本文以二甘醇(DEG)为醇解剂、无水氯化亚锡(SnCl2)为催化剂，采用一步进料和分步进料醇解法，研究了PET瓶片、PET粒料和PET纤维的醇解反应。通过SEM、DSC、TG、FTIR、1H NMR等分析手段表征了不同形态PET材料及其醇解产物的结构与热性能。结果表明： PET材料化学结构不会因为它的形态发生变化，但熔点和结晶度有明显的不同，其中PET纤维的熔点(253 ℃)和结晶度(43.44%)均高于PET瓶片、PET粒料的。当醇解温度220 ℃、反应为180 min时，一步进料醇解法的PET材料的醇解率依次为：瓶片≈粒料?纤维(依次为98.8%、98.8%、80.8%)；当醇解温度为220 ℃、反应时间为90 min时，分步进料醇解法的PET瓶片和粒料的醇解率均达到100%、纤维的醇解率达到92.5%；一步进料醇解法的醇解率依次为瓶片42.1%、粒料38.5%、纤维28.0%，分别提高了57.9%、61.5%、64.5%。说明本文研发的分步进料醇解法技术可以使PET材料醇解反应时间缩短一半，且PET纤维的醇解率有明显的提升。
The glycolysis reactions of PET bottle, PET particle and PET fibers were investigated using diethylene glycol (DEG) and SnCl2 as the catalyst in a one-step feed and stepwise feeding process. The structural and thermal properties of the PET materials and their glycolysis products were characterised by SEM, DSC, TG, FTIR, 1HNMR and other analytical means. The results showed that the chemical structures of the three different forms of PET materials were similar with no significant changes. The melting point (253 °C) and crystallinity (43.44%) of the PET fibers were higher than those of the PET bottle and PET particle. When the glycolysis temperature was 220 ℃ and the reaction time was 180 min, the conversion ratio of PET materials by one-step feeding process was: bottle ≈ particle ? fibres (98.8%, 98.8%, 80.8% in order); When the glycolysis temperature was 220 ℃ and the reaction time was 90 min, the conversion ratio of PET bottle and particle by stepwise feeding process reached 100%, and the conversion ratio of fibers reached 92.5%. The conversion ratio of one-step feeding process was 42.1% for bottle, 38.5% for particle and 28.0% for fibers, which increased by 57.9%, 61.5% and 64.5% respectively. The result shows that the stepwise feeding process in this paper can reduce the glycolysis time of PET material by half, and the conversion ratio of PET fibers can be improved significantly.