Effect of Filler Particle Size on the Properties of Model Nanocomposites

Abstract

Molecular dynamics simulations have been used to examine the effect of the size of a spherical inclusion in generic model polymer nanocomposite systems. Results are presented concerning the effect of the increasing particle size on the thickness of the interphase, i.e., the perturbed zone of polymer surrounding the inclusion. The behavior of the mass density, molecular orientation, fraction of trans conformers, as well as dynamic properties are presented as a function of the distance from the nanoparticle surface. The effect of temperature on these distributions is also discussed. Long simulations have been carried out to determine the variation in the glass transition of the filled polymers as compared to the pure systems. It is established that, within errors, the interphase thickness is independent of the size of the nanoparticle for the range of particle sizes analyzed. This information is particularly important for the second stage of the project where it is used in continuum micromechanical calculations to try to explain the behavior of the mechanical properties of the model nanocomposites. The confrontation between continuum and atomistic approaches will be the subject of a future publication.

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“…Similar behavior has been observed in molecular dynamics simulations of silica particles dispersed in a polyethylene-like matrix. 43 One of the most important aspects of structure in polymer melts is the so-called "correlation hole" effect . It arises in dense polymeric fluids because of the melt's incompressibility.…”

Local and Global Dynamics in Polypropylene Glycol/Silica Composites

“…Simulations can overcome the problem of the behavior of the interfacial material being swamped by that of the bulk, by enabling a focus on only those chains in proximity to the particles [28,29,30,31,32,33]. Simulations suggest that attraction to the particle surface expands the size of the interfacial chains [34], presumably affecting their motion.…”

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