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Glass transition and the rigid amorphous phase in semicrystalline blends of bacterial polyhydroxybutyrate PHB with low molecular mass atactic R, S-PHB-diol |
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| Authors: | S.H. El-Taweel A.A. Mansour H. Seliger |
| Affiliation: | a Sektion ‘chemische Funktionen in Biosystemen’, University of Ulm, D-89069 Ulm, Germany b Institut für angewandte Analysentechnik, Multscherstr. 2, D-89077 Ulm, Germany c Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt d Abteilung Angewandte Physik, University of Ulm, 89069 Ulm, Germany |
| Abstract: | The glass transition and the crystallinity of blends of isotactic bacterial PHB and low molecular mass atactic R, S-PHB-diols was investigated by means of differential scanning calorimetry (DSC), temperature-modulated DSC and dielectric spectroscopy. It was found that (i) Tg of crystallized blends is much lower than Tg of quenched blends, (ii) the semi-crystalline blends can only be described with a three-phase model. From the experimental results the amount of the oligomer component in the mobile amorphous as well as in the rigid amorphous phase was determined. It could be shown that the low molecular mass atactic R, S-PHB-diol is enriched in the mobile amorphous phase of the semi-crystalline blends, but 5-15% oligomer remains, however, in the rigid amorphous phase. |
| Keywords: | Polyhydroxybutyrate Blends Low molecular mass atactic R, S-PHB-diols |
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