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

Abstract

The dynamic rheological behaviors at 210, 230, and 250 8C 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-cocontinuous, co-continuous morphology respectively at different weight ratios. The Cole-Cole (G 00 vs. G 0 ) 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 00 vs.G 0 data of the HDPE-rich blends at 210 8C can be fitted well by Palierne's model. Also with the physical scheme the G 00 vs. G 0 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.

Rheological characterization of compatibilized polymer blends

“…Even if Palierne [18] is the most popular emulsion model based on linear viscoelastic behavior of polymer blends [11,19,20], there are other emulsion models such as Choi and Schowalter (for semidilute emulsions of Newtonian liquids) [21e23], Oldroyd's [24], Bousmina's [25], but also Lee and Park's model, Gramespacher and Meissner's model (simply named GeM's model) [26,27]. The GeM's model for example considers that the viscoelastic properties of the blend are constituted of the complex shear modulus of the components and that of the interface.…”

A Polymethylvinylsiloxane/Low Density Polyethylene Blending Melt: Dynamic Rheological Behavior and Relaxation Time

“…The emulsion-in-emulsion morphology became visible when PA6 content was high, for example, the ternary blend with PP/PP-g-MAH/PA6 was 35/35/30. In our recent work [10], a polypropylene(PP)/ high density polyethylene(HDPE) blend compatibilized with an Ethylene-Propylene-Diene Monomer block copolymer(EPDM) has similar morphology and rheology. This emulsion-in-emulsion structure is in fact the so-called "core-shell".…”