COPOLYMERS OF L-LACTIDE AND D,L-LACTIDE WITH 6-CAPROLACTONE - SYNTHESIS AND CHARACTERIZATION

L- and D,L-lactide copolymers with 6-caprolactone were synthesized and characterized in a wide range of compositions. The polymerizations we re carried out in batch at 130-degrees-C, with Sn(II) octoate as a cat alyst, a monomers/initiator mole ratio of 5000/1 and a reaction time o f 48 h. The copolymers having from 5 to 40 wt.-% of 6-caprolactone are characterized by higher values of non-reacted monomers and deviations of the polymer composition from the feed ratio. In the same interval of compositions, L-lactide copolymers showed progressive hardening wit h time at room temperature, attributable to the tendency to crystalliz ation of homopolymeric sequences. This behaviour was more deeply studi ed in the case of poly(L-lactide-co-6-caprolactone) with 30 wt.-% of 6 -caprolactone. H-1 NMR at 300 MHz appeared to be a suitable method for the determination of the monomer sequence.