Direct and indirect polymer-polymer interfacial slip measurements in multilayered films

Patrick C. Lee, Hee Eon Park, Christopher W. MacOsko

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Significant slip can occur during flow of two immiscible polymers due to reduced entanglements at their interface. The slip is of practical importance because of its effect on morphology and adhesion of these multi-phase materials, such as disordered two-phase blends and multilayer films. In this research, we are investigating the amount of polymer-polymer slip over a range of shear stresses from rheological measurements (i.e., indirect method) and visualization measurements (i.e., direct method) on co-extruded multilayer films. Two types of alternately layered blends were chosen: polypropylene (PP)/polystyrene (PS) and polyethylene (PE)/fluoropolymer (FP) blends. The multilayer samples of both PP/PS and PE/FP blends were prepared in a co-extrusion setup (Zhao and Macosko J. Rheol. 2002) at 200 and 210°C, respectively, in order to match viscosity and linear viscoelasticity. To study the polymer-polymer interfacial slip over a wide stress range, three types of rheometers were used: an in-line slit-die rheometer, a rotational parallel-disk rheometer, and a sliding-plates rheometer (SPR). It was observed that the viscosity of a multilayer sample is lower than the harmonic average viscosity of two neat polymers for both PP/PS and PE/FP and decreases with the number of layers above a certain critical shear stress. Two visualization techniques, (i) the SPR with a glass top plate and (ii) a high temperature shearing cell, were utilized to prove the slip. The slip velocity (i.e., the amount of macroscopic velocity discontinuity at the interface) with respect to shear stress was calculated from each rheological and visualization methods and compared.

Original languageEnglish (US)
Title of host publicationThe XVth International Congress on Rheology - The Society of Rheology 80th Annual Meeting
Number of pages3
StatePublished - Sep 11 2008
Event15th International Congress on Rheology - Monterey, CA, United States
Duration: Aug 3 2008Aug 8 2008

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Other15th International Congress on Rheology
CountryUnited States
CityMonterey, CA


  • Immiscible blends
  • Slip
  • Visualization

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