ALIPHATIC POLYESTERS AND THEIR COPOLYMERS SYNTHESIZED THROUGH DIRECT CONDENSATION POLYMERIZATION

Copolymers of lactic acid and the other hydroxyacid, such as glycolic acid and 6-hydroxyhexanoic acid, were prepared in an organic solvent t hrough the direct condensation. Glass-transition temperatures and melt ing points of these polymers are slightly different from those of poly mers obtained by the ring-opening polymerization process. The other ty pe polyesters from dicarboxylic acids and diols that have molecular we ights of up to 300 000 were also prepared by the same method. The high -molecular-weight polyester obtained can be processed into films and m olded products of a sufficient strength and toughness. Copolymers synt hesized from the reaction of polylactic acid and the other aliphatic p olyesters or cellulose derivative were also discussed. (C) 1998 Elsevi er Science Limited. All rights reserved.