Abstract Poly(bisphenol A carbonate) or polycarbonate (PC) constitutes a significant fraction of the Waste Electrical and Electronic Equipment, mainly due to its high production and consumption rate and its variety of applications. Traditional methods for its treatment no longer appear to provide long-term solutions and for this reason, the investigation of thermochemical methods and more specifically pyrolysis as a potential recycling method took place in the current study. In the first part of this study, pyrolysis studies of polycarbonate have been performed in a Pyrolizer equipped with GC–MS, at five different reactor temperatures, in order to facilitate the understanding of the degradation mechanism. Higher pyrolysis temperatures were found to be more suitable for PC pyrolysis, since they increased the volatile fractions (liquid and gaseous). The gaseous fraction consisted mainly of CO2, CH4 and CO, whereas in the liquid fraction a large amount of different phenolic compounds, including the monomer bisphenol A was recorded. Based on the findings, it has been suggested that the main degradation pathway follows a chain scission mechanism and that the scission of the isopropylidene linkage is the first step. Phenols and phenolic compounds were formed through a series of scission and hydrolysis reactions. In the second part, pyrolysis kinetics of PC are investigated in detail using thermogravimetric experimental data, collected at several heating rates and several either model-free (isoconversional) or model-fitting models. From the isoconversional kinetic analysis the effective activation energy was fund to increase with the extent of conversion, ranging from 146 to 189 kJ/mol and from 154 to 215 kJ/mol, when using the integral method of Tang (similar to the KAS) or the differential method of Friedman, respectively. A simple first order kinetic model was found to simulate excellent the experimental data, though predicting different activation energies and pre-exponential factors at each heating rate employed. The random scission and the autocatalytic models were investigated in detail and the best fit to the experimental data at all different heating rates was found to be the autocatalytic model with n = 1.15 and m = 0.46 (values close to those considered for the random scission model with L = 2, i.e. n = 1.119 and m = 0.4) using an average activation energy, E = 195.9 kJ/mol and pre-exponential factor A = 6.06 1012 min−1. Having a detailed knowledge of the PC degradation kinetics and mechanism will help in better design of large scale process for the recycling of such material originating in WEEE and provide targeted value-added products.

中文翻译：

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废弃电子电器设备中聚（双酚A碳酸酯）基聚合物的热解机理和热降解动力学

摘要 聚（双酚A碳酸酯）或聚碳酸酯（PC）构成了废弃电子电气设备的重要组成部分，主要是由于其生产和消耗率高且应用广泛。传统的处理方法似乎不再提供长期解决方案，因此，在当前的研究中进行了热化学方法的研究，更具体地说，热解是一种潜在的回收方法。在本研究的第一部分，聚碳酸酯的热解研究在配备 GC-MS 的热解器中在五种不同的反应器温度下进行，以促进对降解机制的理解。发现较高的热解温度更适合 PC 热解，因为它们增加了挥发性部分（液体和气体）。气体部分主要由 CO2、CH4 和 CO 组成，而在液体部分记录了大量不同的酚类化合物，包括单体双酚 A。基于这些发现，有人提出主要的降解途径遵循断链机制，而异亚丙基键的断裂是第一步。酚类和酚类化合物是通过一系列裂解和水解反应形成的。在第二部分中，使用热重实验数据详细研究了 PC 的热解动力学，这些数据以多种加热速率和几种无模型（等转化）或模型拟合模型收集。从等转化动力学分析，有效活化能随着转化程度的增加而增加，当分别使用 Tang 积分法（类似于 KAS）或 Friedman 微分法时，分别为 146 至 189 kJ/mol 和 154 至 215 kJ/mol。发现一个简单的一级动力学模型可以模拟出色的实验数据，尽管在采用的每个加热速率下预测不同的活化能和指前因子。对随机切割和自催化模型进行了详细研究，发现最适合所有不同加热速率下的实验数据的是具有 n = 1.15 和 m = 0.46 的自催化模型（值接近于随机切割模型所考虑的值） L = 2，即 n = 1.119 和 m = 0.4) 使用平均活化能，E = 195.9 kJ/mol 和指数前因子 A = 6.06 1012 min−1。