Dynamic Rheological Behaviors of the Bone Scaffold Reinforced by Chitin Fibres

2005 ◽  
Vol 475-479 ◽  
pp. 2387-2390 ◽  
Author(s):  
X.M. Li ◽  
Qing Ling Feng
Keyword(s):  
Viscoelastic Properties ◽  
Loss Factor ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Materials Processing ◽  
Bone Scaffold ◽  
Rheological Behaviors ◽  
Wide Range ◽  
Yielding Behavior

In this study, a novel bioabsorbable porous bone scaffold reinforced by chitin fibres was prepared, the porosity of which is about 90 % and the pore size is approximately 200µm. The Advanced Rheological Enlarged System (ARES) was used to study the dynamic rheological behaviors of the ropy materials which would be made into the reinforced scaffold. The increase of the fibres’ volume content (Cf) enhanced the complex modulus (G*) and complex viscosity (h*) of the materials, the reason of which is that the fibres formed networks in the materials. When Cf increased from 35 % to 45 %, the storage modulus (G’) and loss modulus (G’’) curve showed obvious yielding behavior, which indicates that G’ and G’’ of the materials are hardly variable in a wide range. When Cf was more than 35 %, the loss factor (tand) was obviously lower than 1 and the materials exhibited viscoelastic properties, which result in a disadvantage for materials’ processing.

Characterization of viscoelastic properties of minced beef meat thawed by ohmic and conventional methods

2019 ◽  
Vol 26 (4) ◽  
pp. 277-290 ◽  
Author(s):  
Mutlu Cevik ◽  
Filiz Icier
Keyword(s):  
Ambient Temperature ◽  
Viscoelastic Properties ◽  
Cold Water ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Creep Recovery ◽  
Recoverable Compliance ◽  
Meat Samples ◽  
Minced Meat

Frozen minced meat samples having fat contents of 2%, 10% and 18% were thawed using different methods (refrigeration thawing at ambient temperature of +4 ℃, under running cold water (+4 ℃) thawing, ohmic thawing for 10, 13 and 16 V/cm). Viscoelastic properties were determined by using rheological tests (oscillation and creep/recovery tests). Storage modulus, loss modulus, complex modulus, loss tangent, dynamic viscosity and complex viscosity values of minced meat samples increased as fat content increased. As frequency value increased, the modulus values of meat samples increased but dynamic and complex viscosity values of the samples decreased. The minced meat samples thawed by different methods had recoverable compliance values. The compliance values of meat samples during creep region can be well characterized by Burgers model. Ohmic thawing can be used as an alternative thawing method since it resulted in similar rheological properties of minced meat samples compared to refrigeration thawing at ambient temperature of +4 ℃ and under running cold water (+4℃) thawing.

Viscoelastic Properties of Thixotropic Semisolid Alloy Relating the Microstructure

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.

Effects of concentration and temperature on the rheological behavior of concentrated sodium lignosulfonate (NaLS) solutions

Holzforschung ◽  
2015 ◽  
Vol 69 (3) ◽  
pp. 265-271 ◽  
Author(s):  
Qianqian Tang ◽  
Mingsong Zhou ◽  
Dongjie Yang ◽  
Xueqing Qiu
Keyword(s):  
Viscoelastic Properties ◽  
Loss Modulus ◽  
Relaxation Times ◽  
Viscoelastic Behavior ◽  
Complex Viscosity ◽  
Industrial Applications ◽  
Sodium Lignosulfonate ◽  
All Solutions ◽  
Effects Of Temperature ◽  
Rheological Experiments

Abstract Concentrated sodium lignosulfonate (NaLS) solutions have wide industrial applications. Therefore, the viscoelastic properties of NaLS in concentrations of 55%–63% have been investigated between 5°C and 55°C by means of a dynamic rheological technique, namely, the oscillatory rheological experiments were conducted in a rheometer in the small amplitude oscillatory mode. All solutions showed “shear-thinning” behavior over frequency. The complex viscosity (η*) increased and the loss tangent (tanδ) decreased with increasing concentrations. Both the storage modulus (G′) and the loss modulus (G″) increased with increasing frequencies and concentrations. The change in viscoelastic behavior was probably caused by stronger aggregation effects. However, the effects of temperature on the viscoelastic properties are more complex. For 60% NaLS, G′, G″, and η* decreased, but tanδ increased with increasing temperatures. When the temperature exceeded 20°C, G′, G″, and η* increased, but tanδ decreased, and the relaxation times were increased as a function of temperature. The change in viscoelasticity as a function of temperature may also be related to intermolecular aggregation and the swelling of aggregates. The conductivity experiments indicated that the formation of a greater strength of network structures at higher levels of concentrations between 55% and 63% and temperatures between 20°C and 55°C was probably responsible for elasticity enhancement.

