Relation between mechanical response of reinforced elastomers and dynamics of confined polymer chains

Elastomers used in everyday life are always reinforced with rigid nanoparticles (carbon black or silica). The addition of rigid nanoparticles to an elastomer gives it very specific viscoelastic properties. In this article, we discuss the current understanding of mechanical properties of a polymer matrix around its glass transition, focusing on the situation of polymers confined between two rigid surfaces with a nanometric gap. Then, we will explain how the properties of the matrix can help to understand the properties of filled or reinforced elastomers. We will then explain that in reinforced rubbers, the mechanical properties are dominated by stress propagation between neighboring aggregates through a nanometric polymer gap, thus by confined polymer bridges. We will discuss how knowledge of the dynamics of confined polymers allows us to understand the temperature dependence, the pressure dependence and the non-linearities observed for strain below 0.1 of reinforced elastomers.