MMA-BA-AA共聚反应中单粒径产物影响的研究

选择羧甲基纤维素(CMC)作为稳定剂,过硫酸铵为引发剂,采用种子乳液聚合的方法将甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)进行共聚合成了MMA-BA-AA共聚乳液。研究了羧甲基纤维素用量、引发剂用量、功能单体用量、单体用量和MMA/BA配比对乳液的影响。结果显示,羧甲基纤维素效果显著,既是稳定剂又是接枝底物,CMC用量为0.4%～0.5%,引发剂用量为0.2%～0.35%,丙烯酸AA用量为1%～2%,单体总量应低于45%,MMA/BA配比为1/1～9/7时,制备的乳液较好,且粒径分布呈单峰状态。     

正交实验法优化氟硅丙乳液的制备工艺

利用L25(56)正交实验设计方法,研究了引发剂,乳化剂,有机硅、氟的用量以及聚合温度,单体配比等因素对乳液单体转化率的影响.在本实验条件下,得出制备氟硅丙乳液的最佳工艺条件为:乳化剂用量为4%,引发剂用量为ω=0.6%,单体配比为n(BA):n(MMA)=44:54,有机硅用量ω=10%,有机氟用量ω=4%,聚合温度...     

乙烯基硅烷-丙烯酸酯乳液共聚动力学研究

以乙烯基三乙氧基硅烷(VTES)、丙烯酸酯为单体,乙氧基醇磺基琥珀酸二钠(A—102)为乳化剂,合成了有机硅改性丙烯酸酯共聚乳液。研究了乳化剂、引发剂、VTES、反应温度以及功能性单体甲基丙烯酸羟乙酯(HEMA)对乳液共聚反应速率的影响。结果表明:聚合速率随乳化剂浓度、引发剂浓度、HEMA浓度的增大及反应温度的升高而增大,但随VTES浓度增大而逐渐减小。由实验得出恒速阶段聚合反应速率R_p与乳化剂浓度C_E、引发剂浓度C_1及有机硅单体浓度C_(VTES)的关系为R_p∝C_E~(0.35)C_I~(0.48)C_(VTES)~(-0.64),表观活化能E_a为81.1kJ·mol~(-1)。     

超声无皂乳液聚合制备BA/St/AM三元共聚物乳胶粒及其聚合机理研究

将超声技术引入到无皂乳液聚合方法中,在不加入任何引发剂和乳化剂的情况下,制备了丙烯酸丁酯(BA)/苯乙烯(St)/丙烯酰胺(AM)三元共聚纳米乳胶粒.研究了不同超声时间对单体转化率、乳胶粒粒径以及乳液粘度的影响.同时还探讨了超声无皂乳液聚合机理,认为AM在聚合过程中起到了引发和稳定的作用.TEM照片表明,乳胶粒直径大约在80nm左右,FTIR及DSC分析表明产物为三元共聚物,而不是共混物.     

纳米醋丙乳液的合成与性能表征

以醋酸乙烯酯(VAc)为原料,丙烯酸丁酯(BA)和丙烯酸(AA)为改性单体,过硫酸钾(KPS)为引发剂,OP-10,SDS和可聚合乳化剂丙烯氧基壬基酚聚氧乙烯(10)醚硫酸铵为乳化剂体系,采用半连续种子乳液聚合法制备了纳米粒径的醋丙乳液.对得到的乳液进行了分子量,热性能,红外光谱,乳液稳定性等测试,用激光散射粒度仪和透...     

氧化-还原低温引发苯乙烯/丙烯酸丁酯细乳液聚合粒度分布和成核机理的研究

用氧化还原引发剂(NH₄)₂S₂O₈/NaHSO₃研究了苯乙烯(St)/丙烯酸丁酯(BA)低温下的细乳液共聚合,细乳液单体液滴在亚微米级(100～400nm).测定了聚合过程中粒子大小及分布的变化,发现细乳液聚合随引发剂、乳化剂和共乳化剂浓度的增加,乳胶粒子尺寸变小,分布变宽,并且比相同条件下传统乳液聚合的粒子大.计算了聚合过程中粒子数变化规律及乳化剂覆盖率,讨论了细乳液与传统乳液中引发剂、乳化剂对反应过程的影响及成核机理的差异.     

