Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l-lactide-co-glycolide)

We investigated the effect of isothermal annealing on the degree of crystallinity and mechanical properties of a random copolymer‐poly(l‐lactide‐co ‐glycolide) (PLLGA)‐with monomer molar ratios of 85/15 (PLLGA85/15) by performing polarizing optical microscopy, differential scanning calorimetry, and X‐ray diffraction, and studying the tensile properties. Isothermal annealing of PLLGA at 130 °C was conducted to improve the degree of crystallinity of the copolymer; the maximum degree of crystallinity (44.5%) was achieved after 60 min of annealing. The crystal size/perfection was observed to increase with annealing time. The highest tensile strength of 65.8 MPa was achieved after 80 min of annealing. However, the degree of crystallinity and tensile strength can only reach to certain extent. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)