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Modeling interfacial effects on transport properties: mechanical properties of polymers,
thermal properties of nanofluids

Abstract : Physical phenomena at interfaces are responsible for many properties of great practical interest in
composite materials. Using molecular dynamics simulations, we modeled and studied the microscale physics
involved in mechanical properties of polymers and in thermal transfer in nanofluids.

Developing a method for local study of dynamics in a polymer melt, we have explained the mecha-
nisms involved in the mechanical response of a pure melt to an external solicitation. In the case of a wall
polymer interface, we have shown that the presence of grafted chains slows down dynamics and increases
entanglement density locally in a slice roughly a typical chain size wide. For a bare flat surface dynamics are
accelerated and there are less entanglements near the wall. The study of an entangled polymer melt with
sub-chain size fillers showed that filler-polymer attraction leads to an effective increase in entanglement den-
sity via fillers acting as reticulations. These phenomena can explain the measured moderate reinforcement in
filled melts at high temperature in absence of glassy effects.

By studying interfacial effects on thermal transport in a nanofluid we developed a sensible method for
measuring particle-fluid thermal resistance. We showed that conductivity is well predicted by effective me-
dium calculation. The influence of Brownian motion was shown to be negligible and the experimentally
measured enhanced conductivity of nanofluids is attributed to collective effects such as particle aggregation.
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Contributor : Mihail Vladkov <>
Submitted on : Tuesday, October 2, 2007 - 5:43:08 PM
Last modification on : Monday, October 19, 2020 - 10:54:14 AM
Long-term archiving on: : Monday, September 24, 2012 - 1:01:27 PM

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  • HAL Id : tel-00176186, version 1

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Mihail Vladkov. Modeling interfacial effects on transport properties: mechanical properties of polymers,
thermal properties of nanofluids. Data Analysis, Statistics and Probability [physics.data-an]. Université Claude Bernard - Lyon I, 2007. English. ⟨tel-00176186⟩

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