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1.
采用乳液聚合法将甲基丙烯酸甲酯(MMA)接枝到氯丁胶乳上,红外光谱和核磁共振氢谱证实了接枝产物的生成。研究了反应温度、乳化剂浓度、引发剂浓度和单体浓度对表观聚合速率的影响。结果表明,当反应温度为50℃,引发剂叔丁基过氧化氢-四乙烯五胺(t-BHP/TEPA)用量为氯丁胶乳干重的0.5%,单体/聚合物质量比m(M):m(P)=3:5,乳化剂十二烷基连苯醚二磺酸钠(DSB)用量为单体总质量1%时,单体转化率和接枝效率分别为99.1%和54.9%。聚合反应动力学关系式为:Rp=Kc(E)0.15c(I)0.30c(MMA)1.41,式中,K为常数,在40~55℃范围内,聚合反应的表观活化能Ea=60.2kJ/mol。接枝聚合基本符合自由基反应机理。  相似文献   

2.
将γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPS)接枝到凹凸棒土(AT)表面,制得表面带有可聚合碳碳双键的改性粒子AT-MPS;以二硫代苯甲酸氰基异丙酯(CPDB)为链转移剂,采用可逆加成断裂链转移(RAFT)聚合技术,在AT表面进行甲基丙烯酸甲酯(MMA)接枝聚合.通过红外(FTIR)、热失重(TGA)等方法进行了表征,考察了引发剂以及RAFT链转移剂用量对聚合反应动力学和AT表面接枝聚合接枝率的影响.结果表明,PMMA通过RAFT聚合成功接枝在AT表面;基于RAFT过程的接枝聚合比传统自由基接枝聚合具有更长的反应时间和较高的接枝率.本体系相对适宜条件:温度为70℃,[MMA]/[CPDB]/[AIBN]为400/1/0.5.此条件下聚合反应具有很好的可控性,溶液中的聚合物分子量分布指数为1.2~1.3,AT表面PMMA接枝率为16.33%.引发剂和RAFT链转移剂用量过大均会造成接枝率降低.  相似文献   

3.
淀粉接枝聚丙烯酰胺反相胶乳的胺甲基化反应   总被引:13,自引:0,他引:13  
淀粉接枝聚丙烯酰胺反相胶乳的胺甲基化反应卢绍杰刘瑞贤孙希明卫乃勤杨光中(天津大学化学系300072)关键词反相乳液淀粉接枝Mannich反应阳离子淀粉接枝聚丙烯酰胺是聚丙烯酰胺有重要应用价值的改性产品,在采油、造纸、水处理等部门有着广泛的应用。它的制...  相似文献   

4.
5.
甲基丙烯酸甲酯聚合动力学和分子量模型及仿真   总被引:2,自引:0,他引:2  
考虑甲基丙烯酸甲酯聚合过程中体积收缩,反应物和生成物的浓度变化,以及由于凝胶、玻璃化和笼闭等效应对各速率常数和物性参数的影响,从基元反应和物料平衡出发,推导了半间歇,有链转移剂参与情况下的聚合动力学和分子量模型。用模型仿真计算了聚合温度、引发剂、溶剂和链转移剂的种类和浓度等对甲基丙烯酸甲酯聚合动力学和聚合过程中分子量变化的影响规律,并与实验和文献数据进行比较。  相似文献   

6.
采用Nd(P507)3-Al(i-BU)3聚合体系催化甲基丙烯酸甲酯(MMA)和甲基丙烯酸丁酯(BMA)聚合.发现介质对聚合反应速率影响甚大.在石油醚中聚合反应速率与单体(MMA、BMA)、钕盐的浓度分别呈一级关系.MMA.BMA聚合的表现活化能分别为33kJ.mol-1和24kJ.mol-1.PMMA的间同含量达70%左右.聚合反应属配位自由基机理.  相似文献   

7.
微乳液反应法制备聚甲基丙烯酸甲酯超细粒子   总被引:3,自引:0,他引:3  
水/油微乳液;微乳液反应法制备聚甲基丙烯酸甲酯超细粒子  相似文献   

8.
等离子体挥发性产物引发甲基丙烯酸甲酯聚合反应动力学   总被引:1,自引:0,他引:1  
本文发现甲基丙烯酸甲酯等离子体挥发性产物能够有效地引发单体聚合,获得超高分子量聚合物。其聚合过程属于瞬时引发、向单体链转移的活性自由基聚合机理。  相似文献   

9.
通过比较在大水油比下的甲基丙烯酸甲酯 (MMA)悬浮均聚的实验数据以及本体聚合实验结果 ,发现单体的水溶性对其聚合动力学有影响 ,不能用本体聚合动力学代替其悬浮聚合动力学 .为了能更好了解单体的水溶性对其悬浮聚合动力学的影响以及影响动力学的原因 ,在MMA本体聚合动力学模型基础上 ,进一步提出 3个假设 :扣除溶于水相部分的单体量、增长和终止速率参数降低、少部分的油溶性引发剂被带到水相中 ,得到改进的悬浮聚合动力学模型 .运用该模型能很好预测水油比、聚合温度、引发剂浓度等对MMA悬浮聚合动力学的影响 ,且与实验数据能较好吻合  相似文献   

10.
使用锥形量热仪研究了3 mm厚、 100×100 mm2的透明聚甲基丙烯酸甲酯(PMMA)板在不同温度下的燃烧反应,采用化学动力学法拟合了PMMA燃烧过程中质量损失率a与时间t的单方程速率模型.结果显示,在PMMA燃烧过程中,质量损失速率受产物的解吸附和扩散过程控制.PMMA在584~800℃燃烧时,合适的反应动力学方程为[-ln(1-a)]1/4=Ae-E/RT t,其中指前因子A约等于0.1239 s-1,平均表观活化能E约为22.81 kJ/mol,并与温度的变化基本无关,计算结果与实验数据吻合较好.  相似文献   

