Degradation of Polypropylene Filled with CaCO3 in Weathering Test

The degradation of polypropylene filled with CaCO3 in 25 vol% by weathering test was investigated. The following results were obtained: (1) The izod impact value and tensile elongation of the molded samples filled with CaCO3 in 25 vol% were reduced by half after exposure for less than 100 h, and the degradation was accelerated by filling with CaCO3. (2) The magnitudes of the changes in the various mechanical properties by exposure were similar to those in thermal degradation, but photo degradation of molded samples filled with CaCO3 was less affected by small quantities of impure metals in CaCO3, for example, Fe, Cu, Mn, Al, comparing with thermal degradation. (3) The antioxidant, thio-propionate, was effective as an inhibitor for degradation, and the effect was improved when used together with the ultraviolet rays absorbent, such as benzotriazol compound. (4) Molded smaples were degraded from the surface layer, as revealed by the IR absorption spectra and the observation of fracture surfaces.