The Thermal Degradation of Poly(-(D)-fl-Hydroxybutyric Acid): Part 2 Changes in Molecular Weight
The Thermal Degradation of Poly(-(D)-fl-Hydroxybutyric Acid): Part 2 Changes in Molecular Weight
- Polymer Degradation and Stability, 6(2), p.95-103, 1984 .
Changes in molecular weight occur in poly(-(o)-fl-hydroxybutyric acid)in the temperature range 170-200°C, at which latter temperature evolution of volatile products of degradation becomes significant. Two processes are involved in these changes in molecular weight. The more important is random chain scission at ester groups, which results in the formation of carboxyl and vinyl groups. Although this ultimately results in a drastic reduction in the molecular weight of the polymer, this is delayed in the early stages of the reaction by a condensation reaction between the terminal hydroxyl groups present in the original polymer and the terminal carboxyl groups, which were either originally present or formed in the chain scission process. This delay could have relevance to the industrial processing of this material.
Changes in molecular weight occur in poly(-(o)-fl-hydroxybutyric acid)in the temperature range 170-200°C, at which latter temperature evolution of volatile products of degradation becomes significant. Two processes are involved in these changes in molecular weight. The more important is random chain scission at ester groups, which results in the formation of carboxyl and vinyl groups. Although this ultimately results in a drastic reduction in the molecular weight of the polymer, this is delayed in the early stages of the reaction by a condensation reaction between the terminal hydroxyl groups present in the original polymer and the terminal carboxyl groups, which were either originally present or formed in the chain scission process. This delay could have relevance to the industrial processing of this material.