長鎖分岐ポリプロピレンを分散相とするポリオレフィンブレンドのレオロジー特性

抄録

Rheological properties for binary polyolefin blends composed of linear low-density polyethylene (LLDPE) and long-chain branched polypropylene (LCB-PP), in which LCB-PP is the dispersed phase, were studied. Even though LCB-PP was in the dispersed phase, the blend showed marked strain-hardening behavior in the transient elongational viscosity. The deformed LCB-PP droplets acted as “rigid fibers” during the elongational flow owing to its strain-hardening behavior. Consequently, the blend behaved like a fiber-dispersion system and thus exhibited the enhanced elongational viscosity, originated from excess deformation of LLDPE located between fibrous LCB-PP droplets under the elongational flow. Under shear flow, the primary normal stress difference was not enhanced by the addition of LCB-PP. This is reasonable because LCB-PP droplets oriented to the flow direction did not provide excess deformation of a continuous phase greatly.