Molecular simulation study of role of polymer–particle interactions in the strain-dependent viscoelasticity of elastomers (Payne effect)

Abstract

The strain-amplitude dependence of viscoelastic behavior of model crosslinked elastomers containing various concentrations of spherical nanoparticles (NPs) was studied by non-equilibrium molecular dynamics simulation. All the filler NPs were in monodispersed state and the interactions between these particles were purely repulsive. The polymer-particle interactions were attractive and their interaction energies were tuned in a broad range. Through the computational study, many important features of the behavior of particle-reinforced elastomers observed in experiments, including the Payne effect, were successfully reproduced. It was shown that the magnitude of the Payne effect was found to depend on the polymer-particle interaction and the filler loading. By examining the microstructures of the simulation systems and their evolution during oscillatory shear, four different mechanisms for the role of the polymer-particle interactions in the Payne effect were revealed that consist of the debonding of polymer chains from NP surfaces, the breakage of polymer-shell-bridged NP network, the rearrangement of the NPs in the network into different layers and the shear-induced yielding of the rigid polymer shell in-between neighboring NPs.

A Coarse-Grained Force Field for Silica–Polybutadiene Interfaces and Nanocomposites

“…The deformation frequency is much higher than those that are commonly employed in experimental studies of filled rubbers, but not so high to produce a glassy response of the polymer (see the results section below). It is in line with those employed in other, current simulation studies of polymer networks and nanocomposites [37,75].…”

“…These system sizes are impressive by current standards, but they still fall short of those required to model the hierarchical organization of the nanoparticles into fractal-like structures, such as those which characterize many rubber nanocomposites [ 33 ]. Thus, most simulations of PNCs are still carried out with coarse-grained (CG) models, typically based on bead-and-spring polymer chains and Lennard–Jones-type (LJ) interaction potentials [ 34 , 35 , 36 , 37 , 38 , 39 ] or some appropriate generalization of them [ 40 ]. An even coarser description is the one based on Dissipative Particle Dynamics (DPD) [ 41 , 42 ].…”

Modeling the Effect of Polymer Chain Stiffness on the Behavior of Polymer Nanocomposites

“…15,16 The dynamics at such small length scales has a remarkable effect on the macroscopic response of the material, including its rheology. The rheological properties of PNCs have been recently assessed in terms of the interactions established between NPs and polymer chains, [21][22][23][24] the nature of the chain attachment to the NP's surface, 25 degree of NPs' dispersion, 26 NP's size 27 and concentration. 28 In particular, in a previous study, we showed that NPs smaller than the R g can reduce the viscosity of the polymer melt and hence act as plasticizers, while particles larger than R g act as thickening agents and significantly increase it.…”

Molecular dynamics simulation of the formation mechanism of the thermal conductive filler network of polymer nanocomposites

“…The calculation method of the heat conduction probability is similar to that of the electrical conductive probability from the simulation work of Feng et al, 54 and it is based on the filler overlapping network as mentioned in our previous studies. 48,55 Note that the dots in Fig. 3c represent the simulation data and the continuous line is the corresponding polynomial smooth curve.…”