An in depth understanding of the kinetics of the decomposition of plastic mixtures is necessary to enhance chemical recycling approaches, in particular by pyrolysis. The fact that plastic waste is usually composed of mixtures of plastics constitutes a hindrance for secondary recycling but may not be a particular difficulty for tertiary recycling. In this study, an analysis of the thermal degradation of mixtures of high‐density polyethylene (HDPE) and polypropylene (PP), in different proportions, was carried‐out under pyrolysis conditions using thermogravimetric analysis (TGA) under nonisothermal conditions, at different heating rates. Both isoconversional and model‐fitting approaches were used to estimate kinetic parameters from the experimental information. It was found that both the degradation of HDPE and PP, as well as their mixtures, can be described by a single‐step degradation process but that the degradation process is influenced by the proportion between the two plastics. The HDPE/PP mixtures in which PP has a higher ratio than HDPE cause the degradation onset temperature for the mixture to be lower than either pure PP or pure HDPE. Also, it was found that the apparent activation energy estimated was lower for these mixtures in comparison with the pure polymers. This implies that there are extensive interactions between the plastics during the degradation procedure and, from an operational point of view, it may be actually easier to degrade plastic mixtures than the corresponding pure streams, a conclusion that is important in the context of tertiary recycling of plastic mixtures. Furthermore, it was observed that a compensation effect exists that encompasses all the kinetic data for the mixtures, regardless of the composition, indicating that, although significant changes occur in relation to the activation energy, the underlying degradation mechanism remains the same.

中文翻译：

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HDPE + PP聚合物混合物降解的动力学分析

必须深入了解塑料混合物的分解动力学，以增强化学回收方法，特别是通过热解的方法。塑料废料通常由塑料混合物组成的事实构成了二次回收的障碍，但对于三次回收来说并不是特别困难。在这项研究中，在热解条件下，使用热重分析（TGA）在非等温条件下，在不同加热条件下，对不同密度的高密度聚乙烯（HDPE）和聚丙烯（PP）混合物的热降解进行了分析。费率。同转化方法和模型拟合方法均用于根据实验信息估算动力学参数。发现HDPE和PP及其混合物的降解，可以通过单步降解过程来描述，但是降解过程受两种塑料之间的比例影响。PP具有比HDPE高的比例的HDPE / PP混合物导致混合物的降解起始温度低于纯PP或纯HDPE。另外，发现与纯聚合物相比，这些混合物的表观活化能估计较低。这意味着在降解过程中，塑料之间存在广泛的相互作用，从操作的角度来看，与相应的纯物流相比，降解塑料混合物实际上可能更容易，这一结论在三氯甲烷的三次循环中非常重要。塑料混合物。此外，