85 research outputs found
Dynamics of curved interfaces
Stochastic growth phenomena on curved interfaces are studied by means of
stochastic partial differential equations. These are derived as counterparts of
linear planar equations on a curved geometry after a reparametrization
invariance principle has been applied. We examine differences and similarities
with the classical planar equations. Some characteristic features are the loss
of correlation through time and a particular behaviour of the average
fluctuations. Dependence on the metric is also explored. The diffusive model
that propagates correlations ballistically in the planar situation is
particularly interesting, as this propagation becomes nonuniversal in the new
regime.Comment: Published versio
Percolation in deposits for competitive models in (1+1)-dimensions
The percolation behaviour during the deposit formation, when the spanning
cluster was formed in the substrate plane, was studied. Two competitive or
mixed models of surface layer formation were considered in (1+1)-dimensional
geometry. These models are based on the combination of ballistic deposition
(BD) and random deposition (RD) models or BD and Family deposition (FD) models.
Numerically we find, that for pure RD, FD or BD models the mean height of the
percolation deposit grows with the substrate length according to
the generalized logarithmic law , where
(RD), (FD) and (BD).
For BD model, the scaling law between deposit density and its mean height
at the point of percolation of type are observed, where is a scaling
coefficient. For competitive models the crossover, %in versus
corresponding to the RD or FD -like behaviour at small and the BD-like
behaviour at large are observed.Comment: 8 pages,4 figures, Latex, uses iopart.cl
Percolation in Models of Thin Film Depositions
We have studied the percolation behaviour of deposits for different
(2+1)-dimensional models of surface layer formation. The mixed model of
deposition was used, where particles were deposited selectively according to
the random (RD) and ballistic (BD) deposition rules. In the mixed one-component
models with deposition of only conducting particles, the mean height of the
percolation layer (measured in monolayers) grows continuously from 0.89832 for
the pure RD model to 2.605 for the pure RD model, but the percolation
transition belong to the same universality class, as in the 2- dimensional
random percolation problem. In two- component models with deposition of
conducting and isolating particles, the percolation layer height approaches
infinity as concentration of the isolating particles becomes higher than some
critical value. The crossover from 2d to 3d percolation was observed with
increase of the percolation layer height.Comment: 4 pages, 5 figure
Effect of Palmitic Acid on the Electrical Conductivity of Carbon Nanotubes−Epoxy Resin Composites
We found that the palmitic acid allows an efficient dispersion of carbon nanotubes in the epoxy matrix. We have set up an experimental protocol in order to enhance the CNTs dispersion in epoxy resin. Electrical conductivity is optimal using a 1:1 CNTs to palmitic acid weight ratio. The associated percolation threshold is found between 0.05 and 0.1 wt % CNTs, i.e., between 0.03 and 0.06 vol %. The SEM image shows essentially individual CNTs which is inagreement with conductivity measurements. In comparison with composites without palmitic acid, the use of palmitic acid improves the electrical properties of CNTs-epoxy resin composites
Decoration of multi-walled carbon nanotubes by polymer wrapping and its application in MWCNT/polyethylene composites
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