Dispersion Of Nanoparticles In Nanocomposites Research Articles

Multifractal Analysis of Particle Dispersion and Interphase Percolation in Nanocomposites

The dispersion of nanoparticles in nanocomposites of an epoxy matrix reinforced with alumina (10nm) and zinc oxide (100nm) is analyzed using FIB/FESEM images, varying the volumetric fraction of fillers from 0.2 % to 6.0 %. The nanofillers dispersion images were transformed to binary files and the multifractal spectrum was calculated. From these data the relation between agglomerate and individual particle dimensionalities related to the interphase percolation was investigated. Interphase percolation of nanocomposites should be achieved when the dimensionality of agglomerations is greater than the dimensionality of individual particles. The actual percolation state of the interphase is determined, matching the experimental nanocomposites behavior for electrical behavior at AC and dielectric breakdown at DC.

The influences of the transfer method and particle surface chemistry on the dispersion of nanoparticles in nanocomposites

The synthesis via in situ polymerization and characterization of nanocomposites (NCs) made from silica (SiO(2)) nanoparticles in a methyl methacrylate (MMA) monomer matrix is reported. We first investigate the transfer of well-defined spherical silica nanoparticles (NPs) (average radius R = 24.2 ± 3.2 nm) into the monomer solvent. We study the influence of two transfer methods and different surface chemistries on the resulting colloidal stability. The first transfer method consists of drying the silica particles into powder before dispersing them via ultrasonication in the MMA matrix. The second is based on repetitive centrifugations to exchange NPs from their synthetic milieu to pure MMA, avoiding the dried powder state. These transfer methods are compared for two kinds of NP surface chemistry, natural silanol (Si-OH) groups of the silica NPs and an additional silane coupling agent, namely 3-(trimethoxysilyl)propyl methacrylate (TPM), which mimics the monomeric group of the MMA dispersing milieu. We then characterize the morphology of the resulting nanocomposites prepared via in situ polymerization at a fixed amount of dispersed NPs (2.2 wt%; 1 vol%) using a combination of transmission electron microscopy (TEM) from ultramicrotomed nanocomposite films, thermogravimetry (TGA) and small angle X-ray scattering (SAXS).

Static, rheological and mechanical properties of polymer nanocomposites studied by computer modeling and simulation

Polymer nanocomposites (PNCs) often exhibit excellent mechanical, thermal, electrical and optical properties, because they combine the performances of both polymers and inorganic or organic nanoparticles. Recently, computer modeling and simulation are playing an important role in exploring the reinforcement mechanism of the PNCs and even the design of functional PNCs. This report provides an overview of the progress made in past decades in the investigation of the static, rheological and mechanical properties of polymer nanocomposites studied by computer modeling and simulation. Emphases are placed on exploring the mechanisms at the molecular level for the dispersion of nanoparticles in nanocomposites, the effects of nanoparticles on chain conformation and glass transition temperature (T(g)), as well as viscoelastic and mechanical properties. Finally, some future challenges and opportunities in computer modeling and simulation of PNCs are addressed.