Kinetics of the low-temperature pyrolysis of polyethene, polypropene and polystyrene modeling, experimental determination and comparison with literature models and data
Kinetics of the low-temperature pyrolysis of polyethene, polypropene and polystyrene modeling, experimental determination and comparison with literature models and data
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DOI：
10.1021/ie960501m
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发表时间：
1997-06
影响因子：
4.2
通讯作者：
Rwj Westerhout;J. Waanders;J. Kuipers;V. Swaaij
中科院分区：
文献类型：
--
作者：
Rwj Westerhout;J. Waanders;J. Kuipers;V. Swaaij
在低于450 ℃的温度下研究了低密度聚乙烯、高密度聚乙烯、聚丙烯和聚苯乙烯的热解动力学。此外，对这些聚合物的低温热解的文献综述已经进行，并已显示，在所报道的动力学数据的分散是显着的，这是最有可能是由于使用简单的一阶动力学模型来解释实验数据。此模型类型仅适用于较小的转换范围，但许多作者在更宽的转换范围内使用。在本研究中，通过进行等温热重分析（TGA）实验，在低于450 ℃的温度下研究了上述聚合物和聚合物混合物的热解动力学。TGA实验数据用于确定动力学参数的基础上，一个简单的一阶模型的高转化率（70-90%）和本研究中开发的模型，称为随机链解离（RCD）模型，为整个转化率范围。用RCD模型研究了分子量、支化度和断裂度等重要参数对热解动力学的影响。该模型还被用来计算热解过程的初级产物谱。实验研究了支化度和初始分子量对热解过程的影响。发现支化程度的影响是相当显著的，但初始分子量的影响是次要的。这些结果被认为是同意相当不错，从RCD模型得到的预测。最后，上述聚合物的混合物的行为进行了研究，它被发现，在混合物中的聚合物的热解动力学保持不变，与纯聚合物的热解动力学相比。
The pyrolysis kinetics of low-density polyethylene, high-density polyethylene, polypropylene, and polystyrene has been studied at temperatures below 450 C. In addition, a literature review on the low-temperature pyrolysis of these polymers has been conducted and has revealed that the scatter in the reported kinetic data is significant, which is most probably due to the use of simple first-order kinetic models to interpret the experimental data. This model type is only applicable in a small conversion range, but was used by many authors over a much wider conversion range. In this investigation the pyrolysis kinetics of the forementioned polymers and a mixture of polymers has been studied at temperatures below 450 C by performing isothermal thermogravimetric analysis (TGA) experiments. The TGA experimental data was used to determine the kinetic parameters on the basis of a simple first-order model for high conversions (70-90%) and a model developed in the present study, termed the random chain dissociation (RCD) model, for the entire conversion range. The influence of important parameters, such as molecular weight, extent of branching and -scission on the pyrolysis kinetics was studied with the RCD model. This model was also used to calculate the primary product spectrum of the pyrolysis process. The effect of the extent of branching and the initial molecular weight on the pyrolysis process was also studied experimentally. The effect of the extent of branching was found to be quite significant, but the effect of the initial molecular weight was minor. These results were found to agree quite well with the predictions obtained from the RCD model. Finally, the behavior of mixtures of the aforementioned polymers was studied and it was found that the pyrolysis kinetics of the polymers in the mixture remains unaltered in comparison with the pyrolysis kinetics of the pure polymers.