Thermal Degradation of Poly(3-hydroxyalkanoates):  Preparation of Well-Defined Oligomers

The thermal degradation of the biodegradable bacterial polyesters poly(3-hydroxybutyrate), PHB, poly(3-hydroxyvalerate), PHV, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), 0−21 mol % of hydroxyvalerate, was studied. At moderately low temperatures (170−200 °C), the main product is a well-defined...

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Bibliographic Details
Published in:Biomacromolecules 2002-01, Vol.3 (1), p.219-224
Main Authors: Nguyen, Sophie, Yu, Ga-er, Marchessault, R. H
Format: Article
Language:English
Subjects:
Chromatography, Gel
Hot Temperature - adverse effects
Hydroxybutyrates - metabolism
Magnetic Resonance Spectroscopy
Polyesters - metabolism
Spectrometry, Mass, Fast Atom Bombardment
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Summary:The thermal degradation of the biodegradable bacterial polyesters poly(3-hydroxybutyrate), PHB, poly(3-hydroxyvalerate), PHV, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), 0−21 mol % of hydroxyvalerate, was studied. At moderately low temperatures (170−200 °C), the main product is a well-defined oligomer, especially a 500−10 000 g/mol macromolecule, which contains one unsaturated end group, predominantly a trans-alkenyl end group, as well as a carboxylic end group. The process was studied regarding the effect of the copolymer composition and reaction time at 190 °C. During the first few hours of reaction, the thermal degradation of PHB and PHV followed a kinetic model of random scission, but eventually auto-acceleration of the pyrolysis was detected, probably due to the influence of the crotonate end groups of the oligomers formed. Ten-time scale-up experiments on a Brabender instrument were successfully undertaken.
ISSN:1525-7797
1526-4602
DOI:10.1021/bm0156274