title: Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures.
abstract: 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.
authors.affiliation: School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia. Electronic address: b.laycock@uq.edu.au.
authors.forename: Bronwyn
authors.initials: B
authors.lastname: Laycock
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, SE-226 47 Lund, Sweden.
authors.forename: Monica V
authors.initials: MV
authors.lastname: Arcos-Hernandez
authors.affiliation: School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Langford
authors.affiliation: School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Pratt
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, SE-226 47 Lund, Sweden.
authors.forename: Alan
authors.initials: A
authors.lastname: Werker
authors.affiliation: School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Halley
authors.affiliation: School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Lant
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D002152:Calorimetry, Differential Scanning; D005591:Chemical Fractionation; D003460:Crystallization; D008853:Microscopy; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis* / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry; D013696:Temperature
chemical_list: D054813:Polyhydroxyalkanoates; D012997:Solvents