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Investigators from Swiss Federal Institute of Technology Zero in on Nanoparticles (Continuum Model for the Phase Behavior, Microstructure, and...

August 15, 2014



Investigators from Swiss Federal Institute of Technology Zero in on Nanoparticles (Continuum Model for the Phase Behavior, Microstructure, and Rheology of Unentangled Polymer Nanocomposite Melts)

By a News Reporter-Staff News Editor at Science Letter -- Current study results on Nanoparticles have been published. According to news originating from Zurich, Switzerland, by NewsRx correspondents, research stated, "We introduce a continuum model for polymer melts filled with nanoparticles capable of describing in a unified and self-consistent way their microstructure, phase behavior, and rheology in both the linear and nonlinear regimes. It is based on the Hamiltonian formulation of transport phenomena for fluids with a complex microstructure with the final dynamic equations derived by means of a generalized (Poisson plus dissipative) bracket."

Our news journalists obtained a quote from the research from the Swiss Federal Institute of Technology, "The model describes the polymer nanocomposite melt at a mesoscopic level by using three fields (state variables): a vectorial (the momentum density) and two tensorial ones (the conformation tensor for polymer chains and the orientation tensor for nanoparticles). The dynamic equations are developed for nanoparticles with an arbitrary shape but then they are specified to the case of spherical ones. Restrictions on the parameters of the model are provided by analyzing its thermodynamic admissibility. A key ingredient of the model is the expression for the Helmholtz free energy A of the polymer nanocomposite. At equilibrium this reduces to the form introduced by Mackay et al. (Science 2006, 311, 1740-1743) to explain the phase behavior of polystyrene melts filled with silica nanopartides. Beyond equilibrium, A contains additional terms that account for the coupling between microstructure and flow. In the absence of chain elasticity, the proposed evolution equations capture known models for the hydrodynamics of a Newtonian suspension of particles."

According to the news editors, the research concluded: "A thorough comparison against several sets of experimental and simulation data demonstrates the unique capability of the model to accurately describe chain conformation and swelling in polymer melt nanocomposites and to reliably fit measured rheological data for their shear and complex viscosity over large ranges of volume fractions and deformation rates."

For more information on this research see: Continuum Model for the Phase Behavior, Microstructure, and Rheology of Unentangled Polymer Nanocomposite Melts. Macromolecules, 2014;47(13):4493-4513. Macromolecules can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Macromolecules - www.pubs.acs.org/journal/mamobx)

The news correspondents report that additional information may be obtained from P.S. Stephanou, ETH, Dept. of Mat, CH-8093 Zurich, Switzerland. Additional authors for this research include V.G. Mavrantzas and G.C. Georgiou (see also Nanoparticles).

Keywords for this news article include: Zurich, Europe, Switzerland, Nanotechnology, Emerging Technologies

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Science Letter


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