Steady shear and dynamic strain thickening of halloysite nanotubes and fumed silica shear thickening composite

2018 ◽  
Vol 38 (10) ◽  
pp. 915-923
Author(s):  
Pavni Passey ◽  
Mansi Singh ◽  
Sanjeev K. Verma ◽  
Debarati Bhattacharya ◽  
Rajeev Mehta
Keyword(s):  
Shear Rate ◽  
Fumed Silica ◽  
Shear Thickening ◽  
Halloysite Nanotubes ◽  
Spherical Particles ◽  
Dynamic Strain ◽  
Critical Shear Rate ◽  
Shear Thickening Fluids ◽  
Protective Fabrics ◽  
Critical Viscosity

Abstract Developing the shear thickening fluids (STF) which can be used for soft body armours requires an in depth study of various parameters related to its constituents so that a high critical viscosity along with high critical shear rate can be obtained. Shape of the constituting particles is one such important parameter. Elongated and nanosize particles provide high critical viscosity to the fluid, whereas spherical particles show high critical shear rates. STF were prepared using halloysite (Hal) nanotubes of different concentrations with fumed silica (spheres) and their rheological properties were studied. A better non-flocculated structure was obtained at 1% Hal in 20% fumed silica composition, exhibiting a critical viscosity of 25 Pas at a critical shear rate 160 s−1 as compared to that of only spherical particle STF (10 Pas and 200 s−1). The oscillatory tests revealed that this composition, with a better consistent reproducible behaviour and better stability than the STF without Hal, would be suitable as a high impact resistant material. Gel formation does not take place, rather the fluid behaves like a dispersed sol, making it a better choice for using with protective fabrics. The rheology was studied at different temperatures ranging from 0°C to 55°C.

scholarly journals Continuous phenomenological modeling for the viscosity of shear thickening fluids

2018 ◽  
Vol 8 ◽  
pp. 184798041878655 ◽  
Author(s):  
Minghai Wei ◽  
Li Sun ◽  
Peipei Qi ◽  
Chunguang Chang ◽  
Chunyang Zhu
Keyword(s):  
Shear Rate ◽  
Shear Thickening ◽  
Data Sets ◽  
External Energy ◽  
Critical Shear Rate ◽  
Phenomenological Modeling ◽  
Shear Thickening Fluid ◽  
Shear Thickening Fluids ◽  
Viscosity Modeling ◽  
Independent Experimental Data

In general, shear thickening fluids show a marked increase in viscosity beyond a critical shear rate, which can be attributed to the hydrodynamic clustering effects, where in any external energy acting on a shear thickening fluid is dissipated quickly. However, there is a lack of theoretical modeling to predict the viscosity curve of shear thickening fluids, which changes continuously with the increasing shear rate. In this article, a phenomenological continuous viscosity modeling for a class of shear thickening fluids is proposed. The modeling predicts shear thickening and thinning behaviors that are naturally exhibited by shear thickening fluids for high and high enough values of the shear rate. The result shows that the phenomenological modeling provides a very good fit for several independent experimental data sets. Therefore, the proposed modeling can be used in numerical simulations and theoretical analysis across different engineering fields.

Characterization and Application of Shear Thickening Fluids

2013 ◽  
Vol 405-408 ◽  
pp. 2503-2506
Author(s):  
Zi Guo Wang ◽  
Zhi Wu Yu ◽  
Yu Yan Sun ◽  
Qing Yuan Li
Keyword(s):  
Shear Rate ◽  
Impact Loading ◽  
Protective Clothing ◽  
Shear Thickening ◽  
Van Der Waals Forces ◽  
Cementitious Materials ◽  
Critical Shear Rate ◽  
Interparticle Forces ◽  
Shear Thickening Fluids ◽  
Liquid To Solid Transition

