Without knowledge and resultful surveillance of the early degradation of polymers, it is challenging to realize the high reliability of high-end equipment and the screening and grading of waste plastics. Their reliability evaluation and lifetime prediction are also unfulfillable for a lack of sensitive characterization techniques. This work, taking commercial ethylene propylene diene monomer (EPDM) composite as an example, explores a variety of multi-scale evaluation methods to identify its early thermal aging behaviors and molecular mechanisms, including various spectroscopic technology, swelling-equilibrium tests, scanning electron microscope (SEM), thermal analysis, contact angle tests and mechanical properties. Only some methods can give the perceptible indicators of the slight thermal degraded EPDM, namely fluorescent probe technology, infrared spectroscopy for gas mixtures, swelling-equilibrium tests and specific mechanical properties. Other methods are inferior in early aging identification. Both fluorescent probe technology and infrared spectroscopy for gas mixtures can recognize the thermal degradation induced products within 5 h at a temperature lower than 120 °C, while elongation at break can reflect the damage of EPDM within 5 h at 60 °C. Based on the time-temperature superposition principle, the master curve of the thermal aged EPDM is constructed using the data of elongation at break, which predicts that 50% retention of elongation at break occurs after 10.5 years at 30 °C. We further propose a new aging evaluation methodology to reflect the aging degree comprehensively, which is based on the standardized sequence numbers obtained from the above sensitive characterization methods.

中文翻译：

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监测和评估 EPDM 复合材料早期难以察觉的热降解的系统方法

如果没有对聚合物早期降解的了解和有效的监测，实现高端设备的高可靠性以及废塑料的筛选和分级是一项挑战。由于缺乏灵敏的表征技术，它们的可靠性评估和寿命预测也无法实现。这项工作以商业三元乙丙橡胶复合材料为例，探索了多种多尺度评价方法来鉴定其早期热老化行为和分子机制，包括各种光谱技术、溶胀平衡测试、扫描电子显微镜(SEM)、热分析、接触角测试和机械性能。只有一些方法可以给出轻微热降解EPDM的可感知指标，即荧光探针技术、气体混合物红外光谱、溶胀平衡测试和特定机械性能。其他方法在早期老化识别方面效果较差。气体混合物的荧光探针技术和红外光谱都可以识别低于120℃的温度下5小时内的热降解诱导产物，而断裂伸长率可以反映EPDM在60℃下5小时内的损坏情况。基于时间-温度叠加原理，利用断裂伸长率数据构建热老化EPDM主曲线，预测30℃下10.5年后断裂伸长率保持50%。我们进一步提出了一种新的老化评估方法来全面反映老化程度，该方法基于从上述敏感表征方法获得的标准化序列号。