Novel Ethylene/Alpha-Olefin Copolymer - Polypropylene Blends for Automotive Thermoformed Sheeting Applications

摘要

Ethylene/alpha-olefin copolymer -polypropylene (PP) blends are among the options now available to manufacturers of automotive interior sheeting used in negative and positive pressure thermoforming. The melt strength characteristics and other associated physical properties of sheeting produced from such blends are similar to previously introduced blends of ethylene/1-octene and PP, which have been reactively modified by peroxide during compounding. The enhanced melt strength required for thermoforming is a feature made possible via patented reactor based technology introduced by DuPont Dow Elastomers L.L.C. during the past year that includes unique ethylene/alpha olefin copolymer grades with enhanced levels of long chain branching, broader molecular weight distributions (MWD), and higher molecular weights. Sheeting can be produced from pre-compounded blends or via inline blending of the high melt strength elastomers and PP using either Banbury mixers employed in calendering or an appropriate single or twin screw extruder used for extrusion. This paper compares sheeting produced via in-line compounding and from conventional extruded compounds, both, which utilize elastomer rich blends with PP. The sheeting is compared on a performance basis to a soft TPO compound that was produced via reactive extrusion for automotive interior sheeting aimed at instrument and door panels.