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

A study of the progress of the synthesis of unsaturated polyesters, based on anhydrides of phthalic and maleic acid and propylene glycol without added catalysts was done. The reaction was carried out on a laboratory and industrial scale. The acid number and molecular weight distribution were determined. In the laboratory synthesis the amount of water produced during the reaction was also measured. Two steps in the reactions were observed. The first is the reaction of anhydrides with glycol producing monoester which is followed by step-growth polymerization reaction producing polymer. The kinetics of step-growth polymerization 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 was prepared and compared with results obtained from reactions carried out on an industrial scale. A method is presented for determining a heating program based on a limited reaction rate and a maximal reaction temperature for a particular system. The MWD of polyester resin was determined and disagreement was found compared to the ''most probable'' MWD.