Not only are microwaves notorious in food heating, but they exhibit interesting properties in different domains including chemical engineering. Their ability to concentrate heat transfer inside dielectric materials enhances process efficiency and permits high heating rates. Nonetheless, their effect on reactions is still controversial. While some researchers believe in non‐thermal effects due to the efficient conversion of microwave energy to enhance reactions without heat dissipation, others assert that microwave frequencies are not high enough to excite molecular bonds. In this study, paper cups pyrolysis is achieved in electrical and microwave TGA using two heating modes. The effect of microwaves on the kinetics of paper cups pyrolysis is shown to depend on the heating regime: at a moderate heating rate, microwave pyrolysis started at a lower temperature, while the pyrolysis in the electrical and microwave TGA have similar kinetic parameters at high heating conditions. This difference is linked with reaction mechanisms. At moderate heating conditions, cellulose decomposes first to an intermediate compound then to final products. The intermediate has a short reaction time and interacts with the microwave. Hence, hot spots at the molecular scale are generated in a short amount of time below the detectable limits of existing temperature measurements media. At a high heating rate, the decomposition of cellulose is direct and no effect is observed.

中文翻译：

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微波对纸杯热解动力学的影响

微波不仅在食物加热中臭名昭著，而且在化学工程等不同领域也表现出令人感兴趣的特性。它们将传热集中在介电材料内部的能力提高了工艺效率并允许高加热速率。但是，它们对反应的影响仍存在争议。尽管一些研究人员认为由于微波能量的有效转化以增强反应而不散发热量而产生了非热效应，但另一些研究人员则认为微波频率不足以激发分子键。在这项研究中，纸杯热解是在电和微波TGA中使用两种加热模式实现的。结果表明，微波对纸杯热解动力学的影响取决于加热方式：在中等加热速率下，微波热解从较低的温度开始，而电热和微波TGA中的热解在高加热条件下具有相似的动力学参数。这种差异与反应机制有关。在中等加热条件下，纤维素首先分解为中间体化合物，然后分解为最终产物。该中间体反应时间短，并且与微波相互作用。因此，在不到现有温度测量介质的可检测极限的短时间内，就会在分子尺度上产生热点。在高加热速率下，纤维素的分解是直接的，没有观察到效果。在中等加热条件下，纤维素首先分解为中间体化合物，然后分解为最终产品。该中间体反应时间短，并且与微波相互作用。因此，在现有温度测量介质的可检测极限以下的短时间内，会在分子级产生热点。在高加热速率下，纤维素的分解是直接的，没有观察到效果。在中等加热条件下，纤维素首先分解为中间体化合物，然后分解为最终产品。该中间体反应时间短，并且与微波相互作用。因此，在现有温度测量介质的可检测极限以下的短时间内，会在分子级产生热点。在高加热速率下，纤维素的分解是直接的，没有观察到效果。