WEIGHT LOSSES AND MOLECULAR-WEIGHT CHANGES CORRELATED WITH THE EVOLUTION OF HYDROXY-ACIDS IN SIMULATED IN-VIVO DEGRADATION OF HOMOPOLYMERS AND COPOLYMERS OF PLA AND PGA
M. Hakkarainen et al., WEIGHT LOSSES AND MOLECULAR-WEIGHT CHANGES CORRELATED WITH THE EVOLUTION OF HYDROXY-ACIDS IN SIMULATED IN-VIVO DEGRADATION OF HOMOPOLYMERS AND COPOLYMERS OF PLA AND PGA, Polymer degradation and stability, 52(3), 1996, pp. 283-291
Homo- and copolymers of poly(lactide)s (PLA) and poly(glycolide)s (PGA
) were hydrolysed at 37 and 60 degrees C for periods up to 80 days. We
propose that the hydrolyses of PLA100 (100% L-lactide), PLA37.5GA25 (
75% D,L-lactide and 25% glycolide) and PLA25GA50 (50% D,L-lactide and
50% glycolide) in buffer solutions at 37 and 60 degrees C proceed in t
hree stages. During the first stage the molecular weights decrease rap
idly with little weight loss. In stage two, the decrease in molecular
weight slows down and severe weight loss starts in parallel with which
monomer formation is initiated. During the final third stage, when to
tal weight loss is observed, about 50% of the polymer is converted to
monomer. The hydrolyses of the soluble oligomers continues until all a
re transferred to lactic acid and glycolic acid. (C) 1996 Elsevier Sci
ence Limited