Mechanistic Model for Deformation of Polymer Nanocomposite Melts under Large Amplitude Shear

TL;DR

This paper presents a mechanistic model explaining the nonlinear deformation behavior of poly(styrene)-silica nanocomposites under large amplitude shear, highlighting particle and polymer network responses and chain stretching effects.

Contribution

It introduces a novel mechanistic model that captures particle and polymer deformation at various strains, aligning chain stretching with nonlinear polymer network theory.

Findings

Elastic stress decomposition reveals particle and polymer contributions.

Chain stretching in nanocomposites agrees with nonlinear chain deformation theory.

Model accurately describes deformation behavior at different strain levels.

Abstract

We report the mechanical response of a model nanocomposite system of poly(styrene) (PS)-silica to large-amplitude oscillatory shear deformations. Nonlinear behavior of PS nanocomposites is discussed with the changes in particle dispersion upon deformation to provide a complete physical picture of their mechanical properties. The elastic stresses for the particle and polymer are resolved by decomposing the total stress into its purely elastic and viscous components for composites at different strain levels within a cycle of deformation. We propose a mechanistic model which captures the deformation of particles and polymer networks at small and large strains, respectively. We show, for the first time, that chain stretching in a polymer nanocomposite obtained in large amplitude oscillatory deformation is in good agreement with the nonlinear chain deformation theory of polymeric networks.