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Production of Biodegradable Co-Polymers (PHAs) from Biodiesel-Glycerol
About
Biodegradable PHAs have attracted attention for their unique properties as thermoplastics or elastomers due to concerns over environmental pollution caused by relatively recalcitrant plastics and the consumption of fossil fuels for their production. The present technology makes use of glycerol, a byproduct of the biodiesel production process, as a carbon source for its fermentation by a bacterium (Burkholderia cepacia) to produce polyhydroxyalkanoates (PHAs), a class of biodegradable polymers. During the fermentation, levulinic acid is added as a secondary carbon source ultimately resulting in the synthesis of a co-polymer consisting of both butyric acid and valeric acid. After harvesting the bacteria and extracting the PHAs, a nucleating agent (talc) is added at various concentrations to improve certain physical-chemical characteristics, especially crystallization temperature, to enhance performance of these polymers during injection molding. An increase of the crystallization temperature reduces the cooling time of the molten plastic, and assures the shape of the final product. As the aforementioned polymers (PHAs) are synthesized from renewable resources - not petroleum-based feedstocks - the polymers have the characteristics of commodity plastics, especially polypropylene, but are completely degradable to CO2 and H2O. U.S. 8,956,835 SUNY-ESF-1729
Key Benefits
(1) Utilizes a byproduct of the biodiesel industry, glycerol, as the feedstock or starting material for producing biodegradable polymers as substitutes for petroleum-derived plastics, such as polypropylene. (2) The addition of levulinic acid as a secondary carbon source results in the incorporation of valeric acid into the polymer which makes the resulting plastic more flexible as well as less brittle. (3) The combination of a co-polymer (with approximately 30 mole percent valeric acid) and 1-5% talc as a nucleating agent results in a more favorable higher crystallization temperature for producing biodegradable plastics by injection molding.
Applications
Biodegradable plastic production.