Biodegradable fibers of poly(3‐hydroxybutyrate) produced by high‐speed melt spinning and spin drawing

The effects of high-speed melt spinning and spin drawing on the structure and resulting properties of bacterial generated poly(3-hydroxybutyrate) (PHB) fibers were investigated. The fibers were characterized by their degree of crystallinity by differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS), their orientation by WAXS, and the textile physical properties. The WAXS studies revealed that the fibers spun at high speeds and high draw ratios possessed orthorhombic (α modification) and hexagonal (β modification) crystals, the latter as a result of stress-induced crystallization. The fiber structures formed during these processes were fibril-like as the atomic force microscopy images demonstrated. The maximum physical break stress, the modulus, and the elongation at break observed in the fibril-like spin drawn fibers were about 330 MPa, 7.7 GPa, and 37%, respectively. The fibers obtained by a low draw ratio of 4.0 had spherulitic structures and poor textile physical properties. The PHB pellets were analyzed by their degradation during the processes of drying and spinning and by their thermal and rheological properties. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2841–2850, 2000