UNIFORM STRETCHING BEHAVIOR OF POLYPROPYLENE FILLED WITH CALCIUM-CARBONATE - STUDIES ON PREPARING OF BIAXIALLY STRETCHED MICROPOROUS POLYPROPYLENE SHEET FILLED WITH WORGAN FILLERS .2.

Polypropylene (PP) filled with calcium carbonate (CaCO3) was extruded to sheets using a T-Die extruder with chill rollers. The effects of several factors on uniaxial stretching uniformity at three times stretching were investigated. These factors included CaCO3 content, CaCO3 particle size, kinds and contents of dispersing additives, and preliminary low ratio stretching at low temperature. (1) With increasing CaCO3 content, the uniform stretching temperature range is elevated. Smaller fillers need higher content of dispersing additives. (2) The nonionic surfactant content of 0.05 approximately 0.07 g/m2.CaCO3 is effective for improving uniform stretching ability. (3) Adipic acid, a polyester plasticizer, enhances uniform stretchability. (4) Dispersing additives aid CaCO3 to disperse in the PP matrix. The boundary of PP/CaCO3 is peeled under the stretching stress, by this uniform stretching is achieved. (5) Preliminary low ratio stretching at low temperatures is more effective than mormal high ratio stretching at high temperature.