Mechanical properties and highly-ordered structural analysis of elastic poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] fibers fabricated by partially melting crystals

Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)) elastic fibers were prepared at temperatures close to or below the melting temperature by partially melting thin crystals with no associated reduction in molecular weight. The obtained fibers exhibited elastic properties and good long-term stability of their mechanical properties, even after aging for 330 days. Cycle tests were conducted with simultaneous in-situ wide-angle X-ray diffraction and small-angle X-ray scattering using synchrotron radiation to investigate the mechanisms governing these fibers’ elasticity. It was determined that the main factor contributing to the elasticity is the reversibility between the random coil structure of tie molecules and the planar zigzag conformation of molecular chains in response to loading and unloading.