Elastomeric compositions with improved resistance to necking for high speed sheet extrusion applications

摘要

A composition comprising: (a) a high melt strength material, comprising a first polymer selected from the group consisting of an elastomeric ethylene/α-olefin polymer and a polypropylene polymer, and (b) a high flow material, comprising a second polymer selected from the group consisting of an elastomeric ethylene/α-olefin polymer and a polypropylene polymer. The high melt strength material has a dynamic complex viscosity greater than, or equal to, 175,000 Poise (17,500 Pa-s), measured using parallel plate rheometry at 1 radians per second and 190 degrees Centigrade, and the high flow material has a ratio, η*/td, less than 2500, where η* is the dynamic complex viscosity and td is the tan delta, both measured at 1 radian per second at 190 degrees Centigrade. The composition exhibits minimal necking when extruded at high speeds and is particularly useful for making sheets via high speed extrusion.