Shish Kebab Morphology induced in Polyhydroxybutyrate under Shear Flow

✍ Scribed by Lakshmi Sharma; Yoshino Ogino; Toshiji Kanaya

• Book ID: 102939001
• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 520 KB
• Volume: 289
• Category: Article
• ISSN: 1438-7492
• DOI: 10.1002/mame.200400181

✦ Synopsis

Abstract

Summary: In‐situ rheo small‐angle X‐ray scattering (SAXS), rheo‐light scattering, and rheo‐optical methods were employed to investigate the resultant morphology of polyhydroxybutyrate (PHB) under varying shear flow conditions. Immediately after shear flow application, a highly orientated structure emerged and row nucleation was identified at high shears. Only the initial stages of shish growth (we term the partial shish) were confirmed at excessively high shear conditions. However, only the kebabs were identified at medium shears, below this neither the shish nor kebab were observed. We believe this partial shish is a result of insufficient stability resulting from using such a low‐molecular‐weight species. We conclude that from our observations the shish kebab mechanism appears to display similarities to the Janeschitz‐Kriegl model of precursor formation.

Left: In‐situ rheo‐SAXS two‐dimensional pattern; kebab morphology observed at 100 s^−1^ for 1 s shear after 160 s. Right: In‐situ rheo‐optical micrograph; PHB row‐nucleated morphology observed at 100 s^−1^ for 1 s shear after 1 min.

imageLeft: In‐situ rheo‐SAXS two‐dimensional pattern; kebab morphology observed at 100 s^−1^ for 1 s shear after 160 s. Right: In‐situ rheo‐optical micrograph; PHB row‐nucleated morphology observed at 100 s^−1^ for 1 s shear after 1 min.