共查询到18条相似文献,搜索用时 93 毫秒
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本文讨论了A_(a_1),A_(a_2)-B_(b_1)B_(b_2)型缩聚反应的固化理论。给出了溶胶-凝胶分配公式、凝胶化条件、分布函数及适合固化全过程的高分子矩的循环公式和k次矩的解析表示式。 相似文献
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利用概率分析的方法研究了含引发机制的A2+Aa型缩聚反应体系的高分子矩,得到了高分子矩满足的递推公式,给出了该体系0次矩、1次矩和2次矩的明显表达式,讨论了高分子矩在凝胶点附近的临界表示式及其满足的标度律。 相似文献
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利用概率分析的方法研究了含引发机制的A2+Aα型缩聚反应体系的高分子矩,得到了高分子矩满足的递推公式,给出了该体系0次矩、1次矩和2次矩的明显表达式,讨论了高分子矩在凝胶点附近的临界表示式及其满足的标度律。 相似文献
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结合Aa-Bb,Cc型缩聚反应,给出了溶胶中含内环化的溶胶-凝胶分配公式及凝胶化条件。 相似文献
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唐敖庆 李泽生 孙家钟Institute of Theoretical Chemistry Department of Chemistry Jilin University Changchun 汤心颐Institute of Theoretical Chemistry Department of Chemistry Jilin University Changchun 《中国科学B辑(英文版)》1989,(9)
With monomer of A_aB_b type, the polymer moments of polycondensation reaction is inves-tigated in detail by means of direct differentiation technique to obtain a recursion formula.This formula is suitable for both pre-gel and post-gel in evaluating the polymer momentsexplicitly. 相似文献
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《Computational and Theoretical Polymer Science》2001,11(2):113-127
The spanning-tree approximation model is one of the models used for polymerizations with intramolecular reaction regardless of the size of the ring formed. We present a modification of this model that uses more accurate internal estimates of the probabilities of intramolecular reaction. This requires limited Monte Carlo simulations of some molecular structures, resulting in a hybrid probability model (a combined analytic and Monte Carlo model). We then extend the spanning-tree model so that it may be used in the post-gel region. We show three possible extensions of varying degrees of complexity. The resulting models for stepwise Af homopolymerizations have been coded into programs that run on desktop PCs in a few seconds. The models calculate the amount of intramolecular conversion, the weight-average molecular weight, the gel point, the weight fraction of soluble material, and the weight-average molecular weight of the sol fraction. We discuss the relative merits of the modified spanning-tree model and its three post-gel extensions and show sample calculations for arbitrary homopolymerization systems. 相似文献
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ThetheoryofnonlinearpolymerizationwasinitiatedbyFlory[1]andStockmayer[2].Forsimplifyingtheevaluationofaveragepolymerquantities,manyotherstatisticalmethodssuchastheprobabilityofgeneratingfunctionmethod[3],thelawoftotalprobabilitymethod[4,5]andtheothermethods[6… 相似文献
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With monomer of A_aB_b type, the sol fraction of polycondensation for post-gel, in whichnot only the functional groups of A to react with those of B, but also the functional groupsof A with those of A and the functional groups of B with those of B are involved, is discuss-ed in detail. As a direct result, the gelation condition is obtained explicitly. 相似文献
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用唐敖庆等曾得到的含内环化A_a-B_b型缩聚反应的固化理论,对配料比为1.3的己二酸-三羟甲基丙烷缩聚反应实验数据进行了分析,得到的溶胶-凝胶分配曲线与实验结果符合的较好,进一步讨论了内环化对凝胶点的影响,算出了凝胶点以上数均、重均和Z均分子量的理论曲线. 相似文献
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《European Polymer Journal》1985,21(7):611-617
The molecular parameters characterizing the post-gel properties of macromolecular networks made by chainwise polymerization of polyfunctional monomers are established from the determination of the finite chain probability, computed directly from very simple implicit equations. Thus, sol fraction, crosslink density, effective network chains numbers, dangling trees numbers, and cycle rank are derived easily in very general systems and have expressions morphologically analogous as those obtained for the stepwise polyfunctional polymerization. 相似文献
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Ze-sheng Li Xin-wu Ba Chia-chung Sun Au-chin Tang 《Macromolecular theory and simulations》1992,1(2):91-97
For a polycondensation reaction with identical structural units AaBb (i.e. each unit has a functional groups of type A and b of type B) the kth radius of gyration $ \begin{array}{*{20}c} {\left\langle {R^2 } \right\rangle _k = \sum\limits_n {n^k \cdot \left\langle {R_n^2 } \right\rangle P_n } } & {({\rm sum over all }n{\rm - mers; see Eqs}{\rm . (11) and (17))}{\rm }} \\ \end{array} $ is investigated. By means of a differential method, a recursion formula that holds true for both the pre-gel and the post-gel state is obtained for the evaluation of the kth radius. 相似文献