工艺制备苯丙乳液。结果表明,当软硬单体配比为1∶1(质量比),SDS∶OP-10=1∶1(质量比),引发剂含量为单体总量的0.3%,可制得较好的乳液。     

Terpolymerization kinetics of N,N‐dimethylaminoethyl methacrylate/alkyl methacrylate/styrene systems

Low conversion kinetics of terpolymerization of N,N‐dimethylaminoethyl methacrylate (DMAEM) and dodecyl methacrylate (DDMA) with methyl methacrylate (MMA) or styrene (ST) was investigated. Reactions were performed at 70°C, in toluene solutions, using peroxide initiator. The interdependence between terpolymer and monomer feed composition was successfully described by Alfrey‐Goldfinger equation and the unitary, binary, and ternary azeotropes were calculated. In MMA‐containing system, the wide pseudoazeotropic region with existence of true azeotropic point was observed and experimentally confirmed at the DMAEM:MMA:DDMA molar ratio of 56:41:3. In the ST‐containing system compositional heterogeneity was significant, more than 10 mol%. Required copolymerization reactivity ratios were determined by linear and nonlinear methods. The glass transition temperatures of synthesized terpolymers are found to be between those of the corresponding homopolymers and relative to their content. Increase in the MMA or ST contents and decrease in the DDMA content in terpolymers results in an increase in their glass transition temperatures. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Preparation and properties of ABA block polymers of styrene and butadiene or isoprene made with sec-C4H9Li·2(C2H5)2O

ABA-type “tapered” block polymers were prepared from styrene (monomer A) and butadiene or isoprene, using an initiator of sec-butyllithium complexed with two molecules of ethyl ether. The stress–strain curves of polymers containing about 20–50% styrene show the usual resemblance to curves of crosslinked elastomers. The SBS polymers had higher tensile strengths than the SIS polymers. They also had slightly higher tensile strengths than comparable SBS polymers made with sec-butyllithium. The SIS polymers, however, had generally lower tensile strengths than those made with sec-butyllithium. This is probably caused by higher styrene content of the isoprene block, brought about by increased randomization of the styrene–isoprene copolymerization due to the presence of the ether. The A and B blocks become more compatible, producing loss of strength in the polymer. Infrared analyses of polydienes made with the sec-C₄H₉Li·2(C₂H₅)₂O initiator showed a 6% to 8% increase in 1,2-content (for polybutadiene) or 3,4-content (for polyisoprene), compared to polymers made with sec-butyllithium. The polymer microstructures still have high (>80%) total 1,4-content, however. Thus, this amount of ether can be tolerated in the polymerization system without great loss of rubbery properties or block structure in the resultant polymers.