Study of the Effect of External Factors on the Structural and Dynamic Parameters of Film Materials Based on Poly(3-Hydroxybutyrate) and Polyactide

Abstract

The structure of film and fibrous materials based on poly(3-hydroxybutyrate)–polylactide blends has been studied. Ultrafine fibers have been spun by the electrospinning of a polymer solution; the films have been prepared by casting onto a glass substrate. Using optical microscopy, it has been shown that, depending on the fiber composition, the fibers have different diameters and geometries. The features of the crystalline and amorphous structures of the composites have been studied by the spin-probe electron paramagnetic resonance method and differential scanning calorimetry. The addition of 10 and 30% of polylactide to the composite leads to a slowdown of the molecular mobility in the film and fibrous materials and an increase in the enthalpy of melting of the ultrafine fibers. At a polylactide content in the blend of 30%, a kink in the dependences of the enthalpy of melting, correlation time, and radical concentration is observed. Annealing at a temperature of 140°C and exposure to an aqueous medium at 25 and 70°C for 3 h have a significant effect on the polymer structure: the enthalpy of melting and molecular dynamics increase, while the radical concentration in the ultrafine fibers and the film material decreases. Ozonolysis has a complex effect on the structure of the ultrafine fibers.