11.
张彬  张兆斌  万小龙  胡春圃  应圣康 《化学学报》2003,61(12):2008-2012
以卤化亚铜(CuX)/1,10-邻二氮菲(phen)配合物为催化剂、2-溴代异丁酸 乙酯(EBiB)为引发剂、十二烷基磺酸钠(SLS)为乳化剂,进行了甲基丙烯酸甲 酯(MMA)的原子转移自由基乳液聚合(ATRP)反应。结果表明,与较高温度(70 - 90 ℃)下的聚合反应相比,室温(25 ℃)时聚合反应有更好的可控性,通过 外加钝化剂的复合催化引发体系CuBr/CuBr_2/phen/EBiB或利用CuCl/phen/EBiB催 化引发体系的“卤素交换反应”,可进一步改善聚合反应的可控性。紫外发光谱测 定结果表明,CuBr/phen配合物在MMA相中的分配倾向随着温度的降低而增大,使得 室温下MMA的乳液ATRP保持了较好的可控性和较快的反应速度。  相似文献   

12.
Polymerization rate and molecular weight development experimental results for the emulsion polymerization of methyl methacrylate (MMA), in the presence of potassium persulphate (PPS) as initiator, and activated with a 50 W microwave source, are reported. The polymerization kinetics of the microwave activation experiment (MA) was compared against a traditional conductive heating (CH) polymerization reaction. The number average molecular weights, Mn, of the polymer samples obtained with microwave activation were significantly higher than those obtained from conductive heating. These high values of Mn were obtained from the beginning of the polymerization reaction. Polydispersity index (PDI) values in the range of 1.18 to 1.83 were obtained in the microwave irradiated samples. These values are lower than those produced by conventional emulsion polymerization of styrene and other vinyl monomers, and resemble the PDI values obtained in controlled‐radical polymerization processes. Polymer particles of submicron size (60 to 100 nm) were obtained.  相似文献   

13.
茂基二苯胺基镱配合物催化甲基丙烯酸甲酯聚合  相似文献   

14.
聚硅氧烷/甲基丙烯酸甲酯核壳结构复合粒子的制备   总被引:9,自引:0,他引:9  
聚硅氧烷/甲基丙烯酸甲酯核壳结构复合粒子的制备;种子乳液聚合;核壳结构  相似文献   

15.
Soap-free emulsion polymerization of methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA) was carried out in the presence of colloidal nano-SiO2 particles. The effect of nano-SiO2 level on the monomer conversion, polymerization rate (Rp), and emulsion stability was investigated. The viscosity, particle size distribution of the emulsions, surface tension, and ionic conductivity of these systems were determined. Upon the introduction of the nano-SiO2 particles into this system, the Rp and monomer conversion increased and the average particle size of the P(MMA-HEMA) emulsion decreased in comparison to emulsions formed in the absence of nano-SiO2. However, the particle size distribution became broader to some degree. Scanning electron microscope observations demonstrated that the shape of these latex particles were uniformly spherical. The surface tension and ionic conductivity of the system increased significantly after polymerization, but the presence of nano-SiO2 resulted in an increase in surface tension and a decrease in ionic conductivity in comparison to the particle–free system.  相似文献   

16.
李松军  胡杰  刘白玲 《合成化学》2004,12(4):359-364,J003
在自由基聚合反应中,每个聚合物分子都是经历成百上千次加成聚合形成。由于聚合次数不完全相同造成实际链长的不等性,故由稳态近似法所获得的结果只是一个平均的概念,对反应未达平衡态时不适用。本文运用统计的方法,克服了非稳态方法的限制。通过从任意时间微元扩展至反应结束,获得了甲基丙烯酸甲酯聚合反应相应的统计关系式,如聚合物的数量、重量分布及聚合物的平均分子量等,对深入了解高分子化学反应的本质具有重要的价值和意义。  相似文献   

17.
Organomanganate reagents [R3Mn]Li+ (R = Bu, Me) were found to polymerize methyl methacrylate in the presence of potassium tert‐butylate. A conversion of the tacticity of the resulting poly(methyl methacrylate)s from heterotactic (mr = 54%) to isotactic (mm = 58%) was observed upon changing the R group of the initiator from Bu to Me. The addition of triisobutylaluminium was found to efficiently control w and w/n of the resulting polymers.  相似文献   

18.
Summary: Experimental data are discussed challenging the deterministic kinetics of emulsion polymerization. Examples are given for the overall rate of polymerization, in-situ stabilizer formation, and swelling of latex particles. Improving the deterministic view on emulsion polymerization kinetics requires the consideration of results of molecular modelling and the application of multiscale integration techniques.  相似文献   

19.
将等离子体接枝技术,用于原生态聚丙烯接枝甲基丙烯酸甲酯共聚物的合成。FT-IR证明所得产物为接枝共聚物,研究了不同等离子体处理功率、时间,不同接枝聚合反应时间、温度对接枝的影响,以及稀释剂、聚丙烯粒度对接枝的影响。结果表明,接枝过程中有自动加速现象,稀释剂亦使接枝有加速效应。接枝过程为扩散控制过程。  相似文献   

20.
Methyl methacrylate and butyl acrylate monomers are copolymerized by atom‐transfer radical polymerization, affording polymers with well‐controlled molecular weight and low polydispersity. A kinetic analysis of this system is compared with the corresponding free‐radical polymerization system. The copolymerization rate follows an opposite trend to that observed in conventional copolymerization. This fact is attributed to a smaller population of radicals generated in the reaction, since the relative fraction of propagating radicals is the same as that in classical copolymerization.  相似文献   

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