Shear Thickening Behaviour of Composite Propellant Suspension under Oscillatory Shear

2016 ◽  
Vol 66 (3) ◽  
pp. 222 ◽  
Author(s):  
D. Singh ◽  
G. Dombe ◽  
C. Bhongale ◽  
P. P. Singh ◽  
Mehilal Maurya ◽  
...  
Keyword(s):  
Strain Amplitude ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Rheological Behaviour ◽  
Complex Viscosity ◽  
Solid Particles ◽  
Dynamic Moduli ◽  
Composite Propellant ◽  
Plateau Region ◽  
Temperature Constant

Composite propellant suspensions consist of highly filled polymeric system wherein solid particles of different sizes and shapes are dispersed in a polymeric matrix. The rheological behaviour of a propellant suspension is characterised by viscoplasticity and shear rate and time dependant viscosity. The behaviour of composite propellant suspension has been studied under amplitude sweep test where tests were performed by continuously varying strain amplitude (strain in %, γ) by keeping the frequency and temperature constant and results are plotted in terms of log γ (strain amplitude) vs logGʹ and logGʺ (Storage modulus and loss modulus, respectively). It is clear from amplitude sweep test that dynamic moduli and complex viscosity show marked increase at critical strain amplitude after a plateau region, infering a shear thickening behaviour.

Composition – Property Relations in Shear Thickening Fluids

2014 ◽  
Vol 87 ◽  
pp. 91-97
Author(s):  
Łukasz Wierzbicki ◽  
Marcin Leonowicz
Keyword(s):  
High Strain ◽  
Volume Fraction ◽  
Solid Phase ◽  
Loss Modulus ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
High Viscosity ◽  
Polypropylene Glycol ◽  
Shear Thickening Fluids ◽  
Composition Property

It was shown that fumed silica particles (FS), dispersed in polypropylene glycol (PPG), form shear thickening fluids (STF). PPGs with different molar mass were tested. The best combination of the properties (high viscosity, obtained at high shear rate) present the fluids composed of 7 nm FS and PPG 425. The highest volume fraction of FS, which was possible to disperse in PPG 425, was 25%. This fluid exhibited the highest viscosity. The highest magnitude of shear thickening effect was obtained, however, for 17.5 vol.% of the solid phase. Dynamic oscillatory shear experiments were conducted at either a constant amplitude or frequency. The constant strain amplitude tests showed, that for the frequency sweep, the systems showed viscous properties, except that of 25 vol.% of FS in PPG 425, which exhibited elastic properties in almost entire range of the frequency investigated. For the constant strain sweep, for low strains, the elastic modulus and loss modulus were hardly dependent on the strain, but for relatively high strain, this dependency was increasing. Also the complex viscosity was also growing for high strain values.

Study of the rheological properties of polypropylene/talc/nanoclay ternary hybrid nano composites

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Alavi ◽  
M. Esfandeh ◽  
J. Morshedian ◽  
Y. Jahani
Keyword(s):  
Loss Modulus ◽  
Rheological Behaviour ◽  
Complex Viscosity ◽  
Xrd Analysis ◽  
Ternary Blend ◽  
Hydrodynamic Effect ◽  
Low Frequencies ◽  
Melt Compounding ◽  
Twin Screw ◽  
Simultaneous Use

