Dielectric investigation of cold crystallization of poly(3-hydroxybutyrate)

✍ Scribed by Gamal R. Saad; Ashraf A. Mansour; Amany H. Hamed

• Book ID: 104164615
• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 758 KB
• Volume: 38
• Category: Article
• ISSN: 0032-3861
• DOI: 10.1016/s0032-3861(96)00979-2

✦ Synopsis

The dielectric behaviour of poly(3-hydroxybutyrate) (PHB) has been investigated for the glass (a) relaxation in the temperature and frequency ranges of -60 to 100°C and 103-lo5 Hz, respectively. Also, the crystallization kinetics of PHB has been studied dielectrically as a function of heating rate, time and temperature. Crystallinity has a marked influence on the glass relaxation characteristics owing to the relative constraint imposed on the amorphous phase by the crystallites. Furthermore, the results obtained showed that: (1) the optimum crystallization temperature is about 25°C; (2) the time at which crystallization starts is a function of the working temperatures and apparently is reduced to just a few minutes at 40°C; and (3) the crystallization process is completed within a period of less than 1 h in the temperature range 20-40°C. The bulk crystallization phenomena could be also described by the Avrami equation with an exponent N 3.8.