Simulation of polymer melt intercalation in layered nanocomposites

Abstract

In situ rheo-x-ray investigation of flow-induced orientation in layered silicate-syndiotactic polypropylene nanocomposite melt Polymer layered silicates form an important class of nanocomposite materials. These structures may be formed by annealing layered silicate particles, whose surfaces have been chemically modified to render them organophilic, with a polymer melt. During intercalation, polymer molecules leave the bulk melt and enter the galleries between the silicate layers. An essential feature of this process is the flow of macromolecules from a bulk fluid to a confined environment. To model this phenomenon, we have performed molecular-dynamics simulations of the flow of polymer molecules from a bulk melt into a rectangular slit. The simulations are consistent with a diffusive description of the transport, and show qualitative agreement with time-dependent x-ray diffraction measurements of intercalation kinetics in layered nanocomposites.

Exfoliation of a stack of platelets and intercalation of polymer chains: Effects of molecular weight, entanglement, and interaction with the polymer matrix

“…Clay platelets stack together with an interlayer spacing of the order of a nanometer to form a layered structure. Much of the previous studies 10,11,[15][16][17][18] seem to deal with the intercalation of polymer in a slit or 'gallery' formed by two constrained surfaces/platelets with little or no dynamics. Although some of the theoretical investigations 15,16 are too crude to incorporate relevant fluctuations others lack ample mobility of platelets in appropriate host space.…”

“…Investigating the multi-scale characteristics from microscopic details to macroscopic observations of the exfoliation and intercalation of the layers of clay platelets, often difficult in laboratory experiment, is however key to finding ways to control their distribution. Computer simulation experiments [17][18][19][20][21] have become viable learning tools with idealized and relatively simple models in such systems [10][11][12][13][14][15][16][17][18] where it is easier to invoke hypotheses and constraints and vary the range of parameters usually inaccessible in laboratory experiments.…”

Numerical simulation of polymer nanocomposites using self-consistent mean-field model

“…As an alternative, coarse-grained models have been developed. These lump a number of molecules or mers into a single grain and then compute the performance of PNO, [11][12][13][14]18 polymer blends, or block copolymers. 29,30 With growing frequency, MD simulations are being used to solve practical industrial problems.…”

“…In particular, the modulus, hardness, tensile strength, heat deflection temperature, flammability, and barrier properties are likely to be enhanced. 1 The clay dispersion process has been modeled considering the thermodynamics, 2-10 kinetics, [11][12][13][14][15][16][17][18][19][20] and continuum mechanics. 21,22 Unlike conventional composites, polymeric nanocomposites ͑PNC͒ usually contain less than 5 vol % of solid reinforcement.…”

PVA / Montmorillonite Nanocomposites: Development and Properties

“…The obtained nanocomposites exhibited superior mechanical properties without significant reduced in optical transparency. At equilibrium, the nanocomposite structure predicted from thermodynamics corresponds to an intercalated periodic nanocomposite with d-spacing around 1.8 nm, which is expected to be independent of the polymer-to-silicate ratio (Lee et al, 1998). However, thermodynamics can only predict the equilibrium structure.…”