Rheological studies of uncured epoxy–organoclay nanocomposite coatings

AbstractWe investigated the influence of loading two different types of organoclay on the linear viscoelastic properties of an uncured epoxy nanocomposite coating. Meanwhile, the effect of sonication in the dispersion process on the characteristics of nanocomposite has been studied. To achieve fully dispersed structures of clay-epoxy, we applied high shear mixing and high-intensity ultrasound during the synthesis of clay-epoxy nanocomposites.The flow properties of the compositions with clay loadings more than 4 wt% of low CEC quaternary ammonium modified clay, as analyzed by rheomechanical spectroscopy (RMS), showed a solid-like behavior. While the neat resin system exhibited Newtonian flow, some nanodispersed coatings exhibited pseudo plastic flow behavior, typical of polymeric fluids such as gels and pastes. With varying the type of the clay the resultant coatings exhibited a storage modulus ranging from 0.01 to over 400 Pa and a loss modulus ranging from 4 to over 200 Pa. Moreover, the complex viscosity was ranging from 12 to 1100 Pas as the clay loading increased from 0 to 8wt %. The strong increase in modulus of one type of the clays was due to the mainly intercalated and dispersed silicate platelets. The increase rate in storage modulus of these compositions decreased at higher organoclay loadings and was not linear. These results can lead to the prediction of film formation properties and application conditions of these nanocomposite coatings

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

Current Nutrition & Food Science ◽

10.2174/1573401315666190301152645 ◽

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

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. Objective: This study aims to investigate the effects of κ-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. 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 δ) and complex viscosity (η*) 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. Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of κ-carrageenan and modified starch caused an increase in G′ and G″ as well as η* and a decrease in tan δ. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% κ-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. Conclusion: It can be concluded that the concentration of κ-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.

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Viscoelastic Properties of Thixotropic Semisolid Alloy Relating the Microstructure

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.285.380 ◽

2019 ◽

Vol 285 ◽

pp. 380-384

Author(s):

Gerardo Sanjuan-Sanjuan ◽

Ángel Enrique Chavez-Castellanos

Keyword(s):

Storage Modulus ◽

Viscoelastic Properties ◽

Loss Modulus ◽

Viscoelastic Behavior ◽

Complex Viscosity ◽

Plateau Modulus ◽

Complex Shear ◽

Different Temperatures ◽

Semisolid Alloy ◽

The Subject

The subject of this work is to investigate viscoelastic properties such as loss modulus (G ́ ́), storage modulus (G ́), complex shear modulus (G*), complex viscosity (η*) and loss angle () at different temperatures by means of a small-amplitude oscillatory test. These properties allow to provide information about materials structure. For this purpose, we employed a tin-lead alloy (Sn-15%Pb) which exhibits a similar microstructure to aluminum alloys and is the classic alloy for semisolid thixotropic studies. It is interesting to note that the Sn-15%Pb alloy exhibits a slightly decrease in storage modulus (G ́) over the entire frequency (0.01-10Hz) at high temperatures, showing its viscoelastic behavior. In addition, a detailed analysis of master curves (oscillatory tests) was made to relate the semisolid microstructure (solid fraction) with the plateau modulus (GN0) which is directly related with both molecular weight or percolation threshold in polymer and gels science respectively.

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Dynamic Rheological Properties of Concentrated Chitosan Soltions

Applied Rheology ◽

10.1515/arh-2004-0009 ◽

2004 ◽

Vol 14 (3) ◽

pp. 140-147 ◽

Cited By ~ 10

Author(s):

A. Martínez-Ruvalcaba ◽

E. Chornet ◽

D. Rodrigue

Keyword(s):

Storage Modulus ◽

Loss Modulus ◽

Complex Viscosity ◽

Maxwell Model ◽

Viscous Effects ◽

Experimental Conditions ◽

Low Frequencies ◽

Wide Range ◽

Generalized Maxwell Model ◽

Different Temperatures

AbstractA detailed analysis of the dynamic flow properties of chitosan in solution at different temperatures (25 - 45°C), chitosan concentration (0.5% - 2.0%), solvent type (acetic, lactic, and hydrochloric acid), and ionic strength (0 and 0.2M NaCl) has been undertaken. The storage modulus, G’, loss modulus, G’’ and complex viscosity, η* have been determined over a wide range of frequencies and the results are presented using master curves. For the conditions studied, at low frequencies chitosan solutions show a constant complex viscosity which decreases as frequency increases. Likewise, storage modulus, G’ and loss modulus, G’’ increase as frequency increases with G’’ being always greater than G’ (η’ > η’’) indicating that viscous effects are more important than elastic effects. For modelling the oscillatory-shear results we used the generalized Maxwell model. Two empirical equations were used to correlate the data: Cox-Merz rule for viscosity and Laun's rule for primary normal stress difference. Both relations were found to represent our data for the experimental conditions studied.

