Effect of Treated Calcium Carbonate on Mechanical Properties of Polypropylene

Mechanical properties (breaking elongation) and efflux rate of polypropylene (PP) were improved by filling it by calcium carbonate treated with phosphate coupling agent. Improvement of mechanical properties (breaking elongation) and efflux rate was attributed to polymer-filler adhesion by means of the phosphate coupling agent phase causing the reduction of the stress concentration and lubricant at polymer-filler interface. In the case of untreated calcium carbonate, relative modulus (Er) increased with an increase of volume fraction (φ2). For the treated calcium carbonate, however, Er decreased with an increase of φ2, at 3.4 vol% of phosphate coupling agent for calcium carbonate. PP filled with the treated calcium carbonate showed larger loss-tangent (tanδ) than PP filled with untreated calcium carbonate. The increment of tan δ was satisfactorily estimated from φ2 of calcium carbonate.