About the transformation of low T _m into high T _m poly(l-lactide)s by annealing under the influence of transesterification catalysts.

ABSTRACT: Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT _m) crystallites, having melting temperatures (T _m) < 180 °C into high melting (HT _m) crystallites having T _m values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HT _m crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes ther

SUBMITTER: Weidner SM 

PROVIDER: S-EPMC8693987 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature