Transition of spherulite morphology in a crystalline/crystalline binary blend of biodegradable microbial polyesters

Taizo Kabe, Tomoko Sato, Ken Ichi Kasuya, Takaaki Hikima, Masaki Takata, Tadahisa Iwata

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Crystalline/crystalline binary blend films of microbial polyesters composed of poly[(R)-3-hydroxybutyrate-co-(R)-3hydroxyhexanoate] (P(3HB-co-3HH)) and poly[(R)-3-hydroxybutyrate] (P(3HB)) that exhibit a morphological change are prepared by solvent casting. Differential scanning calorimetry measurements indicate that P(3HB-co-3HH) and P(3HB) are miscible for all blend ratios because a single glass transition temperature is observed. Polarization optical microscopy is used to investigate the transition of spherulite morphology and measure the radial growth rate of spherulites in the blend films. P(3HB-co-3HH) and P(3HB) contain positive spherulites, whereas in the binary blends, spherulite morphology changes from positive to negative. This change is related to the different growth rates of P(3HB-co-3HH) and P(3HB) lamellar crystals. Partial enzymatic degradation of the film surfaces reveals that the lamellar crystals of negative spherulites are oriented both perpendicular and parallel to the radial direction of spherulites. A new growth mechanism for spherulites in crystalline/crystalline blends is constructed from the results obtained for the blend films.

Original languageEnglish
Pages (from-to)271-277
Number of pages7
Issue number1
Publication statusPublished - 2014 Jan 14
Externally publishedYes


  • Binary blend
  • Polyhydroxyalkanoate
  • Transition of spherulite morphology

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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