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首页> 外文期刊>Journal of Applied Polymer Science >Thermal behavior and kinetics during the stabilization of polyacrylonitrile precursor in inert gas
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Thermal behavior and kinetics during the stabilization of polyacrylonitrile precursor in inert gas

机译：惰性气体中聚丙烯腈前体稳定过程中的热行为和动力学

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摘要

The thermal behaviors of polyacrylonitrile precursor during thermal stabilization in inert gas were investigated by differential scanning calorimetry, thermomechanical analysis, and thermogravimetry. Combining these methods with the tracing of chemical changes by Fourier transform infrared spectroscopy indicated that complex reactions, including cyclization and pyrolytic reactions occurred sequentially. An imine-enamine tautomeric structure was formed at around 240°C and was converted to a conjugated structure when the temperature was increased to 400°C. A thermal stabilization mechanism was proposed and confirmed experimentally by using a two-step heating process. The apparent activation energies and the pre-exponential factors for these stabilization reactions were also estimated by the Kissinger, Ozawa, and "Improved Coats-Redfern" methods. To obtain a fit to the experiment data, a new kinetic model, named the "Three Regions Kinetic Model," was proposed using the Improved Coats-Redfern method. The applicability of this model and the prediction of the stabilization profile at a given heating rate were verified by plotting conversion rate against conversion profiles.
机译：通过差示扫描量热法，热力学分析和热重分析法研究了聚丙烯腈前体在惰性气体中热稳定过程中的热行为。将这些方法与通过傅立叶变换红外光谱法追踪化学变化相结合，表明复杂的反应（包括环化和热解反应）依次发生。亚胺-烯胺互变异构结构在约240°C形成，并在温度升高至400°C时转变为共轭结构。提出了一种热稳定机理，并通过两步加热工艺进行了实验验证。这些稳定化反应的表观活化能和指数前因子也通过Kissinger，Ozawa和“ Improved Coats-Redfern”方法进行了估算。为了适合实验数据，使用改进的Coats-Redfern方法提出了一个新的动力学模型，称为“三区域动力学模型”。通过将转化率对转化曲线作图，可以验证该模型的适用性以及在给定加热速率下稳定曲线的预测。

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