乳化剂对阳离子乳液聚合及乳胶粒性能的影响

以苯乙烯、丙烯酸丁酯为非离子单体,甲基丙烯酰氧乙基三甲基氯化铵（DMC）为阳离子单体,偶氮二异丁基脒盐酸盐（AIBA）为引发剂,十六烷基三甲基氯化铵（CTAC）和乙撑基双（十六烷基二甲基氯化铵）（G16—2—16）为乳化剂,采用半连续种子乳液聚合法进行阳离子乳液聚合。探讨了乳化剂的分子结构和用量对反应速率、单体转化率以及乳胶粒粒径、Zeta电位等的影响。结果表明：乳化剂的用量越大,反应速率越大,单体转化率越高,而乳胶粒粒径越小;使用G16—2—16作乳化剂时,单体转化率较高,乳胶粒粒径较大,Zeta电位较高。     

反相乳液共聚合制备两性丙烯酰胺共聚物的研究

采用Span80-Tween80复合乳化剂和AIBA引发剂,进行丙烯酸钠(NaAA)/丙烯酰胺(AM)/丙烯酰氧基乙基三甲基氯化铵(DAC)反相乳液共聚合.研究了聚合温度、引发剂用量、单体浓度、共聚单体中DAC和AM含量、乳化剂用量及其HLB值、水/油比和水相pH值等聚合反应工艺条件或参数对聚合反应单体转化率和聚合物特性粘度的影响,聚合物特性粘度随引发剂用量和单体浓度的增大而增大的实验结果证实了该两性丙烯酰胺共聚物反相乳液制备过程中凝胶效应的存在.傅立叶红外光谱组成分析表明了两性丙烯酰胺共聚物的成功合成,扫描电镜观测乳胶粒粒径范围在0.6~8.0μm.     

苯丙乳液合成反应条件优化

以苯乙烯、丙烯酸、丙烯酸丁酯、甲基丙烯酸甲酯等为单体,采用乳液聚合制备了苯丙乳液,研究了合成温度、引发剂用量、乳化剂用量、功能性单体丙烯酸用量等反应条件对苯丙乳液性能的影响,并探讨了丙烯酸单体对乳液耐酸碱稳定性的影响,确定了合成反应条件.结果表明,随着合成温度的提高,混合单体的转化率迅速增加,78℃时转化率最大(达到97.1%),而后随温度继续提高基本保持不变.混合单体转化率随过硫酸钾引发剂用量的增加呈现先增加后逐渐降低的趋势,当过硫酸钾与混合单体质量比为0.010时转化率最大,此时单体转化完全.此外,随着乳化剂用量增加,乳液的外观、钙离子稳定性、凝胶等性能都有所提高,但吸水率也相应增加.最佳合成反应条件为:合成温度为78℃,混合单体组成为15g苯乙烯、2g丙烯酸、18g丙烯酸丁酯、8g甲基丙烯酸甲酯,引发剂和乳化剂与单体质量比分别为0.010和0.035.得到的苯丙乳液在酸性条件下具有良好的稳定性.     

胶乳型互穿聚合物网络研究 Ⅰ.环氧树脂／聚丙烯酸酯半LIPN的制备

采用复合乳液聚合技术,合成了环氧树脂/聚(丙烯酸丁酯—苯乙烯—甲基丙烯酸甲酯)[EP/P(BA—St—MMA)]半胶乳型互穿聚合物网络(semi—LIPN),并探讨了反应温度、乳化剂用量、引发剂用量、不同单体配比、体系 pH 值、搅拌速度、EP 含量、交联剂种类及用量对聚合反应转化率及聚合稳定性的影响。     

