Influence of Stereoregularity on the Wall Slip Phenomenon in Polypropylene

Abstract

Thus, although a lot is now known about themechanisms of the interfacial slip, it is still not clearas to how the subtleties of molecular architectureinfluence the slip behavior. Thus, the effects of molec-ular structural parameters such as molecular weight,molecular weight distribution, tacticity, short- and long-chain branching, and the branching distribution are stillnot completely understood. In this work we show for thefirst time that the tacticity of polymer chains cansignificantly influence the slip behavior. We show thatsyndiotactic polypropylene shows sharkskin distortionson the extrudate surface, which is an indication of wallslip, while an isotactic polypropylene of similar molec-ular weight and molecular weight distribution does notshow any wall slip.