Multilayer rheology: A comparison of experimental data with modeling of multilayer shear flow

Abstract

The rheological behavior of multilayer polyjeric structures has been investigated Measurements of the bulk viscoelastic properties via small‐amplitude oscilatory rheometry indicated that the shear viscosity is independent of both the numbe of layers (83 vs. 165) and the composition (30/70, 50/50, and 70/30 PC/PMMA by weight) within the limits of the data obtained. It is also apparent tha tthe shear viscosity is influenced strongly by the skin layer material. In additon, a model has been developed tha tcan be used to proedict the shear viscosity and shear stress ofa multilayer structure experiencing shear flow. The model predicts tha thte shear viscosity of a multilayer structure should be independent of the number of layers and strongly dependent on the material in the skin layer. These predictions are in agreement with experimental data.

Nanorheology with a Conventional Rheometer: Probing the Interfacial Properties in Compatibilized Multinanolayer Polymer Films

“…At high frequencies this interphase viscosity then roughly joins this of the bulk, in agreement with the Cohen et al 55 measurement of the effective viscosity of sheared polydimethylsiloxane (PDMS) brushes with different molecular weights. However, this relation does not adjust the rheological behavior of such multilayer films in the presence of an interphase, and many authors suggest the introduction of a third phase (in serial) for noncompatibilized 54 or compatibilized systems, 52 or interfacial slip velocity. 19 However, there is no interfacial slip evidence in the compatibilized system, according to Zhao and Macosko.…”

“…The complex viscosity η* of immiscible multilayer films is generally described by a serial model (eq ) considering no interaction between phases: ,− where ϕ PE–PEgMA and ϕ PA6 are the volume fractions of PE and PA6 phases and η*­(ω), η* PE–PEgMA (ω), and η* PA6 (ω) correspond to the apparent complex viscosity of the multilayer film, PE–PEgMA and PA6 layers (or phases), respectively. Because η* PA6 ≫ η* PE–PEgMA , the second term of (3) can be neglected.…”

“…However, this relation does not adjust the rheological behavior of such multilayer films in the presence of an interphase, and many authors suggest the introduction of a third phase (in serial) for noncompatibilized or compatibilized systems, or interfacial slip velocity . However, there is no interfacial slip evidence in the compatibilized system, according to Zhao and Macosko .…”

Modeling of the rheological properties of multinanolayer films in the presence of compatibilized interphase

“…For readability, the shear dependent viscosity η*(ω) will be written η* in the following. In shear rheology, a serial model (addition of velocity gradient dV and shear stress τ constant over all film thickness z) has to be considered to predict the apparent complex viscosity η* of multilayered films [17,27,32,33]. For a small thickness variation dx, the velocity variation dV is related to the constant shear stress τ…”

Flow Accelerates Interfacial Coupling Reactions

“…This result contradicts that reported by Kim and co-workers for a PS-COOH and PMMA-GMA (glycidyl methacrylate) bilayer, where dramatic increase in viscosity was observed when the bilayer was subjected to a small-amplitude dynamic shear. − They argued that the increase was caused by the rough interface induced by the coupling reaction. Obviously, that was not the case for PS-NH 2 /PMMA-anh. The viscosity of a layered sample (for example a bilayer) can be calculated from the viscosity and thickness of each layer with eq h normalη = h 1 normalη 1 + h 2 normalη 2 where η i and h i are the viscosity and thickness of the layers, respectively.…”