【作者】 金佳梅；

【导师】 张东；

【作者基本信息】 温州大学 ， 应用化学， 2011， 硕士

【摘要】 近年来,聚酯解聚技术在我国蓬勃发展,聚酯解聚的方法也多种多样,但对聚酯解聚机理的研究却远落后于其技术的发展。然而日渐受重视的由聚酯的广泛应用引起的环境问题要求我们不得不对其机理作深入研究。对微波环境下的PET水解聚过程进行研究,不但可以为微波解聚工业化提供理论支持,还可以为微波非热效应提供有效支持。本文主要研究聚酯(PET)在微波环境中,水与PET质量比为10:1时,温度分别在190℃、180℃、170℃下,不同时间的纯水解聚过程。通过对解聚液相产物及固体残留物的测定、分析和表征来研究反应,探讨微波下PET解聚的反应机理,同时建立相应的动力学模型。利用气相色谱(GC)、红外光谱(IR)、凝胶色谱法(GPC)、热分析联用(TG-DSC)、扫描电镜(SEM)等分析测试手段,对PET解聚程度、解聚残留物的表观形貌和热力学行为进行了研究,同时对微波在反应过程中提供的能量进行了计算。通过采用气相色谱法对液相产物中乙二醇(EG)浓度的测定,发现同一温度下,随着时间的递进,液相产物中EG浓度不断增加;相应的同一反应时间,温度越高,测得的EG浓度也越高,但是EG浓度随时间的变化关系并不是简单的一次函数,表现出跳跃性。综合气相、红外、热重、扫描电镜等测试手段的分析结果,推断PET在微波环境下的解聚反应,其长链的断裂有无规和有规两个过程,反应初期主要进行的是无规断裂,有规断裂还不明显,后期则主要是有规断裂。通过对微波在反应中提供的能量进行分析,发现微波能量的多少与PET解聚程度呈一定的相关性,并初步建立了微波能量作用模型。对以往PET解聚的动力学模型进行优化,建立相应的反应速率方程,计算出化学反应的速率常数和活化能。结果表明,微波环境下的PET解聚反应的活化能比其他方式下PET解聚反应的活化能要低很多,结合前面分析得到的微波下PET无规解聚过程,说明正是微波的非热效应使PET发生无规解聚,反应在较短时间内就产生大量解聚产物,改变了反应路径,使反应更容易进行。更多还原

【Abstract】 In recent years, PET depolymerization technology boomed in China, the methods of PET depolymerization are diverse, but the mechanism of it is far behind the technology. However, increasing attention to the environmental problems caused by the extensive use of PET requires us to have in-depth study of its mechanism. The study on PET depolymerization in microwave, it will not only provide the theoretical to the industrialization of PET depolymerization in microwave, but also give effective support to the non-thermal effects of microwave irradiation.This paper studied the process of PET depolymerization in pure water with microwave in different time while the water and PET mass ratio is 10:1 and the temperature are at 190℃, 180℃and 170℃. We studied the action by measure, analyse and characterize the liquid and solid residues, investigated the mechanism of PET depolymerization in microwave and established the corresponding dynamic model. By using gas chromatography (GC), infrared spectroscopy (IR), gel permeation chromatography (GPC), thermal analysis spectrometer (TG-DSC), scanning electron microscopy (SEM) and other methods, we analysed the degree of PET depolymerization and the morphology and thermotics of residues, while the energy supplied by microwave to the reaction was calculated at the same time.We used gas chromatography method to measue the consistency of ethylene glycol(EG) in the liquid residues and found that the consistency rises by the time under a certain temperature and also rises when raise the tempetature at the certain time, while the relationship between the EG consistency and time is not a simple linear function but an uneven one. After integrating the analysis result of gas chromatography (GC), infrared spectroscopy (IR), gel permeation chromatography (GPC), thermal analysis spectrometer (TG-DSC), scanning electron microscopy (SEM) and other methods, we concluded that the fracture of long molecular chains in PET depolymerization in micrwave has two process, while one is random and the other is regular. At the early stage of the reaction random fracture is the main one when the regular fracture is not clear, but in the later stage regular fracture is the main one. By analyzing the energy provided by microwave in the reaction, we found that the amount of microwave energy and the degree of PET depolymerization are some related, and we established the function model of microwave energy.We have optimizated the former kenetics model of the PET depolymerization, established the corresponding reaction rate equation and calculated the speed constant and the activation energy of the chemical reaction. The result indicated that under the microwave environment the activation energy of the PET depolymerization was lower than other ways, front the union the analysis obtains under the microwave the PET random depolymerization process, showing is precisely the microwave non-thermal reaction causes PET to have the random depolymerization, responded that in a short time produces the massive depolymerization product, change the way of reaction, easier the reaction. .更多还原