Thermal and surface properties of fibers made from fiber-forming gelatin-g-polyacrylonitrile grafted polymers

Differential thermal analysis and inverse gas chromatography were used to study thermal and surface properties of fibers made from gelatin-g-polyacrylonitrile (PAN) grafted copolymers and to compare them with those of the fibers produced from pure PAN and with those of gelatin (Figs. 1, 2; Tables 1-3). The thermal and surface properties of the grafted copolymer prepared at the AN/gelatin weight ratio equal to 2 (degree of grafting 150%), are close to those of unmodified PAN. The temperature ranges of oxidation and cyclization of PAN grafted side chains (490-570 K) and of the fundamental destructive changes of the copolymer (740-920 K) were found to be identical with those of pure PAN. The surface properties (dispersive component of the surface energy, gamma(sigma)(D), and the energy of specific interactions, -Delta G(sp)) indicate that, at the degree of grafting equal to 150%, strong interactions of acrylonitrile's C-N groups with gelatin's polar centers make primarily PAN moieties occur on the surface of the fibers made from the copolymer; the grafted PAN chains shielding gelatin's active centers. Wide-angle X-ray scattering (WAXS) studies (Figs. 3-7) showed the copolymer fibers to contain ca. 34% of paracrystalline regions vs. the 53% in the fibres made from pure PAN.