AbstractModification of polypropylene (PP) properties by the addition of particulate fillers has been of interest for several years. In the recent years, the simultaneous use of nanofillers and conventional reinforcing fillers and study of the effect of these hybrid systems on various properties of composite has gained the attention of many researchers. In this paper, nanocomposites based on PP/Talc/Nanoclay were prepared at various filler levels via melt compounding of the ingredients in a twin-screw extruder. Here, a polypropylene grafted maleic anhydride (PP-g-MA)/Nanoclay master batch was prepared at 140 oC. The masterbatch was then used to prepare ternary compounds through a simultaneous feeding system, in a ZSK extruder at 210 °C. The extrudate was granulated and then re-extruded through a slit die, to prepare the test specimens. SEM and XRD analysis were used to characterise the systems. Rheological behaviour of the specimens was studied using a parallel plate rheometer. In the ternary blend on comparing with the neat PP, the complex viscosity (η*) is increased with increasing overall filler content; however, at low frequencies this increase is governed by the content of nano filler while at high frequencies it is mainly determined by talc content. A similar trend was also observed for the variations of storage modulus (G′) and loss modulus (G″) with frequency. The results showed that the simultaneous use of nano and micro size fillers considerably affects the melt elasticity. It is believed that the hybrid system increases the hydrodynamic effect of filler particles in the molecular motion of the polymer.

scholarly journals Investigação do comportamento viscoelástico de amostras de licor negro oriundas do processo de polpação Kraft da Cenibra-MG à 25 oc

2021 ◽  
Vol 3 (4) ◽  
pp. 2411-2425
Author(s):  
Ângelo M. L. Denadai ◽  
Euler T. Dos Santos ◽  
Humberto L. Dos Santos ◽  
José M. Q. Moreira ◽  
Fernando C. De Oliveira ◽  
...  
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Shear Thickening ◽  
Complex Viscosity ◽  
Kraft Pulping ◽  
Chemical Recovery ◽  
Molecular Fragmentation ◽  
Black Liquors

RESUMO O comportamento viscoelástico dos licores negros de eucalipto (LN) do processo de polpação Kraft da CENIBRA foi avaliado a 25 oC, na ausência (LNSC) e na presença (LNCC) de cinzas da ebulição da recuperação química, que são geralmente misturadas com licores negros para melhorar a eficiência da recuperação química. As amostras foram tosquiadas em campos rotativos e oscilatórios, mostrando os comportamentos de cisalhamento e cisalhamento dependentes da taxa de cisalhamento aplicada. A viscosidade complexa - *, o módulo de armazenamento e perda - G' e G'', e a tensão de rendimento 0 para LNSC foram todos muito superiores ao LNCC, provavelmente devido à fragmentação molecular causada pela adição de cinzas.   ABSTRACT The viscoelastic behavior of eucalyptus black liquors (LN) from CENIBRA Kraft pulping process was evaluated at 25 oC, in absence (LNSC) and in presence (LNCC) of ash from chemical recovery boiling, which are usually mixed with black liquors to improve the efficiency of chemical recovery. The samples were sheared upon rotational and oscillatory fields, showing booth shear-thickening and shear-thinning behaviors dependent of applied shear rate. The complex viscosity – h*, storage and loss modulus – G’ and G’’, and yield stress s0 for LNSC were all very higher than LNCC, probably due the molecular fragmentation caused by addition of ashes.

Influence of κ-Carrageenan, Modified Starch and Inulin Addition on Rheological and Sensory Properties of Non-fat and Non-added Sugar Dairy Dessert

2020 ◽  
Vol 16 (4) ◽  
pp. 462-469
Author(s):  
Zhaleh Sheidaei ◽  
Bahareh Sarmadi ◽  
Seyede M. Hosseini ◽  
Fardin Javanmardi ◽  
Kianoush Khosravi-Darani ◽  
...  
Keyword(s):  
Storage Modulus ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Textural Properties ◽  
Complex Viscosity ◽  
Sensory Properties ◽  
Modified Starch ◽  
Consumer Health ◽  
Added Sugar ◽  
Textural Parameters

