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丙烯酸酯反相微乳液聚合动力学 总被引:3,自引:1,他引:2
对以甲基丙烯酸甲酯/丙烯酸丁酯混合单体为连续油相、十二烷基硫酸钠为乳化剂、丙烯酸为反应性助乳化剂构建的反相微乳液体系,以偶氮二异丁腈引发微乳液聚合,系统考察了引发剂浓度、乳化剂浓度、助乳化剂浓度、水相质量分数及反应温度对表观聚合速率的影响.讨论结果表明,微乳液聚合中液滴成核相当重要,聚合速率随体系中引发剂浓度、丙烯酸浓度、水相质量分数及聚合温度的升高而加快,随体系中乳化剂浓度的增大而降低,并得出动力学关系式,且聚合反应表观活化能为114 kJ8226;mol-1. 相似文献
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脂肪酸甲酯磺酸钠作乳化剂的丙烯酸酯乳液聚合研究 总被引:2,自引:0,他引:2
以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸为单体,脂肪酸甲酯磺酸钠C16-MES为乳化剂,通过乳液聚合制备了丙烯酸酯共聚物乳液.根据Davies法计算了C16-MES的HLB值在12.8左右,并且考察了乳化剂用最、引发剂种类及用量、单体配比对聚合稳定性及乳液稳定性的影响规律.实验结果表明,以C16-MES为乳化剂制备的不同单体配比的丙烯酸酯共聚物乳液稳定,随着乳化剂用量的增加,聚合反应速率增大;引发剂用量相同时,氧化还原引发体系引发的丙烯酸酯乳液聚合速率大于热引发体系.乳胶粒的粒径都在103~200 nm. 相似文献
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聚氨酯预聚体——可聚合乳化剂用于MMA乳液聚合动力学及聚合稳定性研究 总被引:1,自引:0,他引:1
将合成的聚氨酯预聚体可聚合乳化剂(APUA)用于甲基丙烯酸甲酯(MMA)乳液聚合体系中,研究了不同引发剂体系和乳化剂对聚合体系的聚合稳定性和动力学影响,并与SDS乳化剂进行了对照。结果显示,用油溶性引发剂(AIBN)和水溶性引发剂(K2S2O8)都能引发该体系的聚合反应,而且聚合速率和转化率都相当高。用AIBN作引发剂时,APUA和SDS两种乳化所对应的动力学曲线不同,但APUA比SDS的聚合速率大得多,其分别类似于微乳液聚合(miniemulsion)和微悬浮聚合(microsuspention),且聚合过程中会产生一定的凝胶。当乳化剂APUA用量适合时,凝胶量极少,聚合体系是稳定的;而当用K2S2O8作引发剂时,两乳化剂对应动力学曲线相似,聚合过程不产生凝胶。但当引发剂用量较大并以APUA作乳化剂时,在聚合过程中会出现全部粒子突然粗化现象,而以SDS作乳化剂没有出现这一现象。 相似文献
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反相乳液聚合合成聚丙烯酰胺 总被引:1,自引:0,他引:1
以甲苯为介质,Span80/Span20为乳化剂,叔丁基过氧化氢/亚硫酸氢钠氧化还原体系为引发剂,采用反相乳液聚合制备了分子量高达9.4×106的聚丙烯酰胺乳液。研究了乳化剂种类及用量、引发剂种类及用量、油水比、单体浓度,反应温度对共聚物相对分子量、聚合转化率以及聚合反应速率的影响。其最佳聚合配方及工艺条件为:油水体积比为1.4,单体浓度30%,引发剂用量0.003%,乳化剂用量12%,聚合温度30℃。 相似文献
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乙烯基硅氧烷改性丙烯酸酯乳液聚合的动力学及成核机理分析 总被引:9,自引:0,他引:9
用种子乳液聚合法研究了硅氧烷改性丙烯酸酯的乳液聚合,对影响种子乳液聚合动力学的因素进行讨论,并分析了乳液聚合的成核机理.实验结果表明:反应温度、引发剂浓度、乳化剂浓度和有机硅氧烷用量对有机硅改性丙烯酸酯乳液聚合动力学有较大的影响.反应温度越高,引发剂浓度越高、乳化剂浓度越高、有机硅氧烷用量相对较小,乳液聚合反应的转化率越高;此外,体系的pH值在6~8之间时也有利于反应的进行.种子乳液聚合中RP∝[E]0.72,RP∝[I]0.56,表观活化能Ea为143.92 kJ8226;mol-1.种子乳液聚合初期,反应主要是单体液滴成核;进入壳层反应时,反应成核主要是以胶束成核为主. 相似文献
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以过硫酸铵为引发剂,用超声波引发丙烯腈单体进行无皂乳液聚合,研究了单体浓度、引发剂浓度、反应时间对单体转化率的影响情况,并对聚合物进行了IR、TEM表征,结果显示聚丙烯腈乳胶粒尺寸均匀,约为50nm。 相似文献
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Mohammed A. Bahattab 《应用聚合物科学杂志》2011,121(5):2535-2542
The low water solubility of styrene (St) monomer increase the need for a good initiator system to speed up the emulsion polymerization and remove unreacted monomers. Polymerization of styrene monomer in water was performed at 30, 50, and 70°C under ultrasonic irradiation using sodium dodecyl sulfate as surfactant and ammonium persulfate as initiator. Ultrasonic energy was used as a tool to speed up the polymerization. Combining ultrasonic and ammonium persulfate led to a higher conversion and higher rate of polymerization. Ultrasonic energy has an effect on the particle size distribution. The particle size distribution increases with an increase in the monomer conversion of styrene for ultrasonic polymerization, whereas the particle size distribution did not change with an increase in the monomer conversion compared with the conventional thermal polymerization results. Higher molecular weights were obtained under ultrasonic irradiation. FE‐SEM and TEM pictures show different morphology with changing temperature polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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苯乙烯改性丙烯酸酯类乳液的合成及性能研究 总被引:2,自引:0,他引:2
采用半连续预乳化聚合方法合成苯丙乳液,研究了聚合温度、反应时间、乳化剂用量及引发剂用量对单体转化率和聚合稳定性的影响;探讨了不同MMA/St配比对单体转化率、乳液粒径、胶膜吸水性及耐热性的影响。对共聚物进行了红外分析。结果表明,当乳化剂用量为2.5%、引发剂0.5%、聚合温度为80℃、反应时间120min、mMMA/mSt=6:4时,能得到各项性能指标优异的苯丙乳液,合成产品的耐水性和耐热性都较纯丙乳液有明显提高,产品可用作静电植绒粘合剂。 相似文献
