RHEOLOGICAL PROPERTIES FOR BINARY BLENDS OF I-PP AND ETHYLENE-1-HEXENE COPOLYMER

The dynamic viscoelastic properties for binary blends consisting of an isotactic polypropylene (i-PP) and an ethylene-1-hexene copolymer (EH R) were investigated in both solid and molten states to reveal the rel ation between miscibility in the molten state and the morphology in th e solid state. In this study, two types of EHRs were employed: ''ethyl ene-rich'' EHR and ''1-hexene-rich'' EHR. The blend of i-PP and EHR of 30 mol% 1-hexene content shows a very long time relaxation due to the phase separation in the molten state. The blend film shows two separa te glass-relaxation processes associated with those of the pure compon ents. These indicate that the blend shows phase-separated morphology i n the solid state as well as in the molten state. On the other hand, d ynamic moduli in the molten state of the blends of i-PP and EHR of 57 mol% 1-hexene were found to be intermediate between those of individua l pure components. Furthermore, the apparent activation energy of the blends is constant and is identical with those of i-PP and the EHR. Th e blend films show a single glass-relaxation process at the temperatur es between those of the pure components, indicating that the EKR molec ules are incorporated in the amorphous region of i-PP in the solid sta te. Accordingly it was found that the polymer miscibility in the molte n state for the i-PP/EHR blends directly affects the morphology in the solid state. (C) 1997 John Wiley & Sons, Inc.