高固含量低粘度P(MMA/BA/AA)乳液的制备及性能研究

先利用半连续种子乳液聚合法制备固含量为50%,粒径480nm的单分散甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)与丙烯酸(AA)的共聚物种子乳液;然后以上述种子乳液为介质,十二烷基硫酸钠为乳化剂,碳酸氢钠为缓冲剂,过硫酸铵为引发剂制备固含量72%,乳胶粒具有二元分布特征的高固含量、低粘度稳定乳液:其中大乳胶粒径500～600nm,小乳胶粒径约80nm.所得乳液中乳化剂总含量为聚合物质量的2.1%;粘度在剪切速率为21s-1时为400mPa·s.另外,相对于常规乳液,所制备高固含量乳液胶膜具有更好的光泽度.     

含氢聚甲基硅氧烷/丙烯酸丁酯/羟甲基丙烯酰胺复合乳液的研究——原料配比对乳液及胶膜性能的影响

采用含氢聚甲基硅氧烷（ＰＨＭＳ）与丙烯酸酯类单体进行接枝共聚，制得兼具二者优异性能的新型ＰＨＭＳ／丙烯酸丁酯（ＢＡ）／羟甲基丙烯酰胺（ＮＭＡ）复合聚合物乳液．讨论了ＰＨＭＳ、ＮＭＡ和引发剂用量对该复合乳液的聚合反应转化率、稳定性及粘度的影响．采用透射电子显微镜和粒度测试仪对不同反应条件下制备的乳液的粒度进行了测定．同时对聚合反应的机理、产物的结构及胶膜性能作了考察．结果表明：通过乳液聚合，得到了ＰＨＭＳ／ＢＡ／ＮＭＡ共聚物，控制ＰＨＭＳ、ＮＭＡ、引发剂等用量可制得粒度和粘度适中，具有较高转化率的稳定ＰＨＭＳ／ＢＡ／ＮＭＡ复合聚合物乳液，该乳液所制得的胶膜具有优良的性能     

Butyl acrylate/methyl methacrylate latexes: adhesive properties

In this study, butyl acrylate/methyl methacrylate (BA/MMA) latexes of bimodal molecular weight and particle size distribution were prepared in a multi-step process by seeded conventional emulsion and seeded miniemulsion polymerization. For the conventional emulsion case, a BA/MMA batch copolymerization was conducted as a first step (seed generation) and was followed by a monomer addition step to ensure particle growth. In a third step, a BA/MMA pre-emulsified mixture was added to generate a second particle population. For the miniemulsion case, a BA/MMA copolymerization was carried out as a first step (seed generation) and was followed by a monomer addition step. The addition of a BA/MMA miniemulsion served to generate a bimodal particle size and molecular weight distribution. The final latexes were coated onto a polyethylene terephthalate carrier, dried and their performance as pressure-sensitive adhesives was evaluated using tack, peel and shear adhesion measurements. Structure-property relationships between the adhesive properties and the weight-average molecular weight and average particle size were examined. Even though the polymers obtained by miniemulsion showed better shear resistance, their shear resistance was low. There was no statistically significant difference in peel resistance of the polymers obtained by the two reactions. While a significant difference in tackiness between the two emulsion procedures was found when the adhesives were tested using the less sensitive, rolling ball test, no differences were found when they were tested using a loop tack test.     

MMA-EA-AA无皂乳液聚合中粒径及粒径分布的控制

系统研究了MMA EA AA三元无皂乳液聚合体系中各种因素对乳胶粒大小及分布的影响 ,制得了单分散、粒径在 30 0～ 6 0 0nm可控聚合物乳胶粒 .结果表明 ,在过硫酸铵用量一定的条件下 ,聚合初期加入大量引发剂可同时提高单体转化率和乳胶粒的单分散性 ;随着引发剂和AA用量的增加以及聚合温度的升高 ,胶粒粒径逐渐减小 ,转化率逐渐升高 ;随着NH4 HCO3用量的增加 ,粒径逐渐增大 ,当NH4 HCO3用量达到 0 5g以后 ,转化率逐渐降低 ;搅拌速率为 30 0r min左右时 ,单体转化率最高 ,所得乳胶粒粒径最均一 .     

