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首页> 外文期刊>Journal of Applied Polymer Science >Diffusion-Limited Kinetics Modeling of One-Step Polyimide Formation
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Diffusion-Limited Kinetics Modeling of One-Step Polyimide Formation

机译：一步形成聚酰亚胺的扩散限制动力学模型

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摘要

A diffusion-limited kinetic model was developed to describe the imidization of one-step polythioetherimide formation based on an end group diffusion model. The changes of conversion and viscosity during the imidization were monitored with ther- mogravimetric analysis and dynamic stress rheometry, respectively. It was observed that the imidization rate began to decelerate after a fast early stage, whereas the viscosity in the system increased dramatically after a period oflow value. Amic acid and imide formations concurrently take place in the one-step polyimide formation, but the formation of amic acid is much slower than that of imide and is the rate-limiting step c>fimidization. When a second-order kinetic model was used to describe the imidization, the effect of viscosity on the diffusion resistance of reactive groups needed to be included. In order to predict the change of viscosity during the imidization, the Lip- shitz-Macosko model was modified and introduced into the diffusion-limited kinetic model by the Stokes-Einstein equation. The comparison of the modeled results with E!xperimental data indicated that the diffusion-limited kinetic model and the modified Lipshitz-Macosko model were able to efficiently predict the changes of conversion and Iliscosity with temperature and time during the one-step polythioetherimide formation.
机译：建立了扩散受限动力学模型，以描述基于端基扩散模型的一步聚硫醚酰亚胺形成的酰亚胺化。酰亚胺化过程中的转化率和粘度变化分别通过热重分析和动态应力流变法进行监测。观察到酰亚胺化速率在快速的早期阶段后开始降低，而体系中的粘度在一段低值时期后急剧增加。一步形成聚酰亚胺同时发生了酰胺酸和酰亚胺的形成，但酰胺酸的形成比酰亚胺的形成要慢得多，并且是限速步骤>酰胺化。当使用二阶动力学模型描述酰亚胺化时，需要考虑粘度对反应性基团扩散阻力的影响。为了预测酰亚胺化过程中的粘度变化，对Lipshitz-Macosko模型进行了修改，并通过Stokes-Einstein方程将其引入了扩散受限动力学模型。模型结果与实验数据的比较表明，扩散限制动力学模型和改进的Lipshitz-Macosko模型能够有效地预测一步式聚硫醚酰亚胺形成过程中转化率和粘度随温度和时间的变化。

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