Insights into the carbonization mechanism of PAN-derived carbon precursor fibers and establishment of a kinetics-driven accelerated reaction template for atomistic simulation.
Insights into the carbonization mechanism of PAN-derived carbon precursor fibers and establishment of a kinetics-driven accelerated reaction template for atomistic simulation.
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DOI：
10.1039/d2cp05196f
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发表时间：
2023-05
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通讯作者：
Pengcheng Shi;Yingdan Zhu;Haibing Xu;Chun Yan;Dong Liu;L. Yue;Gang Chen
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作者：
Pengcheng Shi;Yingdan Zhu;Haibing Xu;Chun Yan;Dong Liu;L. Yue;Gang Chen
为了更好地理解聚丙烯腈（PAN）基前体纤维碳化过程背后的化学过程，并为工艺优化和合理的性能设计提供更真实的工艺继承模型的虚拟对应物，我们开发了一次废气产物的箭头推进反应路线，（H2O/H2/HCN/N2/焦油蒸气）的形成和实用动力学-驱动的加速反应模板，用于碳化过程的原子模拟，克服了传统的时间尺度差异的挑战，反应扩散系统混合第一性原理计算的焓垒结果验证了两段碳化过程中碳化反应的合理性和顺序性。根据Eyring过渡态理论，实现了反应程度的动力学等效，估算了300 s炭化过程中各速控步骤的转化率。过程控制测量进一步证明对应于所提出的机制。在拓扑反应分子动力学模板中植入了专门为表面层设计的迭代致密化交联方案，成功预测了从预氧化纤维到原始碳纤维表面整个演化过程中一系列高度可设计的结构模型。该模型的最终结构与II型高强度碳纤维表面在碳产率和元素组成方面具有极好的相似性。
To better understand the chemistry behind the carbonization process of the polyacrylonitrile (PAN)-based precursor fibers and provide a more authentic virtual counterpart of the process-inherited model for process optimization and rational performance design, we develop arrow-pushing reaction routes for primary exhaust gas product (H2O/H2/HCN/N2/tar vapor) formation and a pragmatic kinetics-driven accelerated reaction template for atomistic simulation of the carbonization process overcoming traditional challenges in time scale discrepancy of the reaction-diffusion system. The results of enthalpy barriers from hybrid first principles calculations validate the rationality and sequence of conjectured reactions during the two-stage carbonization process. Conversion rates of the rate-determining steps under 300 s carbonization are also estimated based on Eyring's transition state theory realizing kinetics equivalency of the reaction extent. Process-control measurements are further demonstrated corresponding to the proposed mechanism. The iterative densified crosslinking scheme specially designed for the surface layer is implanted into the topological reaction molecular dynamics template and a series of highly devisable structural models during the whole evolutionary process from the pre-oxidized fiber to the pristine carbon fiber surface are successfully predicted. The ultimate structure of the model presents excellent similarity in carbon yield and elemental composition with the type II high strength carbon fiber surface.