The importance of mechanical recycling of polymers has increased within the last decades, especially due to numerous regulations of governments all over the world. Hereby recycling quotas are enforced to pave the way towards a closed loop recycling. During its lifetime, polymers are exposed to multiple environmental factors, which can already induce degradation. However, a major factor that needs to be taken into account is the increased thermo-mechanical stress during the recycling process, which may have significant impact on the quality of recyclates as well. In the present work, polyolefins (high-density polyethylene and polypropylene) were artificially exposed to stress by continuous extrusion at varying speeds and absence or presence of stabilizers to analyze the extent to which the recycling contributes to degradation processes. These samples were analyzed for low-molecular-weight stress markers by thermodesorption gas chromatography and by high-performance liquid chromatography (both coupled to mass spectrometric detection). Depending on the extent of stress, the occurrence of odd-numbered linear alkane chains was revealed in polyethylene samples, and of oxidized branched alkanes in polypropylene samples. Correlations with molecular weight (determined by high temperature gel permeation chromatography) and with decreasing concentrations of stabilizers could be demonstrated.

在过去的几十年里，聚合物机械回收的重要性有所增加，特别是由于世界各地政府的众多法规。因此，强制执行回收配额，为实现闭环回收铺平道路。在其生命周期中，聚合物会暴露于多种环境因素，这些因素已经可能导致降解。然而，需要考虑的一个主要因素是回收过程中增加的热机械应力，这也可能对回收物的质量产生重大影响。在目前的工作中，聚烯烃（高密度聚乙烯和聚丙烯）通过以不同速度和稳定剂存在或不存在的情况下连续挤出人为地暴露于应力，以分析回收对降解过程的影响程度。通过热解吸气相色谱和高效液相色谱（均与质谱检测联用）分析这些样品的低分子量应力标志物。根据应力的程度，聚乙烯样品中出现奇数直链烷烃，聚丙烯样品中出现氧化支链烷烃。可以证明与分子量（由高温凝胶渗透色谱法确定）和稳定剂浓度降低的相关性。在聚乙烯样品中发现了奇数直链烷烃链，在聚丙烯样品中发现了氧化支链烷烃。可以证明与分子量（由高温凝胶渗透色谱法确定）和稳定剂浓度降低的相关性。在聚乙烯样品中发现了奇数直链烷烃链，在聚丙烯样品中发现了氧化支链烷烃。可以证明与分子量（由高温凝胶渗透色谱法确定）和稳定剂浓度降低的相关性。