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1.
N-烯丙基咔唑不能均聚合,但可与甲基烯酸甲酯在高温下共聚合。测定了200-260℃时两单体体共聚合,竞聚率,温度为250℃时,r1和r2均小于1。共聚分子量随着共聚温度升高而降低。结果表明,共聚体系中,增长反应与降解反庆同时存在。该反应可能是自由基过程。  相似文献   

2.
2-亚甲基-丁二酯酐和甲基丙烯酸甲酯在四氢呋喃中以过氧化二苯甲酰作引发剂进行自由基共聚合。由作图法求得这两种单体在66℃的共聚竞聚率:r1=4.22,r2=0.64,表明它们趋于嵌均共聚。用粘度法和GPC测量了共聚物的分子量和分子量分布。  相似文献   

3.
采用红外光谱分析共聚物组成的方法,测定了不同温度下甲基丙烯酸三了基锡酯(ThTM)和甲基丙烯酸甲酯(MMA)在甲苯溶液中的自由基共聚合竞聚率.并用F—R法、M—L法和EVM法处理了实验结果,讨论了不同的数据处理的方法对共聚合竞聚率数值的合理性和准确性的影响.随聚合温度的升高,TBTM和MMA逐渐倾向于理想共聚合.由共聚温度与r1和R2的关系得到各温度下最为合理的r1和r2值,并讨论了聚合温度对共聚活性的影响.  相似文献   

4.
用^1H-NMR分析法测定了丙烯酸-β-羟乙酯(M1)和甲基丙烯酸正丁酯(M2)的共聚物组成,用Mayo-Lewis模型的误差变量法计算出不同温度下该体系的溶液聚合的竞聚率,分别为r1=0.63,r2=1.17(60℃);r1=0.61,r2=1.01(80℃);r1=0.61,r2=0.97(100℃);r1=0.70,r2=1.03(120℃);r1=0.68,r2=0.88(140℃)和r1=0.66,r2=0.86(160℃)。根据Arrhenius方程计算获得了体系均聚、共聚反应频率因子之比Aii/Aij和活化能之差Eii-Eij,并讨论了溶剂、氢键对共聚合单体活性的影响。  相似文献   

5.
用微臭氧化-薄层层析法分析测定了复合催化剂AlCl_3/SbCl_3,在不同Sb/Al比、投料比、溶剂和温度等条件下的α-菠烯(M_1)/苯乙烯(M_2)共聚产物的构成,表明该复合催化剂可获得~100%共聚体,其中α-蒎烯链节含量F1可在30%~56%之间调控。在仅生成共聚体的条件下由Mayo-Lewis积分式首次测定了竞聚率。AlCl_3/SbCl_3和单独AlCl_3相比,r1增大,r2减小,r2/r1值降低了5~6倍,使不易共聚的M_1/M_2变为易于共聚,可制备M_1组分含量高的共聚体。确认该复合催化剂对M_1/M_2的优良共聚合性能在于阳离子聚合活性种的非质子和抗衡阴离子(团)的特殊结构和性质.  相似文献   

6.
研究了二叔丁基羟胺(DTBHA),二叔丁基氮氧自由基(DTBNO·),2,2,6,6-四甲基-4-羟基哌啶羟胺(TMHPHA)和2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基(TMHPO·)对过氧化苯甲酰(BPO)60℃引发的苯乙烯(M1)-丙烯腈(M2)共聚合的阻聚行为.结果表明,这些阻聚剂对St-AN共聚均表现良好的阻聚行为,其中氮氧自由基优于相应羟胺.同时观察到St—AN竞聚率的改变,羟胺使r1有所降低,r2略有增大.但相应的氮氧自由基是相反结果.阻聚剂为200ppm时,共聚物中的恒比共聚点由对照实验的0.619变化为0.533,0.645,0.589和0.698相对于DTBHA,DTBNO·,TMHPHA和TMHPO·.  相似文献   

7.
在亚乙基双( 茚基) 二胺化茂铪(rac C2H4(Ind)2Hf(NMe2)2 ,简称1 ,Ind = 茚基,Me= 甲基) 催化作用下,对乙烯(E) 与1 辛烯(O) 无规共聚合进行了研究.作为比较,利用异亚丙基( 环戊二烯基)(1 芴基) 二甲基锆茂催化体系((CH3)2C(Fluo)(Cp)ZrMe2 ,简称2 ,Fluo = 芴基,Cp = 环戊二烯基) 对乙烯/1 辛烯在相同共聚合条件下进行了共聚合.结果表明,在单体浓度比[O]/[E] 较小时共聚合速率随单体浓度比增加而增加,进一步增加单体浓度比则导致共聚合速率降低.催化体系1/Al(iBu)2H/[Ph3C][B(C6F5)4](3) 催化共聚活性比2/ MAO高得多.共聚物中辛烯含量随反应单体1 辛烯含量的增加而增加,两单体竞聚率乘积( rE×ro) 小于1 ,表明聚合物为无规共聚物.相同共聚单体浓度比下1/Al(iBu)2H/3 催化共聚物中辛烯含量比2/ MAO 共聚物中辛烯含量高,表明前者具有更强的共聚合能力.所得无规共聚物熔点温度、结晶度、本体粘度及密度随共聚物中辛烯含量的增加而显著降低.辛烯含量较高时共聚物呈现明显无结晶行为.差示扫描量热分析显示,同乙烯均聚?  相似文献   

