Implicit Medium Model for Fractal Aggregate Polymer Nanocomposites: Linear Viscoelastic Properties - Archive ouverte HAL Access content directly
Journal Articles Macromolecules Year : 2019

Implicit Medium Model for Fractal Aggregate Polymer Nanocomposites: Linear Viscoelastic Properties

Abstract

Dispersing solid fillers into a polymer matrix is a common strategy to enhance and tailor its properties. The polymer nanocomposites so obtained with fractal-like aggregates have exceptional rheological behavior that have long been exploited in the tire industry. However, due to the disparity of time and length scales, our understanding of the relation between nanocomposites structure and rheology remains far from complete. We propose in this work a mesoscopic model to address the dynamics and the rheology of aggregate nanocomposites. While aggregates are represented explicitly as groups of interacting particles, we use for the polymeric matrix an implicit description based on generalized Langevin and Stokes equations, that captures the average effect of a viscoelastic medium. These two-level modelling allows us to simulate large systems containing dozens of aggregates. Focusing here on the linear viscoelastic properties of PNCs, we characterize the influence of aggregate size, volume fraction, rigidity and polydispersity. We demonstrate that rigid aggregates systems display salient features of the phenomenology of PNCs, namely slow relaxation in the stress relaxation response, non-Maxwell elastic response at low frequency and supralinear dependence of their storage modulus with volume fraction. We also point out the critical role played by aggregate rigidity, and show that for either flexible aggregates or well dispersed nanofillers, the effects are far less spectacular. Our findings should help in designing nanocomposites with enhanced mechanical properties.
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Dates and versions

hal-03035309 , version 1 (05-12-2020)

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Yang Wang, Gaëtan Maurel, Marc Couty, François Detcheverry, Samy Merabia. Implicit Medium Model for Fractal Aggregate Polymer Nanocomposites: Linear Viscoelastic Properties. Macromolecules, 2019, 52 (5), pp.2021-2032. ⟨10.1021/acs.macromol.8b02455⟩. ⟨hal-03035309⟩
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