The shear thickening phenomenon was explained in this paper. The characteristics of shear thickening fluids (STFs), including reversibility and liquid to solid transition at critical shear rate were presented. Also, the applications of STFs for protective clothing and equipment were discussed. Since little references can be found which concern the effect of interparticle forces like Van der Waals forces on the performance of cementitious materials subjected to impact loading, understanding the mechanism of STF and knowing how its structure affects the properties, behaviors, and resulting applications is expected to inspire potential designs for building cementitious materials.

scholarly journals Rheology of Fumed Silica and Polyethylene Glycol Shear Thickening Suspension with Nanoclay as an Additive

2019 ◽  
Vol 69 (4) ◽  
pp. 402-408 ◽  
Author(s):  
Mansi Singh ◽  
Sanjeev K Verma ◽  
Ipsita Biswas ◽  
Rajeev Mehta
Keyword(s):  
Steady State ◽  
Polyethylene Glycol ◽  
Fumed Silica ◽  
Shear Thickening ◽  
Dynamic State ◽  
Shear Thickening Fluid ◽  
Organically Modified ◽  
The Difference ◽  
Critical Viscosity ◽  
Stability And Consistency

Shear thickening properties of fumed silica-polyethylene glycol (PEG) with shear thickening fluid (STF) of different concentrations and with an organically modified clay, Nanomer I.28 E as nano-additive have been investigated by both steady-state and dynamic state rheology. Difference in rheology if instead of nanoclay, an equal wt% of additional fumed silica is added to 20 per cent fumed silica-PEG200 STF, has been studied. At 25 °C, in case of addition of nanoclay the increase in critical viscosity is less than that observed for same additional amount of fumed silica. Interestingly, an opposite result is seen at higher temperatures i.e. 45 °C and 55 °C. Moreover, the difference in steady-state and dynamic state viscosity values decreases on addition of nanoclay. It is noted that an increase in concentration of clay increases the value of dynamic parameters whereas for STF of only fumed silica particles the values are constant irrespective of the change in concentration. More importantly, ease of processing, elasticity, stability and consistency of rheological results of STF increases to a significant extent on addition of relatively inexpensive nano-additive.

scholarly journals The Chain Distribution Tensor: Linking Nonlinear Rheology and Chain Anisotropy in Transient Polymers

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 848 ◽  
Author(s):  
Shankar Lalitha Sridhar ◽  
Franck Vernerey
Keyword(s):  
Shear Rate ◽  
Polymer Networks ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Underlying Mechanism ◽  
Weissenberg Number ◽  
Critical Shear Rate ◽  
Nonlinear Rheology ◽  
Non Gaussian ◽  
Chain Force

Transient polymer networks are ubiquitous in natural and engineered materials and contain cross-links that can reversibly break and re-form. The dynamic nature of these bonds allows for interesting mechanical behavior, some of which include nonlinear rheological phenomena such as shear thickening and shear thinning. Specifically, physically cross-linked networks with reversible bonds are typically observed to have viscosities that depend nonlinearly on shear rate and can be characterized by three flow regimes. In slow shear, they behave like Newtonian fluids with a constant viscosity. With further increase in shear rate, the viscosity increases nonlinearly to subsequently reach a maximum value at the critical shear rate. At this point, network fracture occurs followed by a reduction in viscosity (shear-thinning) with a further increase in shear rate. The underlying mechanism of shear thickening in this process is still unclear with debates between a conversion of intra-chain to inter-chain cross-linking and nonlinear chain stretch under high tension. In this paper, we provide a new framework to describe the nonlinear rheology of transient polymer networks with the so-called chain distribution tensor using recent advances from the transient network theory. This tensor contains quantitatively and statistical information of the chain alignment and possible anisotropy that affect network behavior and mechanics. We investigate shear thickening as a primary result of non-Gaussian chain behavior and derive a relationship for the nonlinear viscosity in terms of the non-dimensional Weissenberg number. We further address the criterion for network fracture at the critical shear rate by introducing a critical chain force when bond dissociation is suddenly accelerated. Finally, we discuss the role of cross-linker density on viscosity using a “sticky” reptation mechanism in the context of previous studies on metallo-supramolecular networks with reversible cross-linkers.