8.
研究了稀土配位催化剂对难以开环均聚和共聚的环硫氯丙烷(CMT)与环氧氯丙烷(ECH)的共聚合。发现稀土乙酰丙酮盐、环烷酸盐等与异丁基铝、水组成的络合催化剂有良好的催化活性,能制备得到类交替共聚物,产率高达60%以上,分子量频高([η]=0.15dL/g)。应用IR、^13C NMR、GPC、VPO等测试手段对共聚物的结构和分子量进行了表征。测定CMT(1)与ECH(2)共聚合的竞聚率分别为r1=0  相似文献   

9.
对130℃下1,3 二烯基 1,1,3,3 四甲基二硅氧烷(DVDS)/苯乙烯(St)的溶液环化共聚合动力学进行了研究.根据低转化率(<10%)的共聚物组成及环状结构比例,通过参数估计方法,求得环化率与竞聚率,分别为r1=0102、r2=348、rc=00210、Kc=381mol/L、K′c=0389mol/L,同时得到它们95%置信概率的联合置信区间及其交互影响的联合置信区间.表明DVDS的反应活性较St低,其非环状结构自由基具有较强的分子内环化反应能力;环的位阻效应使环状结构DVDS自由基的活性低于其非环状结构自由基.  相似文献   

10.
将(2-甲基丙烯酰氧乙基)三甲基氯化铵(DMMC)与丙烯酰胺(AM)在聚乙二醇(PEG)水溶液中进行双水相共聚合(ATPC),并与DMMC/AM均相水溶液共聚合(HASC)进行比较.在均相水溶液共聚合体系中得到了DMMC/AM共聚体系的竞聚率分别为rDMMC=1.77、rAM=0.32,并给出了竞聚率的95%,99%联合置信区域.比较了两种共聚合体系的转化率-时间曲线和共聚组成,表明双水相共聚合体系初期反应速率高于均相水溶液共聚合体系,但最终转化率相似;两种共聚合体系得到的共聚物组成有较大差别.测得了DMMC、AM以及DMMC-AM共聚物(CPAM)在65℃、反应条件下的相分配系数为K1=0.035、K2=0.125和Kp=0.011.结合双水相聚合的本质以及单体和共聚物在两相的分配系数,提出了一个计算双水相共聚组成的新方法,用该方法计算的双水相共聚合体系的共聚组成与实验点吻合较好.  相似文献   

11.
应用气相色谱法研究了温度对丙烯腈-丙烯酸甲酯水相沉淀共聚合竞聚率的影响,测得30℃时r_1=0.96,r_2=1.18;40℃时r_1=0.83,r_2=1.17;50℃时r_1=0.70,r_2=1.17;60℃时r_1=0.68,r_2=1.10,竞聚串与反应温度的关系为:1nr_1=-4.043+1207/T,1nr_2=-0.01360+51.68/T。发现共聚物沉淀粒子的表面吸附作用对该共聚体系竞聚率的温度依赖性有很大影响。  相似文献   

12.
The novel redox system, potassium diperiodatonickelate (Ni(IV))-casein, was used to initiate graft copolymerization of butyl acrylate onto casein under heterogeneous conditions in aqueous 5% potassium hydroxide solution, which showed high grafting efficiency and percent grafting. FT i.r. spectroscopy, thermal analysis and scanning electron microscopy characterized the structures and properties of the grafted copolymer. The effects of synthesis variables in the graft copolymerization have been discussed in the light of grafting efficiency, percent grafting and the rate of polymerization. A possible initiation mechanism is proposed.  相似文献   

