3D numerical analysis of mass diffusion in (nano) composites: the effect of the filler-matrix interphase on barrier properties

Abstract

Polymer nanocomposites based on impermeable fillers have been widely developed to improve gas barrier properties. These materials have to be viewed as three phase systems: the matrix, the fillers and an interphase layer between the filler and the matrix. In this paper, the effect of the interphase layer on the overall diffusivity of nanocomposites loaded with impermeable disk-like fillers is analyzed and quantified through 3D finite element modeling of mass diffusion. Ideal ordered filler distributions as well as random filler distributions are considered for filler content in the range 1–20 vol%. A parametric study covering interphase thickness to filler thickness ratio values between 0.125 and 0.5 and interphase diffusivity ratio D interphase/D matrix values from 10−4 to 106 is presented and discussed. The results show that, depending on their quality (weakly or highly diffusive), the presence of interphases can be either beneficial or totally detrimental to the nanocomposite overall barrier properties. A specific case corresponding to the exact compensation of the tortuosity effect by the diffusion in the interphase layer is evidenced and analyzed. Moreover, the effect of continuous diffusion paths, which may occur between overlapping interphases, is investigated. This effect appears to be particularly critical for the barrier performance in the case of highly diffusive interphases. Finally, a confrontation between our simulation approach and an analytical model as well experimental data is proposed.

3D Modelling of Mass Transfer into Bio-Composite

“…This typical impact of the presence of interphases on mass transfer within composites has already been observed by Zid et al [ 22 ] for nanocomposite with impermeable fillers and by Petsi and Burganos [ 21 ] in mixed matrix membranes. Zid et al [ 22 ] noticed that the interphase layers, depending on their diffusivity (weakly or highly diffusive) can be either beneficial or totally detrimental to the nanocomposite overall barrier properties.…”

“…This typical impact of the presence of interphases on mass transfer within composites has already been observed by Zid et al [22] for nanocomposite with impermeable fillers and by Petsi and Burganos [21] in mixed matrix membranes. Zid et al [22] noticed that the interphase layers, depending on their diffusivity (weakly or highly diffusive) can be either beneficial or totally detrimental to the nanocomposite overall barrier properties. They particularly highlighted the impact of the effect of continuous diffusion paths, which may occur between overlapping interphases, that are particularly critical for the barrier performance in the case of highly diffusive interphases.…”

“…In the previous cited works whether analytical or numerical ones, the presence of an interphase at the particle/matrix interface which exhibit mass transfer properties differing substantially from those of the bulk matrix is always neglected. Role of this interphase is of paramount importance which can lead to a percolating interphase network inside of the composite, as highlighted by Qiao and Brinson (2009) [20] or Petsi and Burganos (2012) [21] in mixed-matrix membranes and by Zid et al [22] on nanocomposites with impermeable fillers. Aforementioned studies of Qiao and Brinson and Petsi and Burganos proposed a two-dimensional numerical model to study the impact of interphase zones on the overall properties of the composites (mechanical properties for Qiao and Brinson and effective permeability for Petsi and Burganos).…”

Finite Element Analysis of Gas Diffusion in Polymer Nanocomposite Systems Containing Rod-like Nanofillers

“…A number of models describing the interphase’s influence on transport properties are available in the literature. Such models are based on geometrical and analytical approaches [ 8 , 66 , 67 , 68 ] or numerical approaches, mainly at the mesoscale using FEM [ 42 , 69 ] or at smaller scales using molecular dynamics [ 70 , 71 , 72 , 73 , 74 ]. FEM-based models basically consider the interphase as a third medium (or phase) surrounding the fillers, with well-defined boundaries and homogeneous diffusion properties.…”

“…A modeling methodology similar to that applied for disk-like fillers by Zid et al [ 41 , 42 ] was implemented. A three-dimensional parallelepipedic representative volume element (RVE) was chosen to model the geometry of the nanocomposite in a Cartesian coordinate system ( x , y , z ), with z being the axis parallel to the overall diffusion direction.…”