Rheology of surface-modified titania nanoparticles dispersed in PDMS melts: The significance of the power law
Schematic illustration of the relationship between total interaction potential and dispersion structure. Figure used with permission from Lewis, Journal of American Ceramic Society 83(10), 2341–2359, 2000. Copyright 2000, The American Ceramic Society.
Transmission electron micrograph of commercial titania nanoparticles used in experiment.
Anomalous measurement: The sinusoidal curve usually corresponds to the visual appearance of large clusters on edge interface. Data at 0.04/s are considered invalid whereas variation in the data at 0.4/s (○) falls within experimental error [Ndong and Russel (2011)].
Relative viscosity versus shear stress for octadecyl-treated TiO2 nanoparticles in (a) neat and (b) binary 4k/77 k PDMS melts (15% loading).
Relative viscosity versus shear rate x melt viscosity for octadecyl-treated TiO2 nanoparticles (15% loading) showing collapse of the data onto a single curve. The dotted line is the fit to Eq. (3).
Relative viscosity versus shear stress for bare titania nanoparticle (15% loading) in (a) neat and (b) binary PDMS melts. The dashed lines are the correlation fits to the data, whereas the dotted line represents the C18 data set.
Relative viscosity versus shear rate for 9 k-grafted titania nanoparticles (15% loading) in (a) neat and (b) binary PDMS melts. The dashed lines are the correlation fits to the data.
(a) The power law index n (empty) and τ/μ (solid) dependence on melt M w . (b) the apparent (empty), hydrodynamic (solid) thicknesses estimated from C18 calibration and from scaling (grey). The symbols are: circles for bare, squares for grafted and triangles for C18.
Weight average molecular weight (M w ), polydispersity index (PDI), number of statistical segments (N or P) and viscosity (μ). Polymer characteristics: m o = 37 g/mol and l = 0.84 nm [Russel et al. (1989)], C ∞ = 5.2 [Brandrup and Immergut (1999)].
Correlation parameter for C18 TiO2 in neat and binary PDMS melts.
Correlation parameter for bare TiO2 in neat and binary PDMS melts. NV denotes the fit to the correlation is too poor because of the low n.
Correlation parameter for 9 k-grafted TiO2 in neat and binary PDMS melts.
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