A concise kinetic model catering for the antioxidant reaction of thermally aged cross-linked polyethylene (XLPE) cable insulation before its abrupt performance deterioration is proposed for life prediction and condition assessment. The alternating current breakdown strength, elongation at break, carbonyl index, and pyrolysis activation energy of XLPE insulation are found to consistently display an abrupt change at a certain point of ageing time. This is strongly correlated to the depletion of the antioxidant whose content gradually decreases with ageing time and drops to a critical value, after which the abrupt degradation of the above macroscopic performances happens. Based on the simplified chain reactions of XLPE during thermal-oxidative ageing, a concise kinetic model about antioxidant prediction is accordingly established by solving the chemical kinetics equations. It indicates that the antioxidant content decays with the reciprocal of time before the abrupt degradation occurs. Results of antioxidant content predicted by the kinetic model at different temperatures matches well with the experimental results, and its reliability can also be proved by the Arrhenius relationship of the obtained results. The kinetic model proposed herein demonstrates satisfying conciseness and thus can be highly feasible in ageing condition assessment and life predicting of XLPE insulation.

中文翻译：

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抗氧化剂消耗动力学模型与交联聚乙烯电缆绝缘老化行为的相关性

针对热老化交联聚乙烯 (XLPE) 电缆绝缘在其性能突然恶化之前的抗氧化反应提出了一个简明的动力学模型，用于寿命预测和状态评估。研究发现，XLPE 绝缘材料的交流电击穿强度、断裂伸长率、羰基指数和热解活化能在特定的老化时间点始终显示出突然变化。这与抗氧化剂的消耗密切相关，抗氧化剂的含量随着老化时间逐渐降低并下降到临界值，之后发生上述宏观性能的突然下降。基于 XLPE 在热氧化老化过程中的简化链反应，通过求解化学动力学方程，建立了简明的抗氧化预测动力学模型。这表明在突然降解发生之前，抗氧化剂含量随时间的倒数衰减。不同温度下动力学模型预测的抗氧化剂含量结果与实验结果吻合较好，所得结果的Arrhenius关系也证明了其可靠性。本文提出的动力学模型表现出令人满意的简洁性，因此在 XLPE 绝缘的老化条件评估和寿命预测中具有高度的可行性。不同温度下动力学模型预测的抗氧化剂含量结果与实验结果吻合较好，所得结果的Arrhenius关系也证明了其可靠性。本文提出的动力学模型表现出令人满意的简洁性，因此在 XLPE 绝缘的老化条件评估和寿命预测中具有高度的可行性。不同温度下动力学模型预测的抗氧化剂含量结果与实验结果吻合较好，所得结果的Arrhenius关系也证明了其可靠性。本文提出的动力学模型表现出令人满意的简洁性，因此在 XLPE 绝缘的老化条件评估和寿命预测中具有高度的可行性。