TOUGHENED MICA-FILLED POLYPROPYLENE SYSTEMS

A family of rubber-toughened, mica-filled polypropylene materials was developed. The rubber modifier used was an ethylene-propylene-diene monomer (EDPM) compound. A unique feature of this rubber-modified system is that it can be directly molded from a dry blend. This simplifies processing by eliminating the need for melt compounding which, in turn, contributes to greater flexural moduli since attrition of the mica platelets is reduced. In addition, impact measurements were conducted as a function of temperature for EPDM/polypropylene and EPDM/poly(propylene-ethylene) copolymer blends. The low temperature impact resistance was improved for both systems, however, the modified copolymer system maintained ductile behavior to a far lower temperature than the corresponding homopolymer system.