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Rheological Properties of HDPE based Thermoplastic Polymeric Nanocomposite Reinforced with Multidimensional Carbon-based Nanofillers

Biointerface Research in Applied Chemistry ◽

10.33263/briac124.57095715 ◽

2021 ◽

Vol 12 (4) ◽

pp. 5709-5715

Keyword(s):

Rheological Properties ◽

Storage Modulus ◽

Loss Modulus ◽

Complex Viscosity ◽

Damping Factor ◽

Equal Weight ◽

Functional Elements ◽

Weight Percentage ◽

Potential Applications ◽

Rheological Test

The present investigation focused on the evaluation of rheological properties HDPE reinforced with equal weight percentage (i.e., 0.1 wt. %) of Nano-diamond (0D), Carbon nanotubes (1D), and Graphite Nano-platelets (2D) multidimensional nanofillers. The results like storage modulus, loss modulus, Tan delta, and complex viscosity results expounded from the rheological test with a frequency sweep from 10-1 to 102 rad/s. The highest storage modulus was perceived by 0.1 CNT-based composites, i.e., 18408 Pa, which decreased to 19, 52, and 85 % for 0.1 GNP, 0.1 ND, and pure, respectively. A similar trend was observed for loss modulus and damping factor results. The shear-thinning behavior observed in viscosity results and the addition of ND nanofillers improve the viscosity to a large amount. The potential applications of the composites include polymer gears, landing mats, cams, and various functional elements.

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The Role Of Vorticity In The Formation Of Tribomaterial During Sliding

MRS Proceedings ◽

10.1557/proc-821-p9.6 ◽

2004 ◽

Vol 821 ◽

Cited By ~ 9

Author(s):

Karthikeyan Subramanian ◽

Jian-Hui Wu ◽

David A. Rigney

Keyword(s):

Amorphous Materials ◽

Flow Behavior ◽

Md Simulations ◽

Nanocomposite Coatings ◽

Mechanical Mixing ◽

New Information ◽

Wide Range ◽

Shear Mixing ◽

Embedded Particles ◽

Frictional Energy Dissipation

AbstractThe formation of tribomaterial during sliding is well documented for a wide range of materials. Transfer, adhesion, mechanical mixing and formation of nanocrystals are commonly reported, but the mechanisms involved have not been well understood. Recently, molecular dynamics (MD) simulations have been performed to obtain new information on the response of materials to sliding interactions. The results help to explain experimental observations on simple metals such as copper, bulk metallic glasses and multi-component nanocomposite coatings. When the sliding speed is sufficiently high, the strain rate allows vorticity to develop. It is suggested that the resulting eddies are largely responsible for frictional energy dissipation and mechanical mixing in both crystalline and amorphous materials and for the shear mixing of soft embedded particles in nanocomposite coatings. Similarities of flow behavior with that of fluids are noted.

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Mechanical Properties and Rheological Behavior of Injection Moulded Foaming Bamboo Powder–Polypropylene Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.1980 ◽

2011 ◽

Vol 287-290 ◽

pp. 1980-1986 ◽

Cited By ~ 1

Author(s):

Xia Xing Zhou ◽

Qiao Jia Lin ◽

Li Hui Chen

Keyword(s):

Water Absorption ◽

Rheological Behavior ◽

Loss Modulus ◽

Flow Behavior ◽

Complex Viscosity ◽

Pseudoplastic Fluid ◽

Moulding Process ◽

Polypropylene Composites ◽

Injection Moulding Process ◽

Bamboo Powder

Foamed composites of polypropylene containing bamboo powder were prepared using an injection moulding process. Measurement of density, flexural, tensile and notched impact properties of the prepared composites was carried out. Water absorption of the composites was investigated. The rheological behavior of composites was also investigated by rotary rheometer. The density of microfoamed composites was reduced by about 14%.When the bamboo powder was 50 phr (33.3% by weight), the integrated property was best ; the density was 0.886 g·cm-3 and the flexural, tensile and notched impact strength were 58.72 MPa, 30.86 MPa and 5.246 KJ·m-2 respectively; and the thickness swelling and water absorption were 1.31% and 0.7% after duration of 240 h. The results pointed out the composites showed a flow behavior of pseudoplastic fluid; the storage modulus and loss modulus increased and loss tangent decreased with the increase of bamboo powder content. The composite had a typical shear thinning characteristic and the complex viscosity increased with the content of bamboo powder increased.

