Thermal and surface properties of fibers
made from fiber-forming gelatin-g-polyacrylonitrile grafted copolymers
Polimery 2000, No 3, 172
SummaryDifferential 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). T'he 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, γσD, and the energy of specific interactions, -ΔGsp) 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.