| abstract |
Polyhydroxyalkanoate (PHA) polyester is extracted from biomass by dissolving the PHA in a non-halogenated solvent which comprises a PHA-good solvent or a mixture thereof. Suitable PHA-good solvents can be selected from the disclosed alcohols, esters, amides and ketones. The PHA can be recovered, for example, by cooling, by solvent evaporation, or by addition of a PHA-poor solvent, wherein the PHA-poor solvent preferably dissolves less than about 1 % (w/v) of the PHA at a temperature below the solvent boiling point. Preferred PHA types for use in the invention are poly(hydroxybutyrate-co-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and polymers/copolymers of hydroxyterminated polyhydroxybutyrate. |