Cyclic carbonic acid esters as solvents for poly-(.beta.-hydroxybutyric acid

Abstract

The use of cyclic carbonic acid esters of the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be the same or different, are hydrogen or alkyl with 1 to 6 C-atoms, as a solvent for racemic or optically active poly-(.beta.-hydroxybutyric acid). The preferred embodiment uses hot (120.degree. to 150.degree. C) ethylene carbonate or 1,2-propylene carbonate to extract poly-(.beta.-hydroxybutyric acid) from moist or dry fermentation masses. These solvents have the advantage that the extracted poly-(.beta.-hydroxybutyric acid) is precipitated in good yield from them on cooling. In addition they may be recycled without the need for a solvent regeneration step. These cyclic carbonic acid esters may also be used as the solvent in the processing of poly-(.beta.-hydroxybutyric acid) by e.g. wet spinning.

Dependencies are inferred from the claim text.