A Particle Tracking Velocimetric Study of Interfacial Slip at Polymer–Polymer Interfaces

Abstract

Particle tracking velocimetry (PTV) was used in conjunction with rheological measurements to investigate slip at polymer–polymer interfaces during and after startup shear using simple shear geometry, i.e., a sliding plate rheometer. Polymer pairs include styrene butadiene rubber (SBR) and polyisoprene (PI) of narrow molecular weight distribution, as well as a PI and polydimethylsiloxane (PDMS), with Flory interaction parameter χ ≈ 0.001 and χ ≈ 0.08 respectively. During startup shear, the SBR-PI pair was able to deform without interfacial failure up to a critical strain γ = 2, revealing a level of interfacial strength consistent with thermodynamic considerations. This pair also exhibited arrested interfacial slip after shear cessation for high Weissenberg numbers when the step strain exceeds unity. In contrast, the PDMS–PI interface is much weaker, and slip occurs at γ as low as 0.1. These results shed light on the nature of possible mechanical failure at interphases in multicomponent polymer systems during shear and after shear cessation.

Understanding of Transient Rheology in Step Shear and Its Implication To Explore Nonlinear Relaxation Dynamics of Interphase in Compatible Polymer Multi-microlayered Systems

“…However, for the interphase with entanglement deficiency, in analogy to the PMMA-DMF solutions, the entanglements are very likely to be completely destroyed upon extremely large shears without any re-emergence thereafter, as shown in γ 0 = 3.05 (Figureb). This is in a good accordance with the work of Zartman and Wang, which reported a limitation of interfacial failure at small and intermediate deformations with the broken interface being able to reheal and to sustain the residual shear stress during the last stage of the relaxation whereas at a very large deformation the interphase failed to sustain the imposed stress, as for the interface at an unhealed bilayer.…”

Bulk and Surface Morphologies of ABC Miktoarm Star Terpolymers Composed of PDMS, PI, and PMMA Arms

“…For all calculations, the chain fraction f i = N i /N is assumed to be equal to the volume fraction and N is used to estimate the interaction parameter, χ ij N. ABC miktoarm polymer melts are reported to change morphologies over a narrow range of volume fractions, especially around symmetric composition, which justifies the choice of volume fraction for modeling the system. 29,31 The pairwise interaction parameters were obtained from the studies reported in the literature: χ DM is reported to be ∼0.19 at 150 °C, the annealing temperature used in our work, 12 χ IM is reported to be ∼0.08 at 50 °C69 (assumed to be the same at 150 °C here), and χ ID is reported to be ∼0.08 based on solubility parameter estimation 70 but was found to better fit our observations if a value of 0.0754 was used. Zone annealing was used to equilibrate the system.…”

“…ABC miktoarm polymer melts are reported to change morphologies over a narrow range of volume fractions,especially around symmetric composition, which justifies the choice of volume fraction for modeling the system 29,31. The pairwise interaction parameters were obtained from the studies reported in literature: χDM is reported to be ~ 0.19 at 150 °C, the annealing temperature used in our work,12 χIM it is reported to be ~ 0.08 at 50 °C 69 (assumed to be the same at 150 °C here) and χID is reported to be ~ 0.08 based on solubility parameter estimation,70 but was found to better fit our observations if a value of 0.0554 was used. If a χID value of 0.08 is chosen instead of 0.0554 then[4.8.8] tiling pattern tends to have lower free energy than the experimentally observed [6.6.6] tiling.…”

A Reptation Model of Slip at Entangled Polymer–Polymer Interfaces

“…Several experiments on steady shear flows of multilayer and bilayer films have quantified the relationship between applied shear stress and the velocity of interfacial slip along a single interface. − The results show that slip is a strongly nonlinear phenomena. A nonzero slip velocity is detectable above a threshold shear stress that is set by experimental limits and increases rapidly (much faster than linearly) with increasing stress beyond this threshold.…”