Analysis of the Structure of Ultrafine Fibers Based on Poly(3-hydroxybutyrate) and Polylactide: Effect of External Factors

Ultrafine fibers of a blend composite of a biodegradable natural polyester poly(3-hydroxybutyrate) and polylactide are obtained by electrospinning. Using optical microscopy, it is shown that the fibers, depending on composition, have different diameters and geometries. The features of the crystalline and amorphous structure of the composite are investigated by the EPR probe technique and DSC. Adding 10, 30, 50, and 70% poly(3-hydroxybutyrate) to the composite dramatically reduces the molecular mobility of the probe. Annealing at 140°C and exposure in an aqueous medium at 70°C have a strong effect (significantly shorten the correlation time of probe rotation) in polylactide fibers. In blend composites and poly(3-hydroxybutyrate), these changes are not so significant.