SOLID-STATE PROCESSING OF PHB-POWDERS

Poly(3-hydroxybutyrate) (PHB) is a completely biodegradable polyester, produced by bacterial fermentation. Because of poor thermal stability , melt processing of the material is accompanied by thermal degradatio n and poor mechanical properties. To prevent thermal degradation, a so lid-state processing technology has been applied. The extrusion of PHB -powder at temperatures far below the melting point leads to products of improved mechanical properties. In particular. the ductility of the material increases considerably compared to traditional melt processe d PHB. The improved mechanical properties have been attributed to stru ctural differences on the molecular and supermolecular level.