Kinetics of co-polyesters of hydroquinone diacetate and its methyl derivative with terephthalic acid

Abstract

The synthesis of hydroquinone diacetate (HQDA), methyl hydroquinone diacetate (MHQDA) and terephthalic acid (TA)-based co-polyesters by melt-step growth polymerization is reported. Two different sets of melt polymerization reactions were carried out, consisting of set A, HQDA+MHQDA (25:25 mol%)+TA (50 mol%), and set B, HQDA+MHQDA (20:30 mol%)+TA (50 mol%). Kinetic models for co-polyesterification reaction were critically examined and a new simple model has been proposed and tested. The performance of sodium acetate and zinc acetate as catalysts were investigated for the polyesterification reaction. Four different reaction temperatures (255, 260, 265 and 270°C) were employed for the kinetic study of both sets A and B. Acetic acid generated by the reaction of HQDA, MHQDA and TA was measured as a function of time. This experimental data were analyzed and various chemical kinetic models in the literature were compared with the suggested model to explain the most realistic reaction mechanism of polyesteri&filigcation reactions. Sodium acetate was found to be better catalyst than zinc acetate for the tri-component system. An induction period was found to be present for the catalyzed and non-catalyzed runs.

Keywords:

• MELT POLYMERIZATION
• CO-POLYESTERIFICATION
• LIQUID CRYSTALS
• REACTION KINETICS