共查询到18条相似文献,搜索用时 218 毫秒
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根据共聚物组成的计算方法,合成了组成均匀的端羟基丁二烯与丙烯腈液体共聚物并用NMR观察和计算了该液体聚合物的序列分布,测定了力学性能。 相似文献
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通过分批聚合,制备具有均匀组成的共聚物。提出了为控制共聚物组成在反应过程中补加单体的计算方法。它不仅适用于丁二烯与丙烯腈的共低聚反应,也适用于其它二元共低聚反应 相似文献
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通过分批聚合,制备具有均匀组成的共聚物,提出了为控制共聚物组成在反应过程中补加单体的计算方法。它不仅适用于二烯与丙烯腈的共低聚反应,也适用于其它二元共低聚反应。 相似文献
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计算机辅助有机元素分析研究共聚物的组成 总被引:1,自引:0,他引:1
本文提出了计算机辅助有机元素分析计算高分子共聚物组成的一般公式,并以丙烯酰胺-丙烯酸钠共聚物为例予以验证。同时测试了AP-20系列共聚物及AT-430共聚物的共聚组成,其结果与~(13)C NMR测定数据一致。 相似文献
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本文将稀土络合物Nd(P204)3、Nd(P507)3、Nd(naPh)3、Nd(acac)3.3H2O与烷基铝组成的二元体系催化剂用于共聚马来酸酐(MAn)与环氧丙烷(PO)获得成功.并采用1H—NMR研究了共聚物三元组序列分布.结果表明,稀土络合催化剂为MAn与PO共聚的优良催化刑,可得到高转化率、高交替度共聚物.共聚物数均分子量Mn和分子量分布分别为2000—3000、1.3—1.7,共聚物中MAn的摩尔含量40%以上.共聚物组成及序列分布与投料比、催化剂种类、溶剂性质等有关.理论计算表明,序列分布符合三级马尔可夫(Markoffian)过程. 相似文献
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四氟乙烯/偏氟乙烯乳液共聚反应的竞聚率测定 总被引:3,自引:0,他引:3
用亨利定律关联了四氟乙烯 (TFE) /偏氟乙烯 (VDF)乳液共聚合体系中的单体气相分压与其对应液相浓度间的关系 ,推导了用气相摩尔分数表示的共聚物组成方程式 .通过气相色谱和19F NMR分别测定了共聚反应前后气相单体组成和共聚物组成 ,用非线性回归法 (RREVM )计算TFE/VDF乳液共聚合反应表观竞聚率分别为γTFE=0 35和γVDF=0 6 3 .将实测的表观竞聚率代入共聚物组成方程计算共聚物组成与由19F NMR测定的结果一致 ,为进一步的工业放大试验提供科学依据 相似文献
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Radical copolymerization of sulfur dioxide and vinyl chloride (VC) has been studied by the comparison of the composition of copolymers obtaining from different reaction conditions, i.e., reaction temperatures, feed compositions, and total monomer concentrations. The composition of VC in copolymer is independent of comonomer composition except at high concentration of VC in feed; it increases with increasing reaction temperature or decreasing total monomer concentration. At lower temperature, the composition of copolymer becomes independent of total monomer concentration. The overall rate of polymerization is proportional to [VC]1,7 and [SO2]0.5. These results were compared with those obtained in our previous study on the SO2-styrene copolymerization. A propagation mechanism for radical copolymerization of SO2 and VC is also proposed. 相似文献
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F. L. M. Hautus H. N. Linssen A. L. German 《Journal of polymer science. Part A, Polymer chemistry》1984,22(12):3661-3671
Two calculation methods for estimating reactivity ratios, one method based on the differential Alfrey-Mayo equation and one based on the integrated form of this model, are compared with respect to precision and bias. Both methods are characterized by the use of information about the monomer feed composition only and are assumed to be valid up to high conversion. As only monomer feed composition has to be analyzed, several sampling designs are feasible. Two extreme designs can be distinguished. One consists of repetitive sampling of the initial and final monomer feed mixture, whereas the other consists of sequential sampling during the course of the reaction. The influence of both designs of the calculated r-values is investigated by means of simulation. In the present paper the second calculation method, based on the integrated form, is solved by a nonlinear least squares method considering errors in both variables. This method required additional information about the errorstructure of the data. As this information is mostly of approximate nature, the influence of misspecification of this error structure on the calculated r-values is also examined. 相似文献
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Gregory Kharas David H. Kohn 《Journal of polymer science. Part A, Polymer chemistry》1983,21(5):1457-1473
Trisubstituted ethylene, ethyl α-cyanocinnamate, is readily copolymerized with vinyl acetate by a conventional radical initiator. Terminal, penultimate, and “complex” copolymerization models were applied by using the data of composition of the copolymers obtained in bulk and by copolymerization in benzene, ethyl acetate, and chloroform. The model based on the participation of the monomer complexes describes satisfactorily the deviation from the terminal copolymerization model. The proton NMR analyses of the monomer mixtures indicate that the interaction between the monomers leads to the formation of weak monomer complexes. Kinetic studies of the initial rate dependence on the total monomer concentration