A polypropylene/high density polyethylene blend compatibilized with an ethylene-propylene-diene monomer block copolymer: Fitting dynamic rheological data by emulsion models with a physical scheme

摘要

The dynamic rheological behaviors at 210, 230, and 250 degrees C are measured by small amplitude oscillatory shear on a rotational rheometer for a polypropylene(PP)/ ethylene-propylene-diene monomer(EPDM) block copolymer/ high density polyethylene (HDPE)/blend. The scanning electron microscope (SEM) photomicrographs show the blend has a droplet/matrix, semi-co-continuous, co-continuous morphology respectively at different weight ratios. The Cole-Cole (G vs. G) data of the blends can be fitted by the simplified Palierne's model only for very narrow weight ratios. A physical scheme is proposed that the dispersed droplets are enclosed by EPDM, thus an equivalent dispersed phase is made up of expanded EPDM. With this physical scheme the G vs. G data of the HDPE-rich blends at 210 degrees C can be fitted well by Palierne's model. Also with the physical scheme the G vs. G data of the PP-rich blends at three temperatures can be fitted well by G-M's model with G* of interface equals to zero. This means the proposed physical scheme is reasonable. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43709.