Model for the Viscosity of Particle Dispersions

Since the past decade, rapid development in nanotechnology has produced several aspects for the scientists and technologists to look into. Nanofluid is one of the incredible outcomes of such advancement. Nanofluids (colloidal suspensions of metallic and nonmetallic nanoparticles in conventional base fluids) are best known for their remarkable change to enhanced heat transfer abilities. Earlier research work has already acutely focused on thermal conductivity of nanofluids. However, viscosity is another important property that needs the same attention due to its very crucial impact on heat transfer. Therefore, viscosity of nanofluids should be thoroughly investigated before use for practical heat transfer applications. In this contribution, a brief review on theoretical models is presented precisely. Furthermore, the effects of nanoparticles' shape and size, temperature, volume concentration, pH, etc. are organized together and reviewed.

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“…In 1999, Bicerano et al [13] suggested a correlation for viscosity of nanofluids. The correlation also shows the volumetric effect of viscosity:…”

Section: Theoretical Studiesmentioning

confidence: 99%

A brief review on viscosity of nanofluids

et al. 2014

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“…Note that for the system viscosity to diverge and not only increase, gelation (i.e., percolation) has to occur; this happens when φ → φ crit (e.g., φ crit = 0.63 for monodisperse hard spheres in random close packing) [81]. To appreciate the link between fractal dimension and gelation, it is sufficient to substitute Eq.…”

Section: Relevance Of the Fractal Concept In Colloid Sciencementioning

confidence: 99%

Fractal-like structures in colloid science

Lazzari

Nicoud

Jaquet

et al. 2016

Advances in Colloid and Interface Science

177

126

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a b s t r a c tThe present work aims at reviewing our current understanding of fractal structures in the frame of colloid aggregation as well as the possibility they offer to produce novel structured materials. In particular, the existing techniques to measure and compute the fractal dimension d f are critically discussed based on the cases of organic/inorganic particles and proteins. Then the aggregation conditions affecting d f are thoroughly analyzed, pointing out the most recent literature findings and the limitations of our current understanding. Finally, the importance of the fractal dimension in applications is discussed along with possible directions for the production of new structured materials.

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“…G' is about the same for the three samples based on 0.05 mg/ml, 0.1 mg/ml, and 0.2 mg/ml in DMF and G' becomes nearly constant at low frequencies. This indicates a transition from a Newtonian liquid to an ideal Hookean solid, which accompanies the formation of a mechanically stable network structure [39] ('jammed network' or 'dispersion gel') [40].…”

Section: Viscoelastic Propertiesmentioning

confidence: 99%

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

Kashiwagi

Fagan

Douglas

et al. 2007

Polymer

Self Cite

169

113

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Particle spatial dispersion is a crucial characteristic of polymer composite materials and this property is recognized as especially important in nanocomposite materials due to the general tendency of nanoparticles to aggregate under processing conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability containing the same amount of SWNTs, the relationships between the quantified dispersion levels and physical properties show about four orders of magnitude variation in storage modulus, almost eight orders of magnitude variation in electric conductivity, and about 70 % reduction in peak mass loss rate at the highest dispersion level used in this study. The observation of such a profound effect of SWNT dispersion indicates the need for objective dispersion metrics for correlating and understanding how the properties of nanocomposites are determined by the concentration, shape and size of the nanotubes. conditions. We introduce dispersion metrics along with a specified dispersion scale over which material homogeneity is measured and consider how the dispersion metrics correlate quantitatively with the variation of basic nanocomposite properties. We then address the general problem of quantifying nanoparticle spatial dispersion in model nanocomposites of single wall carbon nanotubes (SWNT) dispersed in poly(methyl methacrylate) (PMMA) at a fixed SWNT concentration of 0.5 % using a 'coagulation' fabrication method. Two methods are utilized to measure dispersion, UV-Vis spectroscopy and optical confocal microscopy. Quantitative spatial dispersion levels were obtained through image analysis to obtain a 'relative dispersion index ' (RDI) representing the uniformity of the dispersion of SWNTs in the samples and through absorbance. We find that the storage modulus, electrical conductivity, and flammability † This was carried out by the National Institute of Standards and Technology (NIST), an agency of the US Government and is not subject to copyright in the US. ‡ Correspondence to: T. Kashiwagi (E-mail: takashi.kashiwagi@nist.gov) 1 property of the nanocomposites correlates well with the RDI. For the nanocomposites containing the same amount of SWNTs, the relationships betw...

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Model for the Viscosity of Particle Dispersions

Cited by 233 publications

References 190 publications

A brief review on viscosity of nanofluids

A brief review on viscosity of nanofluids

Fractal-like structures in colloid science

Relationship between dispersion metric and properties of PMMA/SWNT nanocomposites

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