Dynamic Rheological Properties of Concentrated Chitosan Soltions

2004 ◽  
Vol 14 (3) ◽  
pp. 140-147 ◽  
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.

Analysis of Effects of High Temperature on Asphalt Binder

2013 ◽  
Vol 325-326 ◽  
pp. 97-101
Author(s):  
Phu Cuong Cao ◽  
Zhong Yin Guo ◽  
Yong Shun Yang ◽  
Zhi Chao Xue
Keyword(s):  
High Temperature ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Asphalt Binder ◽  
Great Influence ◽  
Complex Viscosity ◽  
Modified Asphalt ◽  
Resistance Parameter ◽  
Variation Of Parameters ◽  
Sbs Modified Asphalt

The study of effects of high temperature on asphalt binder based on viscoelasticity theory will help clarify the influence mechanism of temperature on asphalt binder. Based on the theory of viscoelasticity, the Dynamic Shear Rheology test is used as study method. The objective of this study is to analyze and determine the features of asphalt binder under the effect of high temperature. Meanwhile, study subjects are AH70 asphalt, SBS modified asphalt and MAC modified asphalt. The result indicates that temperature increases have great influence on asphalt binder, which are shown by the variation of parameters quickly decrease. The relationship between temperature and such parameters as complex modulus, storage modulus, loss modulus, complex viscosity, storage viscosity, loss viscosity, rutting resistance parameter and fatigue resistance parameter can be described as regression of power function.

scholarly journals Empirical Models for the Viscoelastic Complex Modulus with an Application to Rubber Friction

2021 ◽  
Vol 11 (11) ◽  
pp. 4831
Author(s):  
Marco Furlan Tassara ◽  
Kyriakos Grigoriadis ◽  
Georgios Mavros
Keyword(s):  
Dynamic Testing ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Friction Model ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Robust Fitting ◽  
Rubber Friction ◽  
Wide Range ◽  
Bell Functions

Up-to-date predictive rubber friction models require viscoelastic modulus information; thus, the accurate representation of storage and loss modulus components is fundamental. This study presents two separate empirical formulations for the complex moduli of viscoelastic materials such as rubber. The majority of complex modulus models found in the literature are based on tabulated dynamic testing data. A wide range of experimentally obtained rubber moduli are used in this study, such as SBR (styrene-butadiene rubber), reinforced SBR with filler particles and typical passenger car tyre rubber. The proposed formulations offer significantly faster computation times compared to tabulated/interpolated data and an accurate reconstruction of the viscoelastic frequency response. They also link the model coefficients with critical sections of the data, such as the gradient of the slope in the storage modulus, or the peak values in loss tangent and loss modulus. One of the models is based on piecewise polynomial fitting and offers versatility by increasing the number of polynomial functions used to achieve better fitting, but with additional pre-processing time. The other model uses a pair of logistic-bell functions and provides a robust fitting capability and the fastest identification, as it requires a reduced number of parameters. Both models offer good correlations with measured data, and their computational efficiency was demonstrated via implementation in Persson’s friction model.

Optimization of Damping Properties of Staggered Composites Through Microstructure Design

2018 ◽  
Vol 85 (10) ◽  
Author(s):  
Junjie Liu ◽  
Xusheng Hai ◽  
Wenqing Zhu ◽  
Xiaoding Wei
Keyword(s):  
Loss Factor ◽  
Loss Modulus ◽  
Low Frequency ◽  
Underlying Mechanism ◽  
Damping Properties ◽  
Microstructure Design ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Wide Range ◽  
The Matrix

Many natural materials, such as shell and bone, exhibit extraordinary damping properties under dynamic outside excitations. To explore the underlying mechanism of these excellent performances, we carry out the shear-lag analysis on the unit cell in staggered composites. Accordingly, the viscoelastic properties of the composites, including the loss modulus, storage modulus, and loss factor, are derived. The damping properties (particularly, the loss modulus and loss factor) show an optimization with respect to the constituents' properties and morphology. The optimal scheme demands a proper selection of four key factors: the modulus ratio, the characteristic frequency of matrix, aspect ratios of tablets, and matrix. The optimal loss modulus is pointed out to saturate to an upper bound that is proportional to the elastic modulus of tablets when the viscosity of matrix increases. Furthermore, a loss factor even greater than one is achievable through microstructure design. Without the assumption of a uniform shear stress distribution in the matrix, the analysis and formulae reported herein are applicable for a wide range of reinforcement aspect ratios. Further, for low-frequency loading, we give practical formulae of the three indexes of damping properties. The model is verified by finite element analysis (FEA) and gives novel ideas for manufacturing high damping composites.

