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Viscosity‐concentration relationships for nanodispersions based on glass transition point
Author(s) -
Pal Rajinder
Publication year - 2017
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22810
Subject(s) - volume fraction , viscosity , glass transition , nanoparticle , volume (thermodynamics) , relative viscosity , materials science , thermodynamics , transition point , fraction (chemistry) , chemistry , chemical physics , nanotechnology , chromatography , composite material , polymer , physics
The theoretical background relevant to modelling of the viscous behaviour of nanodispersions (nanosuspensions and nanoemulsions) is discussed. Using free‐volume arguments, a simple model is developed to describe the viscous behaviour of nanodispersions. A large pool (16 sets) of available experimental data on the zero‐shear relative viscosity of nanodispersions is correlated on the basis of the effective volume fraction of solvated nanoparticles/nanodroplets. It is found that the experimental data can be successfully correlated using the volume fraction of solvated nanoparticles/nanodroplets only below the glass transition volume fraction of solvated nanoparticles/nanodroplets. The glass transition volume fraction of solvated nanoparticles/nanodroplets is about 0.58, which is in agreement with the value found in the literature. The experimental relative viscosity data of all sixteen sets of nanoemulsions and nanosuspensions collapse on to a single curve which is well described by the proposed model provided that the volume fraction of solvated nanoparticles/nanodroplets is below the glass transition value of 0.58. Above the glass transition volume fraction of 0.58, the correlation of relative viscosity on the basis of solvated volume fraction is not successful. Above the glass transition point, the nanodispersion is in an arrested (jammed) state and is expected to possess yield‐stress. Thus the concept of zero‐shear viscosity itself becomes unreliable and meaningless above the glass transition point.