高分子合成与性能预测的计算机模拟

发布时间：2018-04-03 11:43

本文选题：共聚合反应　切入点：氯乙烯缺陷结构　出处：《河北工业大学》2004年硕士论文

【摘要】： 随着计算机技术的飞速发展，计算机与高分子科学之间的相互渗透已经成为高分子研究的又一亮点。计算机模拟既可预测分子结构行为和宏观物质性质，又可深化研究结果，提高工作效率。本文主要从四个方面研究了计算机在高分子科学上的应用，利用可视化程序语言Visual Basic 6.0编制了不同功能的软件。第一方面：利用计算机，通过截距斜率法、YBR法、JJ法(直线交叉法)、TM法(非线性最小二乘法)和动态搜索法测算共聚体系竞聚率，其中TM法和动态搜索法获得比较精确的竞聚率结果。由竞聚率的数据，，还给出共聚物组成曲线。利用计算机，通过共聚积分方程，描绘出共聚反应体系随着聚合转化率的变化，单体组成、共聚体瞬时组成和共聚体平均组成的关系曲线。此外，还对共聚物链段分布和链节分布情况进行了模拟，给出了它们的分布曲线。第二方面：用Monte Carlo法，模拟了聚氯乙烯缺陷结构的产生情况。模拟结果表明，过高的转化率必然导致形成更多的缺陷结构，使树脂品质下降。建议PVC生产厂家，氯乙烯的转化率以不超过0.85～0.87为宜。第三方面：利用热重分析法研究了聚合物的热分解动力学。先用三次样条函数对热失重数据进行了插值和微分，再通过二元回归求出了它的热分解动力学参数A、n及E，以上便是微商法的求解过程。它具有简洁、快速等优点。通过热分解动力学参数可以综合地、定量地表征聚合物的热稳定性，并且可确定热分解速率与温度之间的关系，给出热分解速率的峰值，对实际应用有指导意义。第四方面：基团贡献法为高分子新产品的开发研究提供了较好的辅助手段。利用高级编程语言Visual Basic语言编写的计算机软件，界面可视友好，使用方便，运算快速。此方法尤其适用于无定型聚合物，而对分子间具有较强作用力的聚合物，预测的误差较大。此外，由于该法仅提供了33种结构单元的有关参数，难以组合复杂结构的高分子，在使用范围上受到一定限制。第五方面：利用关联指数法对聚合物某些性能进行了预测，这些性能包括：摩尔体积，溶解度参数，表面张力，折光指数，介电常数及玻璃化转变温度等。本文在大量预测聚合物性能基础上，把预测值与实验值比较，采用相关系数和标准偏差评估了预测过程的精度。本文合成了新型的含氟聚酰亚胺，提出了预测这类聚酰亚胺玻璃化转变温度的回归方程。总的说来，关联指数法应用范围比基团贡献法广泛，对聚合物性能的预测精度也较高，但操作比较繁琐。
[Abstract]:With the rapid development of computer technology, the mutual penetration between computer and polymer science has become another bright spot in polymer research.Computer simulation can not only predict the molecular structure behavior and macroscopic material properties, but also deepen the research results and improve the working efficiency.In this paper, the application of computer in polymer science is studied from four aspects, and the software with different functions is programmed by the visual program language Visual Basic 6.0.On the one hand, using the computer, the reactivity rate of copolymerization system is calculated by means of intercept slope method and YBR method / JJ method (linear cross method / TM method) and dynamic search method.Among them, TM method and dynamic search method get more accurate results of reactivity rate.Based on the data of reactivity rate, the composition curve of copolymers was given.By using the computer and the integral equation of copolymerization, the relationship curves of the copolymerization reaction system with the polymerization conversion, the monomer composition, the instantaneous composition of the copolymerization and the average composition of the copolymer are described.In addition, the distribution of copolymers was simulated and their distribution curves were given.Second, Monte Carlo method is used to simulate the formation of PVC defect structure.The simulation results show that too high conversion will result in more defective structures and lower resin quality.It is suggested that the conversion rate of vinyl chloride should not exceed 0.85 or 0.87 for PVC manufacturers.Third, thermogravimetric analysis was used to study the thermal decomposition kinetics of polymers.The cubic spline function is first used to interpolate and differentiate the thermogravimetric data, and then the thermal decomposition kinetic parameters An and E are obtained by binary regression. The above is the process of solving the differential quotient method.It has the advantages of simplicity and speed.The thermal stability of the polymer can be quantitatively characterized by the kinetic parameters of thermal decomposition, and the relationship between the thermal decomposition rate and the temperature can be determined. The peak value of the thermal decomposition rate is given, which is of great significance for practical application.The fourth aspect: group contribution method provides a good auxiliary method for the development and research of new polymer products.The computer software written by Visual Basic language has the advantages of friendly interface, convenient use and fast operation.This method is especially suitable for amorphous polymers, and the prediction error is large for polymers with strong intermolecular forces.In addition, it is difficult to combine polymer with complex structure because only 33 kinds of structural elements are provided by the method, and the range of application is limited to a certain extent.Fifth, some properties of polymers were predicted by correlation index method, including molar volume, solubility parameters, surface tension, refractive index, dielectric constant and glass transition temperature.In this paper, based on a large number of predicted polymer properties, the accuracy of the prediction process is evaluated by using the correlation coefficient and standard deviation, comparing the predicted values with the experimental values.A new fluorinated polyimide was synthesized and a regression equation was proposed to predict the glass transition temperature of the polyimide.In general, the correlation index method is more widely used than the group contribution method, and the prediction accuracy of polymer properties is higher, but the operation is more complicated.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2004
【分类号】：O631

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