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Dynamic Viscoelasticity of Poly(ether Ester) Containing Zinc

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.197-198.1263 ◽

2011 ◽

Vol 197-198 ◽

pp. 1263-1266

Author(s):

Jing Guo ◽

Cheng Nv Hu ◽

Wen Fei Huang

Keyword(s):

Real Number ◽

Complex Modulus ◽

Raw Materials ◽

Loss Modulus ◽

Flow Behavior ◽

Complex Viscosity ◽

Tetrabutyl Titanate ◽

Pseudoplastic Fluid ◽

The Real ◽

Ether Ester

Hexanedioic acid, PEG6000 and zinc oxide (ZnO) was chosen as raw materials,and tetrabutyl titanate as catalyst to synthesize the poly(ether ester) containing zinc (PEEM). PEEM and Diphenyl-methane-diisocyanate (MDI) as chain extender was added into polycaprolactam whose molecular weight is about 4000 for synthesizing poly (ether ester amide) containing zinc (PEEAM). The rheological behavior of PEEAM was investigated by an advanced rheometric expansion system (ARES). Dynamic rheometer was used to measure the structures and properties of PEEAM. The dynamic rheological test indicated that the complex modulus (G*), the dynamic storage modulus (G”) and loss modulus (G’) of the PEEAM increase with the frequency (ω) increasing; the complex viscosity (η*) decreases linearly with the ω increasing, and decreases slightly with the temperature increasing, which indicates obvious flow behavior of pseudoplastic fluid. The Cole-Cole curves are convex, in the low frequency zone, the real number viscosity at 260°C is smaller than the real number viscosity at 230°C. The loss tangent (tan δ) presents a miximum with the increase of ω.

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

Polymers and Polymer Composites ◽

10.1177/09673911211001277 ◽

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.

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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 ◽

10.3390/cgpm2020-07183 ◽

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.

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Rheological and Textural Properties of Apple Pectin-Based Composite Formula with Xanthan Gum Modification for Preparation of Thickened Matrices with Dysphagia-Friendly Potential

Polymers ◽

10.3390/polym13060873 ◽

2021 ◽

Vol 13 (6) ◽

pp. 873

Author(s):

Huaiwen Yang ◽

Chai-Chun Tsai ◽

Jung-Shiun Jiang ◽

Chi-Chung Hua

Keyword(s):

Storage Modulus ◽

Water Consumption ◽

Xanthan Gum ◽

Loss Modulus ◽

Textural Properties ◽

Apple Pectin ◽

Composite Matrix ◽

Low Concentrations ◽

Composite Formula

Modifying the consistency of a given edible fluid matrix by incorporating food thickeners is a common nursing remedy for individuals with dysphagia when adequate water consumption is a concern. As apple pectin (AP) offers nutraceutical benefits, properly formulated apple pectin (AP)-based thickeners featuring xanthan gum (XG) can be superior candidates for preparation of dysphagia-friendly matrices (DFMs). Our recruited DFMs exhibit fluid-like behavior (loss modulus > storage modulus, G” > G’) at lower AP concentrations (2 and 5%, w/w); they turn into weak/critical gels (G’ ≈ G”) as the concentration becomes higher (9%). In contrast, XG-DFMs display gel-like attributes with G’ > G”, even at rather low concentrations (<1%) and become more resistant to sugar, Na+, and Ca2+ modifications. The composite matrix of AP1.8XG0.2 (constraint at 2%) exhibits a confined viscosity of 278 ± 11.7 mPa∙s, which is considered a DFM, in comparison to only AP- or XG-thickened ones. The hardness measurements of XG0.6 and AP1.2XG0.8 are 288.33 ± 7.506 and 302.00 ± 9.849 N/m2, respectively, which potentially represent a promising formulation base for future applications with DFMs; these textural values are not significantly different from a commercially available product (p > 0.05) for dysphagia nursing administrations.

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