The incorporation of natural fibers, represented by cellulose fibers, into functional composites for construction applications has garnered widespread attention due to their renewability and sustainability. However, their flammability raises concerns around fire safety. To investigate further the combustion mechanism and kinetics of cellulose, molecular dynamics simulations equipped with reactive forcefield (ReaxFF) are conducted on active cellulose polymers. High-temperature ReaxFF simulations are characterized by effective collisions that better approximate reality. The detailed reaction scheme revealed by the simulations is consistent with the experimental results. The formation of main combustion products, such as carbon monoxide, carbon dioxide, and water, highly depends on free radical reactions. Toxic species such as formaldehyde, glycolaldehyde, and carbon monoxide can be inhibited through effective control of hydroxymethyl, acetyl, and formyl radicals. A higher effective collision proportion promotes combustion, mainly through the enhanced activity of free radicals such as hydroxyl groups. Besides, increased oxygen coefficients have a negligible effect on the final combustion products under oxygen-rich conditions, although intermediates show noticeable sensitivity to oxygen. A kinetic analysis of the initial decomposition and intermediate reaction stages of cellulose combustion is presented, yielding reaction rates consistent with first-order reaction kinetics. This study provides atomic-level insights into cellulose combustion and lays a foundation for predicting the detailed combustion chemistry of cellulose-based materials, which can inform a material design aimed at better fire resistance.

中文翻译：

---

通过 ReaxFF 分子动力学模拟探索纤维素燃烧的反应机制和动力学


将以纤维素纤维为代表的天然纤维纳入建筑应用的功能复合材料中，由于其可再生性和可持续性而受到广泛关注。然而，它们的易燃性引起了人们对消防安全的担忧。为了进一步研究纤维素的燃烧机制和动力学，对活性纤维素聚合物进行了配备反应力场（ReaxFF）的分子动力学模拟。高温 ReaxFF 模拟的特点是有效碰撞，更接近现实。模拟揭示的详细反应方案与实验结果一致。主要燃烧产物（例如一氧化碳、二氧化碳和水）的形成高度依赖于自由基反应。通过有效控制羟甲基、乙酰基和甲酰基自由基，可以抑制甲醛、乙醇醛和一氧化碳等有毒物质。较高的有效碰撞比例促进燃烧，主要是通过增强羟基等自由基的活性。此外，尽管中间体对氧表现出明显的敏感性，但在富氧条件下，增加的氧系数对最终燃烧产物的影响可以忽略不计。对纤维素燃烧的初始分解和中间反应阶段进行了动力学分析，得出的反应速率与一级反应动力学一致。这项研究提供了对纤维素燃烧的原子级见解，并为预测纤维素基材料的详细燃烧化学奠定了基础，这可以为旨在提高耐火性的材料设计提供信息。