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Polystyrene latex particles were synthesized using a method based on emulsifier‐free miniemulsion polymerization under ultrasonic irradiation in the presence of 2,2′ azobis (2‐amidinopropane) dihydrochloride (V‐50) as a cationic ionizable water‐soluble initiator and cetyl alcohol as costabilizer. The optimized conditions were obtained by using various parameters, such as the amounts of monomer and initiator, and the time and power of ultrasonic irradiation. In optimal conditions, the latex particles appeared to be about 250 nm in diameter through scanning electron microscopy (SEM). The SEM and gel permeation chromatography (GPC) analyses and monomer conversions of emulsifier‐free miniemulsion polymerization were compared with those of conventional emulsifier‐free emulsion polymerization using V‐50 as initiator in both cases. The results showed that in the miniemulsion polymerization, the rate of polymerization (Rp) was significantly higher, and latex particles were significantly smaller than those in the conventional emulsion polymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
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以丙烯酰胺(AM)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,失水山梨糖醇脂肪酸酯(Span 80)和失水山梨醇单油酸酯聚氧乙烯醚(Tween 80)为乳化剂,液体石蜡为油相,2,2'-偶氮二异丙基咪唑啉二盐酸盐(VA-044)为引发剂,研究AM与DMC反相乳液聚合动力学,反相乳液聚合速率方程为Rp=k[M]2.12[I]0.55[E]0.65,AM与DMC反相乳液聚合表观活化能为80.65 kJ·mol-1。通过反相乳液聚合速率随时间的变化关系得出其成核机理倾向于单体液滴成核。用Fireman-Ross法研究了共聚单体竞聚率,分别为rAM=0.23、rDMC=1.93,AM与DMC在聚合物链上发生无规共聚反应。单体量增大、引发剂量减少、乳化剂量增大、聚合温度降低均使共聚产物的特性黏数增大。 相似文献
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以概率论中的大数法则和中心极限定理为基础,通过对成核阶段条件的简化,建立了丁二烯/苯乙烯乳液聚合成核阶段的Monte Carlo模型,模拟考察了乳化剂、引发剂浓度对丁苯乳液聚合反应速率的影响,对丁苯乳聚成核阶段模拟结果进行回归表明,乳胶粒数目N p与乳化剂浓度[S]和引发剂浓度[I]的关系为:N p=k[S]0.606 2[I]0.405 5,与Smith-Ewart经典理论相吻合。改善乳液聚合生成的乳胶粒径分布以及乳胶粒数目是提高乳液聚合中单体转化率最为有效的方法。模拟计算结果表明,将单体转化率从62%提高到70%,引发剂浓度的增加量应在12.90%~34.89%(摩尔分数)之间,乳化剂浓度的增加量应在12.6%~22.16%(摩尔分数)之间。与实验结果进行对比,数据吻合,验证了模拟计算的可靠性和有效性。 相似文献
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The kinetics of dispersed phase polymerization of a highly water‐insoluble monomer (isooctyl acrylate) were explored in emulsion, miniemulsion, and microsuspension polymerization. The effects of monomer water solubility and choice of initiator (oil‐ vs. water‐soluble) strongly impact the final product (particle size and molecular weight distribution). For emulsion polymerization, as the surfactant concentration was increased, there was a transition from homogenous to micellar nucleation near the CMC, then a drop in nucleation rate at high surfactant concentration due to insufficient radical flux to support more nucleation. For miniemulsion polymerization, a slow rate of growth of (droplet) nucleation with surfactant concentration was found, followed (at the CMC) by an increase in the rate of nucleation with added surfactant as the mode of nucleation switched to micellar. The conversion‐time kinetics of microsuspensions could be modeled with a bulk polymerization model. IOA is sufficiently insoluble in the aqueous phase that emulsion polymerization may or may not be reaction limited. The presence of a stabilizer such a PAA, the use of an oil‐soluble initiator such as BPO, and the insolubility of IOA in the aqueous phase all push the polymerization locus toward droplet (microsuspension) nucleation and bulk kinetics.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5649–5666, 2006 相似文献