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CHAPTER 2

Polyhydroxyalkanoates: Structure, Properties and Sources

Economic and environmental concerns have driven the development of biobased polymers and materials in recent years. The PHAs family was not the main focus of studies for decades, however, this class of polymers has been gaining scientific and industrial interest. The variety of polymers that make up the PHA family—more than 150—is due to different producers and carbon sources. The most studied producers of short-chain length PHAs (PHASCL) are the microorganisms of the Cupriavidus genus, however, recent developments in the field of mixed cultures have also produced interesting results. An important point is that whatever the carbon source, the PHASCL producing organism will produce these biopolymers; this has allowed an extensive study of noble and waste carbon sources, usage of limiting factors and of nutrient-sufficient media. On the other hand, the structure of medium-chain length PHAs (PHAMCL) is intimately related to the carbon source used for the growth of the producing organism and the biopolymer accumulation. Also the properties of this family are very wide, ranging from brittle thermoplastic PHASCL to elastomeric PHAMCL. These properties can be triggered by post-fermentation modifications such as grafting, surface treatment etc., to reach the necessary thermo-chemical constraints. Finally, the biocompatibility of PHAs, influenced by their structure, makes them extremely interesting candidates for biomedical applications. This new market has specific constraints, which can influence the choice of the initial carbon source. The relationships between sources, structure and properties of different types of PHAs are discussed in this chapter.

Print publication date: 12 Nov 2014
Copyright year: 2015
Print ISBN: 978-1-84973-946-7
PDF eISBN: 978-1-78262-231-4
ePub eISBN: 978-1-78262-328-1
Citation:
From the book series:
Green Chemistry Series