PRACTICAL ASPECTS OF POLYMERIZATION OF D,L-LACTIDE INITIATED WITH TETRAPHENYLTIN

Melt polymerization conditions for D,L-Lactide initiated with tetraphe nyltin were studied with regard to polymer molecular weight. The combi ned effect of time and temperature on polymer molecular weight and deg ree of conversion of D,L-Lactide is described. Polymerization at const ant initiator concentrations resulted in a narrow scattering of reprod ucible molecular weight values. The presence of air/moisture and other impurities during the melt polymerization most likely have a deterime ntal effect on molecular weight. After a short induction period the ra ther slow polymerization of D,L-Lactide resulted in a maximal molecula r weight followed by an almost constant value of molecular weight. (C) 1995 John Wiley & Sons, Inc.