Mechanism and kinetics of the hydrolytic degradation of amorphous poly(3-hydroxybutyrate)

Péter Polyák, Dóra Szemerszki, G. Vörös, B. Pukánszky

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5 Citations (Scopus)

Abstract

Amorphous poly(3-hydroxybutyrate) films prepared by compression molding and solvent casting were degraded in aqueous media at different pH values. The time dependence of degradation was monitored by the measurement of weight loss, the extraction of the degradation products from the degrading sample, as well as by UV-Vis spectrophotometry and HPLC analysis of the aqueous solution. The results proved that degradation takes place mainly in the bulk of the samples and not on their surface. The overall rate of degradation depends strongly on pH; it increases with increasing pH values. Metabolite extraction and chromatography proved that degradation does not occur randomly, but with larger frequency at the end of the chains. By assuming that the hydrolysis of PHB is a SN2 type nucleofil substitution reaction, a kinetic model was proposed which describes the formation of various degradation products. The diffusion of metabolites was also accommodated into the model thus the concentration in the aqueous solution could also be predicted well. The correlation between prediction and experimental results is excellent. The model can be extended also for the description of the hydrolytic degradation of other aliphatic polyesters.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalPolymer Degradation and Stability
Volume140
DOIs
Publication statusPublished - Jun 1 2017

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Keywords

  • Degradation
  • Hydrolysis
  • Kinetics
  • Polyhydroxyalkanoate
  • Polyhydroxybutyrate

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Polymers and Plastics
  • Materials Chemistry

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