<P>Background: The high amounts of fat, sugar and calorie existing in dairy desserts can lead to increase the risk of health problems. Therefore, the development of functional and dietary forms of these products can help the consumer health. </P><P> Objective: This study aims to investigate the effects of &#954;-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. </P><P> Methods: In order to determine the viscoelastic behavior of samples, oscillatory test was carried out and the values of storage modulus (G′), loss modulus (G″), loss angle tangent (tan &#948;) and complex viscosity (&#951;*) were measured. TPA test was used for analysis of the desserts’ texture and textural parameters of samples containing different concentrations of carrageenan, starch and inulin were calculated. </P><P> Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of &#954;-carrageenan and modified starch caused an increase in G′ and G″ as well as &#951;* and a decrease in tan &#948;. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% &#954;-carrageenan, 2.5% starch and 5.5% inulin (sucralose as constant = 0.25%) and this sample was the best treatment with desirable attributes for the production of non-fat and non-added sugar dairy dessert. </P><P> Conclusion: It can be concluded that the concentration of &#954;-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.</P>

Electrical conductivity and rheological properties of carbon black based conductive polymer composites prior to and after annealing

2021 ◽  
pp. 096739112110012
Author(s):  
Qingsen Gao ◽  
Jingguang Liu ◽  
Xianhu Liu
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Percolation Threshold ◽  
Rheological Properties ◽  
Network Formation ◽  
Loss Modulus ◽  
Conductive Polymer ◽  
Complex Viscosity ◽  
Electrical Percolation ◽  
Electrical Percolation Threshold

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.

scholarly journals A Characterization Study of Morphology and Properties of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/Aloe Vera Fibers Biocomposites: Effect of Fiber Surface Treatments

Proceedings ◽  
2020 ◽  
Vol 69 (1) ◽  
pp. 38
Author(s):  
Celia Idres ◽  
Mustapha Kaci ◽  
Nadjet Dehouche ◽  
Idris Zembouai ◽  
Stéphane Bruzaud
Keyword(s):  
Thermal Stability ◽  
Surface Morphology ◽  
Water Absorption ◽  
Loss Modulus ◽  
Aloe Vera ◽  
Fiber Surface ◽  
Complex Viscosity ◽  
Absorption Capacity ◽  
Characterization Study ◽  
Efficient Route

This paper aims to investigate the effect of different chemical modifications of biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and aloe vera bio-fibers incorporated at 20 wt%. The fiber surface was modified with alkaline, organosilanes, and combined alkaline/organosilanes. Surface morphology, thermal stability, water absorption capacity, and rheological behavior of the modified biocomposite materials were studied, and the results compared to both unmodified biocomposites and neat PHBH. The study showed that the modified biocomposites with both alkaline and organosilanes exhibited an improved surface morphology, resulting in a good fiber/matrix interfacial adhesion. As a result, increases in complex viscosity, storage modulus, and loss modulus were observed, whereas water absorption was reduced. Thermal stability remained almost unchanged, with the exception of the biocomposite treated with alkaline, where this property decreased significantly. Finally, the coupling of alkaline and organosilane modification is an efficient route to enhance the properties of PHBH biocomposites.

scholarly journals Effect of nano-solid particles on the mechanical properties of shear thickening fluid (STF) and STF-Kevlar composite fabric

2021 ◽  
Vol 16 ◽  
pp. 155892502110448
Author(s):  
Mingmei Zhao ◽  
Jinqiu Zhang ◽  
Zhizhao Peng ◽  
Jian Zhang
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Tensile Force ◽  
Shear Thickening ◽  
Solid Particles ◽  
Time Range ◽  
Shear Thickening Fluid ◽  
Pull Out ◽  
Diamond Particles

