Environmental degradation of lignin/poly(hydroxybutyrate) blends
Blends of lignin and poly(hydroxybutyrate) (PHB) were obtained by melt extrusion. They were buried in a garden soil for up to 12 months, and the extent and mechanism of degradation were investigated by gravimetric analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR) over the entire range of compositions. The PHB films were disintegrated and lost 45 wt% of mass within 12 months. This value dropped to 12 wt% of mass when only 10 wt% of lignin was present, suggesting that lignin both inhibited and slowed down the rate of PHB degradation. TGA and DSC indicated structural changes, within the lignin/PHB matrix, with burial time, while FTIR results confirmed the fragmentation of the PHB polymer. XPS revealed an accumulation of biofilms on the surface of buried samples, providing evidence of a biodegradation mechanism. Significant surface roughness was observed with PHB films due to microbial attack caused by both loosely and strongly associated micro-organisms. The presence of lignin in the blends may have inhibited the colonisation of the micro-organisms and caused the blends to be more resistant to microbial attack. Analysis suggested that lignin formed strong hydrogen bonds with PHB in the buried samples and it is likely that the rate of breakdown of PHB is reduced, preventing rapid degradation of the blends.
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|Item Type:||Journal Article|
|Keywords:||Biopolymer; degradation; lignin; poly(hydroxybutyrate) (PHB); soil; thermal properties|
|Subjects:||Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Chemical Characterisation of Materials (030301)|
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Physical Chemistry of Materials (030304)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Synthesis of Materials (030306)
|Divisions:||Current > Schools > School of Chemistry, Physics & Mechanical Engineering|
Current > Research Centres > Centre for Tropical Crops and Biocommodities
Current > QUT Faculties and Divisions > Science & Engineering Faculty
|Copyright Owner:||Copyright 2012 Elsevier B.V. All rights reserved.|
|Copyright Statement:||This is the author’s version of a work that was accepted for publication in <Polymer Degradation and Stability>. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Polymer Degradation and Stability, [VOL 97, ISSUE 7, (2012)] DOI: 10.1016/j.polymdegradstab.2012.04.004|
|Deposited On:||19 Jun 2012 08:36|
|Last Modified:||19 Jun 2012 10:47|
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