Time-Resolved X-ray Diffraction Study on Poly[(R)-3-hydroxybutyrate] Films during Two-Step-Drawing: Generation Mechanism of Planar Zigzag Structure

• DOI: 10.1021/bm050152s
• Publication Date: 2005-05-09T04:21:23Z
• Authors: Tadahisa Iwata; Masahiro Fujita; Yoshihiro Aoyagi; Yoshiharu Doi; Tetsuro Fujisawa
• Keywords: Small-angle X-ray scattering; Zigzag; Coalescence (physics); Crystal (programming language); Monoclinic crystal system

Uniaxially oriented films with high tensile strength were processed from ultrahigh-molecular-weight poly[(R)-3-hydroxybutyrate] (P(3HB)) by a method combining hot-drawing near the melting point of polymer and two-step-drawing at room temperature. In two-step-drawn subsequently annealed film, P(3HB) molecular chains fall into two states: 2/1 helix (α-form) planar zigzag (β-form) conformations. The mechanism for generating β-form during was investigated time-resolved synchrotron wide- small-angle X-ray scattering measurements (WAXD SAXS), together measurement stress−strain curves. It found that improvement mechanical properties is due to not only orientation but also generation drawing. crystal structures α-form remained unchanged until yield curve. At point, long period obtained SAXS doubled new reflection indicative observed on equatorial line in WAXD. intensity increased an increase ratio pattern changed two-point along meridian cross streaking line, demonstrating close alignment shish-kebab structures. intensity, size decreased two-step-drawing. Based these results, mainly introduced free amorphous regions between lamellar crystals, structural transformation occurs deformed crystals.