On the biodegradation of poly-beta-hydroxybutyrate (PHB) homopolymer and poly-beta-hydroxybutyrate-hydroxyvalerate copolymers.

The known biodegradability of PHB in certain biological environments has led to its proposed use as a 'biodegradable' implant material. Monofilaments of PHB homopolymer and two PHV-PHB copolymers have been studied in vivo and in vitro and assessed for changes in mechanical properties and topography. In vivo biodegradation was only observed with PHB when pre-degraded by 10.0 Mrad of gamma-irradiation before implantation. High temperature in vitro hydrolysis suggested that PHV copolymer additions retarded the rate of degradation of PHB. Hydration reactions had most effect on the ultimate tensile properties of the materials. In contrast, the elastic properties appeared to be relatively unaffected.