Butyl acrylate and vinyl acetate semicontinuous emulsion copolymerizations: study of stabilization performance

The use of small amounts of carboxylic monomers in industrial recipes with high solids content enhances colloidal stability due to the presence of carboxylic groups on the outer surface of the polymer particles. Understanding the relationship between several different but interdependent phenomena, including particle nucleation, kinetics, particle aggregation, monomer type, solids content, the role of the carboxylic monomer and the influence of reaction temperature may improve the control over particle size and latex stability. In this work, the kinetics and stabilization performance of semicontinuous vinyl acetate (VA) and butyl acrylate (BA) emulsion copolymerization reactions are studied under different reaction temperatures, acrylic acid (AA) concentrations, solids contents and monomer feed compositions. Results show that choosing optimal AA concentrations and reaction temperatures are key factors in order to enhance the stabilization performance in semicontinuous VA/BA emulsion copolymerization.     

醋酸乙烯酯-丙烯酸丁酯乳液聚合成核机理

本工作研究了醋酸乙烯酯(VA)和丙烯酸丁酯(BA)乳液共聚合.通过对不同共聚单体配比下共聚合时胶乳粒径及胶粒数密度随转化率变化的分析,对VA/BA乳液共聚合成核及粒增长机理进行了探讨,指出水相成核是高VA含量时胶粒数密度较大的主要原因并解释了胶粒数密度及胶乳粒径与单体转化率的关系,同时也讨论了该共聚体系一步法聚合时反应机理与胶粒形态的关系.     

Synthesis and characterization of a novel fluorine-containing polymer emulsion with core/shell structure

A novel fluorine-containing polymer emulsion 4 with core/shell structure was synthesized in water phase by a two-stage emulsion polymerization technique using monomer 3 (i.e., 2-methacryloyloxyethyl perfluorooctanoate (MAEF)) reacting with the monomers such as butyl acrylate (BA), acrylic acid (AA) and styrene (ST). The monomer 3 was synthesized from the intermediate 2 (pentadecafluoro-octanoyl chloride) reacting with β-hydroxyethyl methacrylate (HEMA). Polymer film were prepared by coating emulsion 4 directly on a cleaned glass plate and allowed to dry at room temperature. Moreover, the characteristics of polymer film such as hydrophobicity, chemical resistance, surface composition, thermal stability, emulsion particle morphology, as well as the film-forming property were also studied.     

反应性乳化剂存在下的五元苯丙乳液共聚合

采用反应性乳化剂SE-10N,通过正交实验及单因素实验确定了以苯乙烯、甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸和丙烯腈为单体的五元无皂苯丙共聚乳液的组成及聚合工艺。所制得的无皂乳液稳定,其乳胶粒大小均匀,粒径为50~60nm,比同组成的有皂乳液乳胶粒的粒径稍小。乳液涂膜透明、硬度达H级;其硬度、耐水性及钙离子稳定性均较同组成有皂乳液的好。     

Emulsion terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate: Experimental results

A systematic study of the terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate (BA/MMA/VAc) was conducted. In this stage of the study, batch emulsion terpolymerizations were performed in a 5 L stainless steel pilot plant reactor. The experiments were designed using a Bayesian (optimal) technique. The polymers produced were characterized for conversion, composition, molecular weight, and particle size. Conversion, terpolymer composition, number- and weight-average molecular weight, and average particle size results are discussed in light of the influence of seven factors and the interaction of these factors. The factors studied include monomer feed composition, initiator concentration, chain transfer agent concentration, impurity concentration, initiator type, emulsifier concentration, and temperature. A “two-stage rate” phenomenon, similar to that occurring in bulk co- and terpolymerization and emulsion copolymerization of acrylic/vinyl acetate systems was observed in the conversion, composition and molecular weight data. Furthermore, an interesting yet often ignored effect of impurities on emulsion polymerization kinetics was explained. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1659–1672, 1997