The biodegradation behaviors of poly(p-dioxanone)/organo-montmorillonite (PPDO/OMMT) nanocomposites were investigated in an aqueous medium with spores of selected culture microorganisms at 28℃ for 90 days.The degradation of samples was characterized by mass loss

intrinsic viscosity variation

pH value

DSC and SEM.The results showed that the biodegradation rates of nanocomposite increased with the increase of OMMT contents.After 90 days degradation

the weight losses of pure PPDO and PPDO/5% OMMT nanocomposite in the aqueous medium with and without spores of selected culture microorganisms were 17.9%

28.4%

and 12.9%

18.0%

respectively.The biodegradation of PPDO/OMMT was mainly related to the hydrolysis degradation and was improved by selected culture microorganisms.During 30 days of degradation

the intrinsic viscosity of PPDO/OMMT nanocomposites decreased significantly and their weight losses increased slowly as a consequence of the random break of ester bonds in PPDO long chains.As the biodegradation proceeds

many kinds of water-soluble products such as organic acids and oligomeric acids were produced.Therefore

the pH value of aqueous medium decreased and the weight losses increased obviously with the progress of biodegradation.The biodegradation of samples occurred preferentially in the amorphous areas

leading to the increase of crystallinity.As the biodegradation time increased

the crystalline regions were attacked

which caused the decrease of crystallinity.After biodegradation

the remarkable erosion was found on the surface of PPDO due to the bio-erosion of microorganism.However

no remarkable cracks emerged on the surface of PPDO/5% OMMT nanocomposite

which was assigned to the interaction and adhesion of PPDO and OMMT.