Understanding the combustion behavior of rubbers is crucial for predicting their fire hazards. The cone calorimeter experimental results in this study confirm that the combustion behavior of raw rubbers depends on the rubber type and the heat flux. Natural rubber and ethylene-propylene-diene monomer rubber exhibit heat release rate (HRR) curves with only one peak at the end of the burning stage under all tested heat fluxes. At higher heat fluxes, the HRR curves of polybutadiene rubber (BR) and styrene butadiene rubber (SBR) exhibit a single peak; at heat fluxes lower than 20 kWm, two HRR peaks were observed. The proposed mechanism model with the crosslink reaction as the key factor can explain the emergence of two-peak HRR curve and has been proved through experiments and simulations. For BR and SBR at 15 kWm, the specimens exhibit two upper layers at ignition time. The surface pyrolysis layer seems to be covered by black film or char, with the crosslink degree as high as 84.23–100 %. The second crosslink reaction layer exhibits a higher decomposition temperature than the original rubber. Based on reaction kinetics and thermodynamics data derived from TG/DSC experiments, the novel pyrolysis model taking crosslink reaction and thermal decomposition of crosslinked intermediate into account well predicts the HRR curves obtained at varied heat fluxes. The conversion of raw rubber to the crosslinked intermediate plays an important role in the reduction of HRR immediately after ignition, resulting in the first HRR peak.

中文翻译：

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辐射热通量对生胶燃烧行为的影响机理

了解橡胶的燃烧行为对于预测其火灾危险至关重要。本研究中的锥形量热仪实验结果证实，生橡胶的燃烧行为取决于橡胶类型和热通量。在所有测试的热通量下，天然橡胶和三元乙丙橡胶的放热率（HRR）曲线仅在燃烧阶段结束时出现一个峰值。在较高热通量下，聚丁二烯橡胶（BR）和丁苯橡胶（SBR）的HRR曲线呈现单峰；在热通量低于 20 kWm 时，观察到两个 HRR 峰值。所提出的以交联反应为关键因素的机理模型可以解释双峰HRR曲线的出现，并已通过实验和模拟得到证明。对于 15 kWm 的 BR 和 SBR，样品在点火时呈现出两个上层。表面热解层似乎被黑色薄膜或炭覆盖，交联度高达84.23-100%。第二交联反应层表现出比原始橡胶更高的分解温度。基于TG/DSC实验的反应动力学和热力学数据，考虑交联反应和交联中间体热分解的新型热解模型很好地预测了在不同热通量下获得的HRR曲线。生胶向交联中间体的转化对于点燃后 HRR 的立即降低起着重要作用，从而产生第一个 HRR 峰。