【作者】 王禹；

【导师】 王宝辉； 张东；

【作者基本信息】 大庆石油学院 ， 化学工艺， 2006， 硕士

【摘要】 近年来随着世界上 PET 聚酯消费量的迅猛增加,由此而产生的纤维及废旧塑料也不断增多。大力开发聚酯回收技术,处理废弃聚酯已成为聚酯工业可持续发展的关键之一。目前 PET 聚酯回收主要有水解、醇解、胺解等方法,而真正实现材料循环利用、可持续发展的唯一途径就是 PET 水解法。本实验以微波作为热源对 PET 水解反应进行了研究,考察了解聚反应条件对 PET解聚率的影响;对解聚反应动力学进行了初步研究;通过用显微镜和扫描电镜对未完全解聚的 PET 外部形貌和脆断面形貌进行研究,揭示了反应过程和反应机理,结论如下:1.(1)压力、时间、解聚水量和微波输出功率对 PET 的解聚反应影响依次为:时间﹥压力﹥解聚水量﹥微波输出功率。其中时间和压力为主要影响因素,解聚水量和微波输出功率为次要影响因素。最佳反应条件为:时间 105 min、压力 19 bar、水与 PET质量比 6、微波输出功率 500 W。(2)草酸钾、醋酸钾和醋酸锌对 PET 微波的解聚反应均有催化作用,其中草酸钾用量在 1%时效果最好,可使 PET 解聚率达到 88.5%;醋酸钾催化剂用量在 0.5%时效果最好,也可使 PET 解聚率达到 85%以上;醋酸锌用量变化对 PET 解聚率影响不大,可使 PET 解聚率达到 60%以上。综合考虑催化剂成本和催化效果,三种催化剂用量在 0.5～2%较为合适,催化效果依次为:草酸钾>醋酸钾>醋酸锌。(3)PET 粒度增大,解聚率减小。(4)PET 结晶度增大,解聚率下降,但下降幅度不大,说明原料 PET 的结晶度对解聚率的影响很小,解聚反应在 PET 结晶部分和非结晶部分难易程度相近,反应并非首先在非晶区进行。2. PET 解聚率在 5.06%～35.81%时,作图法求得反应级数近似为一级反应。微波辐射下的 PET 水解反应过程为无规解聚与有规解聚相结合的过程。3. 反应初期,PET 聚酯切片形状未变,但变得很脆,这说明聚酯颗粒内部发生了变化;显微镜观察反应后期扩散到水中固体的形状为一团一团的大块物质,说明反应不仅仅由原料颗粒外表面向内部进行,而是内部和外表面同时进行反应;对未完全解聚的PET 切片截面的扫描电镜分析说明,截面上有部分单体 TPA 溶于碱液中,说明反应是在聚酯颗粒内部和外表面同时进行的。更多还原

【Abstract】 Recently with the rapid incresing of the PET polyester consumption in the world, fibreand waste plastic were continuously increasing. It is the key technology for polyesterindustry continuance development that developping on polyester recovery technology anddisposalling of polyester abandoned.. At present, the methods used to recovery PET polyesterare hydrolyzation, alcoholysis and amination, etc. However, only hydrolyzation of PET canrealize recycling utilization of resource and keep developing forever.We have researched on the hydrolyzation of PET using microwave as heat source. Theeffects of reaction condition on the depolymerization rate of PET were studied. At the sametime, the kinetics of depolymerization reaction was investigated. The surface and sectionmorphology of undepolymerized PET residues were pictured with Polarized Microscopy(POM) and Scanning Electronic Microscopy (SEM). The results indicate the process andmechanism of the depolymerization reaction. The following results were obtained:1. (1) The effective degree of factors on the depolymerization reaction is ordered inreaction time, pressure, water and microwave power. Reaction time and pressure were themajor factors. The best reaction conditions are that: reaction time is 150 min, pressure is 19bar, mass rate of water and PET is 6, microwave power is 500 W. (2) Dipotassium oxalate,Potassium acetate and Zinc acetate all have catalysis on the depolymerization reaction of PET.The order is oxalate> acetate> zinc acetate. Dipotassium oxalate has the best effect on thedepolymerization reaction and the depolymerization rate can reach 88.5% when the loading ofcatalyst is 1%. The depolymerization rate can exceed 85% when the loading of Potassiumacetate is 0.5%. The quantity of Zinc acetate makes no difference to .depolymerization rate,and the depolymerization rate can reach 60%. The optimal quantity of catalyst is 0.5~2%. (3)With the increasing of particle size of PET, the rate of depolymerization decreased. (4) Therate of PET depolymerization decreased slightly with the increasing of crystallinity of PET,This indicated that the crystallinity of PET has a little effect on the reaction, and thehydrolysis was not preferentially occurred on the amorphous phase of PET resin.2. The reaction order is close to unity by drawing when the depolymerization rate isbetween 5.06% and 35.81%, which is different from that by calculation. Hydrolyzationreaction of PET under microwave radiation is a combined process of rulelessdepolymerization and ruly depolymerization.3. At the beginning of the reaction, the shape of PET resin was not changed but the resinbecame fragile. This proved that some changes happened inside the PET resin. It can be alsoobserved that big blocks of PET were diffused into water, which showed that the hydrolysisreacted not only outside the PET resin, but also inside the PET resin.更多还原