Tuning the Rheology of Nano-Sized Silica Suspensions with Silicon Nitride Particles

2019 ◽  
Vol 56 ◽  
pp. 63-70 ◽  
Author(s):  
Selim Gürgen
Keyword(s):  
Silicon Nitride ◽  
Shear Rate ◽  
Shear Thickening ◽  
Critical Shear Rate ◽  
Rheological Measurements ◽  
Additive Particles ◽  
Thickening Behavior ◽  
Silica Suspensions ◽  
Nanosized Silica

In this paper, a non-Newtonian fluid was fabricated dispersing nanosized silica particles in a polyethylene glycol medium. The rheology of the suspension was investigated in a stress-controlled rheometer under increasing shear rate. Based on the rheological measurements, the suspension exhibited shear thickening behavior which gives a drastic viscosity grow with the increase in the shear rate. In order to investigate the role of the micro-sized additive particles on the rheology of silica based suspension, silicon nitride particles were included in the suspension with three different concentrations. The results were discussed in terms of important parameters for the shear thickening mechanism such as critical shear rate, peak viscosity, thickening ratio and initial viscosity. According to the results, shear thickening behavior can be controlled altering the amount of silicon nitride particles in the suspension.

scholarly journals Investigation of penetration into woven fabric specimens impregnated with shear thickening fluid

2018 ◽  
Vol 25 (1) ◽  
pp. 205-212 ◽  
Author(s):  
Naser Kordani ◽  
Ali Sadough Vanini
Keyword(s):  
Molecular Weight ◽  
Hydrogen Bond ◽  
Shear Rate ◽  
High Molecular Weight ◽  
Particle Surface ◽  
Shear Thickening ◽  
Silica Particles ◽  
Woven Fabric ◽  
Critical Shear Rate ◽  
Shear Thickening Fluid

AbstractIn this paper, the effect of weight fraction of nano silica (hydrophilic fumed silica particles) and molecular mass of polyethylene glycol (PEG) on the rheological properties such as the critical shear rate of fluids has been studied. Dynamic moduli based on strain and the effects of increasing the molecular weight are presented. Constructed samples with high-molecular-weight PEG have higher initial, final and critical viscosities. Also, higher molecular chains in the polymer and preventing the movement of most of these chains against the relative motion of liquid (viscosity) will cause higher viscosity in samples. Critical shear rate is lower in the provided samples with high-molecular-weight PEG. Polymer branches in these suspensions are absorbed by the surface of the particles. Due to OH bonds in the silica particles and also due to the presence of this bond in PEG, creating a hydrogen bond is likely. Such a hydrogen bond between the polymer yarn and the particle surface causes surface absorption of the particles. To show the effect of molecular weight on fibers, woven fabric specimens impregnated with shear thickening fluid (STF) have been examined by penetration and pressure test diagrams have been investigated. In a sample with higher molecular weight, displacement to yield point is higher and residence to penetration does not show much difference.

scholarly journals New analysis and correlation between steady and oscillatory tests in fumed silica-based shear thickening fluids

2019 ◽  
Vol 58 (10) ◽  
pp. 647-655 ◽  
Author(s):  
Andres G. Moron ◽  
Maria Jesus L. Boada ◽  
Beatriz L. Boada ◽  
Vicente Diaz
Keyword(s):  
Fumed Silica ◽  
Shear Thickening ◽  
Shear Thickening Fluids

scholarly journals Comparison of rheological behaviors with fumed silica-based shear thickening fluids

2016 ◽  
Vol 28 (3) ◽  
pp. 197-205 ◽  
Author(s):  
Alain D. Moriana ◽  
Tongfei Tian ◽  
Vitor Sencadas ◽  
Weihua Li
Keyword(s):  
Fumed Silica ◽  
Shear Thickening ◽  
Rheological Behaviors ◽  
Shear Thickening Fluids
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