ABSTRACT
Microbial polyesters such as polyhydroxybutyrate and its copolymers with hydroxyvalerate are an interesting class of degradable polymers [ 1 ] which is receiv ing increasing attention in the biomedical field. Because of the absence of specific enzymes, the in-vivo degradation of these materials is claimed to occur by chemical hydrolysis due to the presence of water molecules in the body fluids [1]. Some authors have reported evidence of degradation [2-10] while others have described PHBV as nondegradable [11]. Recent work [12] showed good tolerance of PHBV copolymers inplanted in rats with a degradation of about 40% after 6 months; the reduction of molecular weight was faster for systems with a high content of hydroxyvalerate.