and monomer feed composition enabled us to evaluate the degree of participation of the free uncomplexed monomers and the monomer complex in the propagation reactions. The contribution of the complexed monomers in the propagation stages increases with the increase in total monomer concentration. The initial rate of the copolymerization is proportional to the square root of the initiator concentration, thus confirming the bimolecular termination of the macrochains. The rate constants of the addition reactions of the complex and free monomers were evaluated from the kinetic studies. The quantitative kinetic treatment provided information regarding the relative weight of the termination reaction and indicated that the termination in the system occurs predominantly by the cross-termination reaction between two growing polymer radicals with different kinds of monomer units at the ends. Additional information on the termination in this system was obtained from viscosity measurements. 相似文献
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The applicability of the method of Giese to the measurement of the influence of monomer reactivity is examined. The reaction of alkyl mercuric salts with sodium borohydride permits the production of alkyl (cyclohexyl and butyl) radicals. Since hydrogen radicals are present in high concentration, the addition of alkenes to the reaction mixture leads to radicals from the alkenes. Further addition of alkene (polymerization) can be nearly completely excluded in this way. The composition of the reaction products is determined by gas chromatography. The addition rate of the alkenes relative to styrene allows correlation with the e value of the Q-e scheme of Alfrey and Price. The method answers the question of how far addition of the monomer complex occurs in one step or as separate addition of both monomers during copolymerization in the presence of charge-transfer (CT) complexes of the monomers. The investigations are performed by using the styrene/acrylonitrile/ZnCl2system, and it is demonstrated that the reactivity of the complexed 相似文献
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聚甲基丙烯酸甲酯型高分子染料的合成 总被引:2,自引:0,他引:2
高分子染料的合成研究起于60年代初[1].1973年,Marechal等实现了无色高分子材料与有色染料分子的化学键合[2~3].目前,高分子染料已广泛应用于化妆品、涂料、填料、食品等领域并开始探索在液晶显示、半导体材料、激光记录、非线性光学材料、亲和... 相似文献
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David P. Mobley 《Journal of polymer science. Part A, Polymer chemistry》1984,22(11):3203-3215
Reaction rate measurements show that a Michaelis-Menten model proposed earlier is inadequate to describe the full course of the polymerization of 2,6-dimethylphenol to poly(2,6-dimethyl-1,4-phenylene oxide). Modification of this model to include the effects of catalyst deactivation during the reaction and difference in reactivity between the monomer and other oligomers resulted in much greater accuracy. The kinetic constants in the modified model were influenced by reaction temperature, system composition, and method of catalyst component addition. 相似文献
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Lilian F. J. Noël Jan M. A. M. Van Zon Ian A. Maxwell Anton L. German 《Journal of polymer science. Part A, Polymer chemistry》1994,32(6):1009-1026
Monomer partitioning in emulsion copolymerization plays a key role in determining composition drift and polymerization rates. The combination of recently developed thermodynamically based monomer partitioning relationships with mass balance equations, makes predictions of monomer partitioning in emulsion copolymerizations possible in terms of monomer mole fractions and monomer concentrations in the particle and aqueous phases. Using this approach, the effects of monomer to water ratios and polymer volumes on the monomer mole fraction within the polymer particle phase in a nonpolymerizing system at thermodynamic equilibrium can be determined. Comparison of these monomer partitioning predictions with experiments for the monomer system methyl acrylate—vinyl acetate shows good agreement. Furthermore, composition drift occurring in a polymerizing system as a function of conversion can be predicted if the assumption is made that equilibrium is maintained during reaction. Comparison of predictions with experimental results for emulsion copolymerizations of the monomer systems methyl acrylate—vinyl acetate and methyl acrylate—indene shows good agreement. © 1994 John Wiley & Sons, Inc. 相似文献