Accelerated degradation of highly loaded polypropylene

The accelerated aging of six formulations of polypropylene highly loaded with calcium carbonate and containing a surfactant additive (stearic acid) as well as an ultraviolet (UV) stabilizer was studied. Degradation was followed by measuring mechanical properties (elongation percentage and impact resistance), the dynamic mechanical behavior and some chemical changes such as molecular weight and carbonyl group formation along with oxidation temperatures, found by chemiluminescence. The addition of 30 phr of filler to the polymer reduced the stability of the mixture, and the stearic acid used to treat the filler enhanced this effect considerably. On the other hand, the addition of the photostabilizer controlled to some extent such negative effects. though not completely. The most stable formulation was the polypropylene containing only the LJV stabilizer.