The Research On Non-thermal Effects Mechanism And Regularity Of PET Hydrolysis Process Under Microwave Irradiation

It has been done a lot of work on PET depolymerization undermicrowave radiation and its dynamics research. Recent research indicatedthat the microwave non-thermal effect and energy relaxation phenomenonhas been found in research on the kinetics of PET depolymerizationmicrowave-assisted in water medium and the use of catalyst. The study onPET depolymerization in continuous-heating and intermittent heating undermicrowave irradiation, and investigation on the non-thermal effects ofmicrowave irradiation had effected on this process, it would provide thetheoretical to the harnessing of energy efficiency, and brought certainbreakthrough to the research field of microwave effects.It was studied that the process of PET hydrolysis in continuous-heatingand intermittent heating under microwave irradiation in different time whilethe temperature are at180℃,190℃and200℃in this paper. The liquid andsolid residues were analysed and characterized by gas chromatography (GC),infrared spectroscopy (IR), differential scanning calorimetry (DSC), and gelpermeation chromatography (GPC). It was investigated that the mechanismof the non-thermal effects of PET depolymerization in microwave combinedwith dynamic analysis. It was discussed that whether or not the intermittentheating catch up with the continuous-heating.The gas chromatography method was employed in analysis of liquidproducts of ethylene glycol(EG). It was found that the consistency riseswhen the temperature build-up and prolong the time, while the connectionwith the EG consistency and time appears definite regularity. Afterintegrating the analysis result of GC, IR,DSC and GPC, it was found that thefracture of long molecular chains of PET hydrolysis reaction undermicrowave intermittent heating has three process—the random, random -regular and the regular. The intermittent heating could catch up with thecontinuous-heating, and the mechanisms of PET depolymerization aresimilarity, namely the synergistic effect of the thermal effect and henon-thermal effect of microwave irradiation. In fact, the randomdepolymerization of PET was because of the microwave non-thermalreaction while the microwave thermal reaction results in the regulardepolymerization of PET, either synergy affect the whole reaction, themicrowave non-thermal reaction was obvious when the thermal effect wasweak, and the microwave non-thermal reaction was the strongest inintermittent heating under microwave irradiation.An dynamics analysis of the PET hydrolysis was made, the speedconstant and the activation energy of the chemical reaction was calculated.The result indicated that the activation energy of the continuous-heating wasmuch higher than the traditional while the intermittent heating was lowerthan other ways. But the reaction rates of two ways were much higher thanother ways, so it suggested that the former conclude was right.