Thesis (Ph.D.)--Chulalongkorn University, 2004

Converses the used Polyethylene terephthalate classified as a great deal of waste available in Thailand to its original reactant(DimethyI terephthalate). Regarding the procedure, the depolymerization process was performed in a cylindrical reactor capacity 70 ml. which was constructed with stainless steel 316. PET was dissolved in methanol solution and mixed with these catalyst. The reaction was operated in temperature range 160 ํC-190 ํC, reaction time in the range of 5 min-40 min. an ratio of catalyst-to-PET 0.3%-2.0% by weight. The experimental result indicated that the optimal condition of the depolymerization of PET with dibutyltin oxide as a catalyst was at the temperature ranging from 170 ํC to 180 ํC, the reaction time of 20 min to 25 min and the catalyst-to-PET ratio of 0.8%. The yield percentage of the product(DMT) was 97. In addition, this research had also studied the model of kinetic depolymerization of PET using dibutyltin oxide as acatalyst. The result showed that it was a first-order reaction with ht activation energy of 154.05 KJ/mol