Preparation of degradable polypropylene by an addition of poly(ethylene oxide) microcapsule containing TiO2. Part III: Effect of existence of calcium phosphate on biodegradation behavior

In this work, biodegradation behavior of a novel polypropylene (PP) composite containing a poly(ethylene oxide) (PEO)/modified TiO2 microcapsule was studied with an oxo-biodegradation test combined with a photodegradation treatment (using a high-pressure mercury vapor lamp for 24 h of the irradiation at 30 °C in air) and a soil burial test (for 45 days of incubation at 20 °C). The modification of the TiO2 was performed by the synthesis of octacalcium phosphate intercalated with succinic acid ion (OCPC). The existence of the microcapsule brought about higher PP photo- and biodegradation rates. In the photodegraded PP composite, active colonies of some microorganisms were observed. By comparing with the PP composite without the OCPC modification, it was found that the active behavior of the microorganisms was due to the inorganic phosphates, which were supplied by the dissolution of the OCPC during the photodegradation. In addition, the photodegraded parts in the composite were completely metabolized by the microorganisms. However, the microorganisms had the inability to metabolize other parts such as the PP crystalline phase.