Enhancement of Strain-Hardening in Elongational Viscosity for Linear Polymers
Masyauki Yamaguchi
TOSOH Corporation
Japan

Keywords: Foam, Elongational Viscosity, polymer blend

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Blending a small amount of a crosslinked polymer enhances the strain-hardening in elongational viscosity of linear polymers, such as polyethylene and polypropylene, when the following conditions are satisfied: (1) The crosslinked polymer has a network chain with a low density of crosslink points; (2) The precursor of the crosslinked polymer is miscible with the linear polymer. Moreover, melt elasticity, such as extrudate swell and primary normal stress difference, is also enhanced by blending the crosslinked polymer, whereas the blend shows similar steady-state shear viscosity to the linear polymer. The origin of the anomalous rheological properties will be due to chain stretching of network polymers via trapped entanglements with a linear polymer. The blends having enhanced melt elasticity exhibit excellent processability for various processing including foaming.