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Universal viscosity behavior of polymer nanocomposites.
Jagannathan T Kalathi1, Gary S Grest, Sanat K Kumar
1Department of Chemical Engineering, Columbia University, New York, New York 10027, USA.
Physical Review Letters
|December 11, 2012
Summary
Adding small nanoparticles to polymer melts acts like plasticizers, significantly reducing shear viscosity regardless of polymer chain length. This effect can be tuned by adjusting nanoparticle-polymer interactions.
Area of Science:
- Polymer Science
- Materials Science
- Computational Chemistry
Background:
- Polymer melts are complex fluids with applications in various industries.
- Understanding and controlling their flow behavior (viscosity) is crucial for processing and performance.
- Nanoparticle fillers are often added to polymers to modify properties, but their effect on viscosity is not fully understood.
Purpose of the Study:
- To investigate the effect of small, energetically neutral nanoparticles on the shear viscosity of polymer melts.
- To determine the influence of polymer chain length and nanoparticle size on viscosity reduction.
- To explore the role of polymer-nanoparticle interactions in modulating viscosity.
Main Methods:
- Nonequilibrium molecular dynamics (NEMD) simulations were employed.
- Systematic variation of nanoparticle loading, polymer chain length, and nanoparticle size.
- Analysis of shear viscosity as a function of simulation parameters.
Main Results:
- Small, neutral nanoparticles significantly reduce polymer melt shear viscosity, acting as plasticizers.
- This viscosity reduction is largely independent of polymer chain length.
- The plasticizing effect persists for nanoparticles up to the chain size or entanglement mesh size.
- Strongly attractive polymer-nanoparticle interactions can overcome the viscosity reduction.
Conclusions:
- Small nanoparticles can effectively plasticize polymer melts, lowering shear viscosity.
- This phenomenon offers a route to control the rheological properties of polymer nanocomposites.
- Simulation data provides a basis for predicting the flow behavior of filled polymer systems.
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