Study on biodegradation mechanism of novel oxo-biodegradable polypropylenes in an aqueous medium

In this work, the biodegradation behavior of the polypropylene (PP)/poly(ethylene oxide) (PEO)/TiO2 and the PP/PEO/TiO2/octacalcium phosphate intercalated with succinic acid ion (OCPC) composites was studied. The photodegraded PP/PEO/TiO2 sample was mineralized up to ca. 10% after the respirometric biodegradation test for 80 days, and the specimen (20 × 5 mm) was biodegraded to a small piece (ca. 3 × 3 mm). The molecular weight was decreased by the biodegradation as well as the photodegradation, suggesting that not only the low molecular weight oxidation products but also the oxidized PP matrix were biodegraded. The result of the 1H NMR measurement indicated that the biodegradation occurred anaerobically. The photodegraded PP/PEO/TiO2/OCPC sample was mineralized up to ca. 20% after the test for 80 days. The specimen (20 × 5 mm) was biodegraded to a very small piece (ca. 40 × 20 μm). The acceleration of the mineralization rate was observed at between the 30 and 50 days in the test. As the PP matrix was biodegraded, the contained OCPC was released to the solvent surroundings. The dissolved succinic acid contaminated them and initiated the aerobic biodegradation leading to the increase of the mineralization.