13.
The graft copolymerization of 4-vinylpyridine (4-VP) onto cellulose has been carried out in heterogeneous conditions with cobaltacetylacetonate complex (Co (acac)3) under nitrogen atmosphere at 35±0.1°C in aqueous media. The grafting parameters such as graft yield, grafting efficiency, total conversion, frequency of grafting and rate of grafting have been evaluated as a function of concentration of 4-vinylpyridine, cobaltacetylacetonate and reaction temperature of graft copolymerization. Variation in concentration of monomer and initiator leads to a consistent increase in grafting parameters and then show a decreasing trend. The efficient grafting of monomer in presence of cobaltacetylacetonate complex is due to the coordination of the -electrons of the 4-vinylpyridine with the metal chelate which facilitate the homolytic decomposition of metal-oxygen bond to form radicals at relatively low temperature. The rate of graft copolymerization is directly proportional to the concentration of monomer and the square root of the concentration of the cobaltacetylacetonate complex. The activation energy (Ea) for graft copolymeriztion has been calculated using a Arrhenius plot and is 31.0kJ mol–1 within the temperature range of 20–40°C. The grafting of 4-vinylpyridine has also been studied in presence of various additives and their effects have been suitably explained. On the basis of the experimental observations, reaction steps are proposed and rate expression has been derived.  相似文献   

14.
The combination of MALDI-ToF-MS and pulsed laser polymerization has been used to study the propagation rate coefficients for the copolymer system styrene-methyl methacrylate. For the first time, complete information regarding mode of termination, reactivity of photoinitiator-derived radicals, copolymer molecular mass, chemical composition, and copolymerization rates is obtained interrelated. The polymerizations were carried out in bulk with varying styrene concentrations at a temperature of 15.2 degrees C by an excimer pulsed laser with varying frequencies. Both chemical composition distributions and molecular weight distributions were determined by MALDI-ToF-MS. The data were fitted to the implicit penultimate unit model and have resulted in new point estimates of the monomer and radical reactivity ratios for the copolymer system styrene-methyl methacrylate: r(St) = 0.517, r(MMA) = 0.420, s(St) = 0.296, s(MMA) = 0.262. Comparison between Monte Carlo simulations and the obtained results further confirmed the very successful combination of pulsed laser copolymerization experiments with MALDI-ToF-MS. The obtained results are believed to be the most accurate and complete set of copolymerization parameters to date.  相似文献   

15.
研究发现无水稀土氯化物 50%发烟硫酸体系是四氢呋喃(THF)均聚和四氢呋喃与环硫氯丙烷(CMT)共聚合的优良新催化体系.考察了THF均聚反应特征,在合适条件下,THF聚合以65%转化率制得粘均分子量达10,000~15,000的白色聚四氢呋喃(PTHF)固体.端羟基分析法测得聚合物的分子链两端均为羟基.考察了影响THF CMT共聚合反应诸因素,如聚合温度和时间、两单体的比例等,制得数均分子量为1,000左右的淡黄色粘性固体共聚物.  相似文献   

16.
The low-temperature copolymerization of N-vinylpyrrolidone with acrylic monomers (acrylic acid, acrylamide, and methyl acrylate) in vitrifying solutions in ethanol and DMF has been studied. It has been shown that the copolymerization proceeds after transition of preliminarily γ-irradiated at 77 K samples from the solid glassy state to a supercooled liquid. Experimental conditions that ensure formation of alternating and random block copolymers have been established. The composition of copolymers is determined by the relative mobility and initial ratio of comonomers in solution.  相似文献   

17.
近年来,新的有机锡聚合物的合成及其在许多领域内的应用研究取得很大的进展,然而,侧链上带有有机锡基团的二烷(芳)基锡聚合物的研究报道较少。众所周知,二烷基锡化合物是一类重要的聚氯乙烯热稳定剂。制备对聚氯乙烯具有改性作用的有机锡共聚合型热稳定剂,以实现聚氯乙烯热稳定剂的高分子化和多功能化,是未来热稳定剂的发展方向之一。我们已研究了顺丁烯二酸二丁基锡酯分别与苯乙烯、甲基丙烯酸甲酯的共聚反应及其共聚物对聚氯乙烯热稳定性的影响。本文报道顺丁烯二酸二丁基锡酯分别与丙烯酸甲酯、丙烯酸丁酯的共聚反应。  相似文献   

18.
以载体型钛系齐格勒-纳塔催化剂进行了丙烯和乙烯无规共聚合的研究。对聚合温度、铝钛摩尔比、给电子体浓度和加氢等行为作了考察。共聚合速度和共聚物的比浓粘度呈规律性变化。用~(13)C-NMR和DSC测定了共聚物的组成、序列分布、熔点和结晶度.结果表明,在共聚合反应速度曲线上,在丙烯和乙烯分别为10mol%组成处,出现两个最大值。随共聚物中乙烯含量增加(2—10mol%),其熔点和结晶度降低,DSC峰变低、变宽,在乙烯含量达10mol%处出现双峰(128/116℃)反映出无规共聚链出现不同的序列分布。  相似文献   

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