Frigione Mariaenrica, Rodríguez-Prieto Alvaro
Department of Engineering for Innovation, University of Salento, Prov. le Lecce-Monteroni, 73100 Lecce, Italy.
Department of Manufacturing Engineering, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
Polymers (Basel). 2021 Aug 12;13(16):2688. doi: 10.3390/polym13162688.
During their useful life, polymers are subject to degradation processes due to exposure to specific environmental conditions over long times. These processes generally lead to changes, almost always irreversible, of properties and performances of polymers, changes which would be useful to be able to predict in advance. To meet this need, numerous investigations have been focused on the possibility to predict the long-term performance of polymers, if exposed to specific environments, by the so called "accelerated aging" tests. In such procedures, the long-term behavior of polymeric materials is typically predicted by subjecting them to cycles of radiations, temperatures, vapor condensation, and other external agents, at levels well above those found in true conditions in order to accelerate the degradation of polymers: this can produce effects that substantially deviate from those observable under natural exposure. Even following the standard codes, different environmental parameters are often used in the diverse studies, making it difficult to compare different investigations. The correlation of results from accelerated procedures with data collected after natural exposure is still a debated matter. Furthermore, since the environmental conditions are a function of the season and the geographical position, and are also characteristic of the type of exposure area, the environmental parameters to be used in accelerated aging tests should also consider these variables. These and other issues concerning accelerated aging tests applied to polymers are analyzed in the present work. However, bearing in mind the limitations of these practices, they can find useful applications for rating the durability of polymeric materials.
在其使用期限内，聚合物由于长时间暴露于特定环境条件下而会经历降解过程。这些过程通常会导致聚合物的性能和表现发生变化，而且几乎总是不可逆转的，这些变化若能提前预测将会很有帮助。为满足这一需求，众多研究聚焦于通过所谓的“加速老化”试验来预测聚合物在特定环境下的长期性能的可能性。在这类试验程序中，通常通过使聚合物材料经受辐射、温度、蒸汽冷凝及其他外部因素的循环作用来预测其长期行为，这些作用的强度远高于实际条件下的强度，以便加速聚合物的降解：这可能会产生与自然暴露下可观察到的效果有很大偏差的结果。即使遵循标准规范，不同研究中也常常使用不同的环境参数，这使得不同研究之间难以进行比较。加速试验结果与自然暴露后收集的数据之间的相关性仍是一个有争议的问题。此外，由于环境条件是季节和地理位置的函数，也是暴露区域类型的特征，加速老化试验中使用的环境参数也应考虑这些变量。本文分析了与应用于聚合物的加速老化试验相关的这些及其他问题。然而，考虑到这些做法的局限性，它们在评定聚合物材料耐久性方面仍可找到有用的应用。
