Preparation of degradable polypropylene by an addition of poly(ethylene oxide) microcapsule containing TiO2 part II. Modification of calcium phosphate on the TiO2 surface and its effect

To prepare a novel photo-degradable polypropylene (PP) with a higher degradation rate, a PP composite containing a poly(ethylene oxide) (PEO)/modified TiO2 microcapsule was prepared. The modification of the TiO2 was performed by the synthesis of octacalcium phosphate intercalated with succinic acid ion (OCPC) under various Ca/P molar ratio conditions. It was found that the synthesis conditions of the Ca/P = 3.5 and 3.6 M ratios were suitable to prepare the OCPC. However, the microscopic composition on the TiO2 surface was different between these Ca/P conditions and affected the PP photo-degradation rate in the PP/PEO/modified TiO2 composite. It was found from the Fourier Transform Infrared (IR) and the tensile testing measurements that the existence of the OCPC covering material on the TiO2 surface brought about the higher PP photo-degradation rate. The facilitation behavior of the degradation was due to the release of the acid species (succinic acid ion) from the OCPC in the degradation process. In addition, the higher coverage of the OCPC on the TiO2 surface brought about an induction period for the degradation.