FASTER PLASTICIZERS PRODUCTION BY MICROWAVE IRRADIATION

Abstract

Plasticizers are esters used to confer plasticity to polymer goods. They are prepared by esterification between a carboxylic acid or anhydride and a heavy alcohol. Esterification is a very slow reaction and its batches may last more than 12 hours of processing [1]. An empirical study of maleic anhydride (MA) esterification with 2-ethyl hexanol (EHO) esterification was done to explore the non-thermal effect of microwaves [2]. In this work a complete 2^3 factorial design and a statistical regression were conducted aiming to stablish empirical complete chemical kinetic equations under microwave heating and under conventional electric heating. The result was a series of six kinetic equations, as shown in Table 1; all parameters are related to -r_MA=k_0∙exp⁡(-E/RT)∙C_MA^nMA∙C_EHO^nEHO, T in Kelvin, and R = 1.9872 cal/mol.K. For a deeper understanding of the results a computer simulation procedure was developed to stimulate this reaction in an isothermal ideal reactor with constant process volume. Interesting numerical results lead to the conclusions that microwave enhanced this slow esterification to a fast reaction as is shown in Figure 1 in the curve labelled ‘microwave heating with 0.012 M of PTSA’.