PROCESS OF UNSATURATED POLYESTER RESIN SYNTHESIS ON A LABORATORY AND INDUSTRIAL-SCALE

A study of the progress of the synthesis of unsaturated polyesters, ba sed on anhydrides of phthalic and maleic acid and propylene glycol wit hout added catalysts was done. The reaction was carried out on a labor atory and industrial scale. The acid number and molecular weight distr ibution were determined. In the laboratory synthesis the amount of wat er produced during the reaction was also measured. Two steps in the re actions were observed. The first is the reaction of anhydrides with gl ycol producing monoester which is followed by step-growth polymerizati on reaction producing polymer. The kinetics of step-growth polymerizat ion reaction was found to be third order with an activation energy of E(a) = 54.3 kJ mol-1 and k(o) = 15.2 kg2mol-2s-1. The kinetic model wa s prepared and compared with results obtained from reactions carried o ut on an industrial scale. A method is presented for determining a hea ting program based on a limited reaction rate and a maximal reaction t emperature for a particular system. The MWD of polyester resin was det ermined and disagreement was found compared to the ''most probable'' M WD.