Abstract: Hydroxyterminated PHA is produced by cultivating a PHA-producing microorganism in the presence of an aliphatic diol or an aliphatic polyol. High molecular weight hydroxy-terminated PHA is obtainable by the disclosed process, and is useful in the production of graft, block and random polymers and copolymers with other monomers, oligomers and polymers containing appropriate functionality and end group compatibility. The hydroxyterminated PHAs of the invention display improved thermal stability compared with PHAs not modified to contain increased end-group hydroxyl content. In addition, a branched PHA structure is provided by melt processing polyol terminated PHA.

Abstract: Plasticized PHA pellet compositions are provided which are processible into shaped objects, particularly blown and cast free-standing films. The Mw of the PHA in the pellets used to produce the films is at least 470,000, at least 435,000 if PHA thermal stabilizers of the invention are used.