To analyze the effect of nano-solid particles on the mechanical properties of shear thickening fluid (STF) and its Kevlar composite fabric. In this study, nano-silica and polyethylene glycol (PEG 200) were used as dispersed and continuous phases. Nano-graphite and nano-diamond particles were used as additives to prepare STF and Kevlar composite fabric. Study the friction characteristics and rheological characteristics of STF at different temperatures. Explore the STF’s mechanical response under transient high-speed impact conditions through the split Hopkinson pressure bar experiment. The mechanical properties of STF-Kevlar fabric are studied through yarn pull-out test and burst experiments. The experimental results show that the intermolecular repulsive force of STF is enhanced under a high-temperature environment, and shear thickening effect is reduced. Nano-diamond particles strengthen the contact coupling force and contact probability between the particle clusters, so that the maximum viscosity of the system reaches 1679 Pa s, the thickening ratio reaches 318 times, and the rheological properties of the shear thickening fluid are improved. The results of the SHPB experiment show that the STF can complete a dynamic response within a 50–75 µs time range, and the maximum stress can reach 78 MPa. The bullet’s incident kinetic energy is not only transformed into thermal energy and phase change energy of solid-liquid conversion, but also into frictional energy between particles. The mechanical experiments of STF-Kevlar composite fabrics show that the tensile force value of STF5-Kevlar is the largest (10.3 N/13.5 N), and the tensile force of neat Kevlar was the smallest (4.3 N/4.9 N). The maximum bearing capacity (0.3 kN) and absorption energy (51.8 J) of Neat Kevlar are less than those of STF1-Kevlar (3.2 kN, 116.7 J) and STF3-Kevlar (1.9 kN, 88.2 J), and STF5-Kevlar (4.7 kN, 143.3 J). Fabric’s failure mode is converted from partial yarn extraction to overall deformation and rupture of the fabric. Therefore, by changing the solid additives’ parameters, the STF and the composite fabric’s mechanical properties can be effectively controlled, which provides a reference for preparing the STF and fabric composite materials.

Nanofiller-Polymer Interactions At and Above the Glass Transition Temperature

2000 ◽  
Vol 661 ◽  
Author(s):  
Ai-jun Zhu ◽  
Sanford S. Sternstein
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strain Amplitude ◽  
Filler Content ◽  
Loss Modulus ◽  
Surface Treatments ◽  
Filler Concentration ◽  
Large Strains ◽  
Chain Entanglement

ABSTRACTRheological data are reported for a series of fumed silica filled PVAc samples, using fillers of different specific surface areas and surface treatments. Data at the glass transition temperature and 45 C above Tg are presented. The addition of filler systematically increases Tg, and all samples obey time-temperature superposition. However, temperature normalized and frequency normalized plots of loss modulus indicate that there is no change in the dispersion of the glass transition, with the only exception being a surface modified with covalently bonded polymer chains. Thus, contrary to expectations, an increase in filler content or change in surface treatment has no effect on the relative shape of the relaxation time spectrum at the glass transition. At 45 C above Tg, different behavior is observed. The filler concentration has a major effect on the nonlinearity of dynamic moduli vs. strain amplitude, with higher filler content reducing the strain amplitude at which nonlinear behavior is observed. Specific filler surface treatments result in major changes in the shape of the loss factor versus strain amplitude relationship. These results suggest that interfacial interactions strongly modify the far-field polymer behavior with respect to chain entanglement slippage at large strains.

Rheology of colloids

Surfactants ◽  
2019 ◽  
pp. 400-424
Author(s):  
Bob Aveyard
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Shear Thickening ◽  
Rheological Behaviour ◽  
Maxwell Model ◽  
Colloidal Dispersions ◽  
Shear Strain Rate ◽  
Plastic Behaviour ◽  
Shear Thickening Fluids ◽  
External Forces

Lyophobic colloidal dispersions, aggregated surfactant systems, and polymer solutions, as well as foams and emulsions, can all be deformed by weak external forces; rheology is the study of deformation and flow of materials. Various rheological quantities arising from the response of a material to shear are defined. For liquids the stress, τ‎, applied is related to the rate of deformation, that is, the shear strain rate, γ̇. For Newtonian fluids τ‎ and γ̇ are linearly related and τ‎ / γ̇ is the viscosity, η‎. Other nonlinear relationships correspond to shear thinning and shear thickening fluids and to plastic behaviour in which there is a yield stress. Viscoelastic systems exhibit both viscous and elastic properties; such behaviour is often treated using the simple Maxwell model. Some illustrative experimentally observed rheological behaviour is presented.

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