کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5204876 | 1381974 | 2006 | 9 صفحه PDF | دانلود رایگان |

Thermal degradation behaviours of poly(3-hydroxybutyric acid) (P(3HB); bacterial poly[(R)-3-hydroxybutyric acid] and synthetic poly[(R,S)-3-hydroxybutyric acid] samples, were examined under both isothermal and non-isothermal conditions. The inverse of number-average degree of polymerisation for all P(3HB) samples decreased linearly with degradation time during the initial stage of isothermal degradation at a temperature ranging from 170-190 °C. In addition, crotonyl unit was detected in the residual polymer samples as main Ï-chain-end. These results indicate that the dominant thermal degradation reaction for P(3HB) is a random chain scission via cis-elimination reaction of P(3HB) molecules. It was found that the presence of either Ca or Mg ions enhances the depolymerisation of P(3HB) molecules, while that Zn ions hardly catalyse the reaction. As a result, a shift of thermogravimetric curves toward the lower temperature regions was observed for the P(3HB) samples containing high amounts of Ca and Mg compounds.
Journal: Polymer Degradation and Stability - Volume 91, Issue 4, April 2006, Pages 769-777