Dynamic viscoelastic properties of Chinese fir (Cunninghamia lanceolata) during moisture desorption processes

Holzforschung ◽  
2016 ◽  
Vol 70 (6) ◽  
pp. 547-555 ◽  
Author(s):  
Tianyi Zhan ◽  
Jiali Jiang ◽  
Hui Peng ◽  
Jianxiong Lu
Keyword(s):  
Cell Wall ◽  
Viscoelastic Properties ◽  
Loss Factor ◽  
Loss Modulus ◽  
Polymer Networks ◽  
Chinese Fir ◽  
Cunninghamia Lanceolata ◽  
Unstable State ◽  
Factor Ratios ◽  
Moisture Desorption

Abstract The viscoelasticity of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) during moisture desorption processes were examined at 30°C and two relative humidity (RH) modes: RHramp-down mode from 85 to 0% RH, and RHisohume mode at 0, 30, and 60% RH, respectively. Dynamic viscoelastic properties were determined in a multi-frequency range of 1, 2, 5, 10, and 20 Hz. In both RH modes, desorption of water resulted in increasing stiffness and decreasing damping. The reduction in moisture content caused an unstable state in the cell wall due to the formation of free volumes in cell wall and rearrangement of hydrogen bonds within the polymer networks. Higher ramping rates resulted in greater destabilization, and the unstable state was more pronounced at a lower frequency. The ratio of storage modulus at 1 and 20 Hz remained unchanged during both RH modes. The ratios of loss modulus and loss factor at 1 and 20 Hz increased during the RHramp-down and decreased during the RHisohume period. The changes of loss modulus or loss factor ratios at two frequencies were suitable for evaluation of the unstable state. The instability was aggravated with reducing RH and slightly recovered at constant RH.

Prediction of Dynamic Modulus of Asphalt Mixture Based on Viscoelastic Properties of Asphalt Mortar

2013 ◽  
Vol 651 ◽  
pp. 419-423
Author(s):  
Xiao Li Zhan
Keyword(s):  
Dynamic Modulus ◽  
Viscoelastic Properties ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Asphalt Mixture ◽  
Experimental Measurements ◽  
Dynamic Shear ◽  
Different Temperatures ◽  
Viscoelastic Characteristics ◽  
Asphalt Mortar

The objective of this study is to predict the asphalt mixture dynamic modulus using the viscoelastic properties of asphalt mortar. The dynamic viscoelastic characteristics of asphalt mortar and asphalt mixture are tested at different temperatures and loading frequencies using dynamic shear rheometer, such as storage modulus, loss modulus and phase angle. The complex modulus of asphalt mortar, volume parameters and Hirsch model were used to predict complex modulus of asphalt mixture. The experimental measurements of dynamic modulus were employed to compare with the predictions. The result showed this method can predict complex modulus of asphalt mixture very well.

Rheological Behaviors of Carbonaceous Materials Suspended in Sodium Alginate Solutions

2014 ◽  
Vol 906 ◽  
pp. 232-237 ◽  
Author(s):  
Hai Xiang Liu ◽  
Ye Qiang Tan ◽  
Qing Xu Zhang ◽  
Xue Qin ◽  
Ran Ran Zheng ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Loss Modulus ◽  
Chemical Properties ◽  
Complex Viscosity ◽  
Carbonaceous Materials ◽  
Rheological Measurement ◽  
Rheological Behaviors ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
And Chemical Properties

Three kinds of carbonaceous materials with different structural and chemical properties, Carbon Black (CB), Multi-walled Carbon Nanotubes (MWNTs), and Graphene Oxide (GO), were well suspended in sodium alginate (SA) solutions, and the suspension rheological behaviors were investigated in details. Steady rheological results showed that the suspensions exhibited same shear-thinning behaviors as SA solution. Dynamic rheological results showed that the complex viscosity (η*) was similar to that of steady rheological measurement, and both SA solution and SA/carbonaceous materials suspensions exhibited liquid-like behaviors, confirmed by the loss modulus larger than the storage modulus. The loss factor tanδremarkably decreased for SA/GO solution compared with SA/CB and SA/MWNTs suspension at the same concentration, indicating the increase of elasticity via interactions between the GO and SA.

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