Biocomposites from waste-derived polyhydroxyalkanote (PHA): Mixed culture generation of polyhydroxybuturate-co-valerate (PHBV) copolymers and their inclusion in wood plastic composites

International Conference and Exhibition on Biopolymers & Bioplastics

August 10-12, 2015 San Francisco, USA

Steven Pratt1, Alexandra Langford1, Des Richardson 2, Alan Werker 3, Monica Arcos3, Peter Halley1, Paul Lant1 and Bronwyn Laycock1

Scientific Tracks Abstracts: J Material Sci Eng

Abstract :

Polyhydroxyalkanote (PHA) bioplastics have properties similar to polypropylene and PET, and are therefore outstanding
candidates to replace some fossil fuelderived materials. Moreover, being both bio-based and biodegradable, PHAs allow
for a closed loop carbon cycle and, unlike many other biomaterials on the market, they are both water resistant and UV
stable. However, PHA is relatively expensive. This can be somewhat addressed by (i) producing PHA in open mixed microbial
cultures using waste organic carbon as the feedstock, and (ii) compounding the polymer with fillers like wood flour; the use
of wood flour in plastics is attractive for many reasons: it is abundantly available, biodegradable and low cost. This work
lays a foundation for the development of high performance PHA-based wood plastic composites. The paper presents the
compounding of commercial poly-(hydroxybutyrate-co-valerate) (PHBV) with low HV content (5%), with pine flour (300
μm and 550 μm). A range of PHA to wood flour ratios was considered. The mechanical properties (toughness and elongation
to break), thermal behaviour and morphology of the produced materials were analysed, as was the water permeability. A
preliminary analysis of the effect of surface modification on these properties was undertaken. The results are a benchmark
for new Biocomposites from HV-rich, waste-derived PHA. Our recent research shows that industrially relevant PHA can be
readily synthesised in mixed cultures, which can utilise cheap and renewable carbon sources such as waste streams from the
pulp and paper industry. This, coupled with the innovative approach of making direct use of PHA-rich intact cells in wood fibre
composites, thereby avoiding PHA extraction, means the PHA based materials could be cost-competitive with alternatives.
Further, it is suspected that HV-rich mixed culture PHA will lead to good melt flow and hence effective contact between
wood fibre and the biopolymer, as well as enable lower processing temperatures than are necessary for PHB based materials,
thereby reducing thermal degradation and energy costs. Also, the concept overcomes a perceived limitation of PHA since the
wood fibres act as nucleating agents for rapid crystallisation thereby circumventing the material stability issues associated with
secondary crystallisation.

Biography :

Steven Pratt is a senior lecturer in the School of Chemical Engineering at the University of Queensland. The theme of Steven Pratt research activities broadly
encompasses Biorefining and the development of sustainable biomaterials. Steven Pratt currently lead Australian Research Council (ARC) funded projects on
developing novel PHA wood composites, generating PHA from methane, and managing algae harvested from coal seam gas water. Steven Pratt major contribution
to the field of environmental biotechnology is the invention of the TOGA Sensor for examination and control of biotech/bioprocess systems; The TOGA Sensor is a
platform for world-class research and it has been a key tool for many PhD projects.