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Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures

Paper ID Volume ID Publish Year Pages File Format Full-Text
33321 44969 2014 12 PDF Available
Title
Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures
Abstract

•PHA biopolymers from mixed microbial cultures contain a broad mix of copolymers.•Differential scanning calorimetry studies demonstrated the presence of blends.•Solvent fractionation studies confirmed this by isolating subfractions.•The crystallisation rate of higher melting fractions is faster than for lower melting.•Mechanical properties will be controlled by crystallisation kinetics and morphology.

Poly[R-3-hydroxybutyrate-co-(R-3-hydroxyvalerate)] (PHBV) copolymers were produced from mixed cultures of biomass (activated sludge) fed with acetic acid (HAc) and propionic acid (HPr). Feeding was performed in such a way as to produce materials with a wide range of monomer compositions and microstructures. Solvent-cast thin films of these materials have recently been shown to exhibit a narrow range of mechanical properties similar to those of the homopolymer poly(R-3-hydroxybutyrate) (PHB) [1]. In this work, more detailed analyses of the thermal and crystallisation properties of these mixed-culture polyesters have revealed that they like comprise complex blends with broad compositional distribution of random and/or blocky copolymers of very different 3-hydroxyvalerate (3HV) contents and melting temperatures and thus have very different respective crystallisation kinetics. This blend complexity was confirmed by solvent fractionation of selected samples. The findings support the hypothesis that overall mechanical properties of these complex copolymer blend materials will be strongly influenced by the more rapidly crystallising components that form the matrix within which the slower crystallising components exist as microdomains. New opportunities in the material development of PHAs are likely to be found in establishing and exploiting such structure–function relationships.

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Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures
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Publisher
Database: Elsevier - ScienceDirect
Journal: New Biotechnology - Volume 31, Issue 4, 25 June 2014, Pages 345–356
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
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Price was $35.95
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