Small deformation viscoelastic response of gum and highly filled elastomers

1990 ◽  
Vol 29 (2) ◽  
pp. 152-162 ◽  
Author(s):  
R. G. Stacer ◽  
D. M. Husband
Keyword(s):  
Small Deformation ◽  
Viscoelastic Response ◽  
Filled Elastomers

Viscoelastic Response and Adhesion Properties of Highly Filled Elastomers

1987 ◽  
Vol 60 (2) ◽  
pp. 227-244 ◽  
Author(s):  
R. G. Stacer ◽  
D. M. Husband ◽  
H. L. Stacer
Keyword(s):  
Fracture Energy ◽  
Contact Time ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Small Deformation ◽  
Viscoelastic Response ◽  
Adhesion Properties ◽  
Adhesive Fracture ◽  
Filled Elastomers ◽  
Nonlinear Viscoelastic

Abstract The viscoelastic response of four highly-filled elastomers has been investigated. Small deformation dynamic testing of these materials reveals thay they are nonlinear viscoelastic, as well as thermorheologically complex. Nonlinear viscoelastic behavior was observed as a pronounced strain dependence in the range of 0.1 to 10%. The degree of this nonlinear response was quantified through a constitutive equation containing a single nonlinear factor; resultant nonlinear factors for the various materials were compared and evaluated. Thermorheologically complex behavior was displayed by slightly different shift coefficients to superpose G'′ and G″ data. An approach for calculating material resilience from the viscoelastic data was also developed and a nomographic technique presented for its application. A composite adhesive joint, consisting of two layers of a filled NBR compound bonded together by a filled putty interlayer, was also studied. It was found that both the adhesive fracture energy and the effect of interlayer thickness could be related to the loss modulus of the putty interlayer. Finally, the effect of contact time on bond strength was evaluated and results presented as a master curve of adhesive fracture energy vs. temperature-reduced contact time.

Viscoelastic Properties of Rubberlike Composite Propellants and Filled Elastomers

1962 ◽  
Vol 35 (2) ◽  
pp. 291-310 ◽  
Author(s):  
Robert F. Landel ◽  
Thor L. Smith
Keyword(s):  
Volume Fraction ◽  
Small Deformation ◽  
Universal Function ◽  
Glass Temperature ◽  
Quasi Equilibrium ◽  
Temperature Function ◽  
Hencky Strain ◽  
Filled Elastomers ◽  
Equilibrium Modulus ◽  
Filler Particles

Abstract The mechanical properties of rubberlike composite propellants and similar filled elastomers are determined largely by the volume fraction of filler, the visco-elastic properties of the binder, and the interactions between the binder and filler particles. The ratio of the quasi-equilibrium modulus of the composite to that for the unfilled elastomer increases with the volume fraction of the filler, apparently according to an equation of the form proposed by Eilers and Van Dyck. However, the same ratio for the dynamic storage modulus decreases as the frequency is increased or the temperature is decreased. The time-dependent tensile properties can be characterized by stress-strain curves measured at different strain rates and temperatures. Both the small deformation and ultimate properties can be represented by master curves, which are functions only of the experimental time scale, along with a temperature function which is a near-universal function of the glass temperature. Propellants under constant loads initially exhibit creep which is qualitatively similar to that of unfilled elastomers, but subsequently dewetting of the filler particles may begin and this causes the deformation to increase exponentially with time. A discussion is given of the use of Poisson's ratio, defined in terms of Hencky strain and measured as a function of extension, to indicate the initiation of dewetting and the subsequent volume increase.

Mesoscopic gelation of chitosan and genipin at below critical concentrations

2017 ◽  
Author(s):  
Christoph Engwer ◽  
Ronja Loy ◽  
Ioannis S. Chronakis ◽  
Ana C. Mendes ◽  
Francisco M. Goycoolea
Keyword(s):  
Sol Gel ◽  
Crosslinking Agent ◽  
Small Deformation ◽  
Macroscopic Appearance ◽  
Critical Concentrations ◽  
Gelation Kinetics ◽  
Gardenia Jasminoides ◽  
Sol Gel Transition ◽  
Low Cytotoxicity ◽  
High Concentrations

Genipin is increasingly used as a crosslinking agent for chitosans due to its low cytotoxicity as a naturally occurring extract of the plant <i>Gardenia jasminoides</i>. Genipin reacts with the primary amino groups of chitosan to form blue hydrogels. We studied the gelation kinetics of different chitosans varying in their properties (molar mass 34 000-213 000 g mol<sup>-1</sup>, degree of acetylation 9-20%) and genipin in detail. We found that critical sol-gel transition times obtained from dynamic light scattering were in good agreement with the results obtained by small deformation oscillatory rheometry and microviscosimetry at high concentrations of chitosan. However, at below critical concentrations, we found a second regime of gelation that followed the same Ross-Murphy's gelation kinetics. The macroscopic appearance of these samples was a suspension of weak gel-like particles that were sensitive to mechanical forces. We believe that the material is a mesoscopic gel, as described for other polymers. To the best of our knowledge, this is the first time that this phenomenon has been described for the gelling system of chitosan and genipin.

Experimental Study on Mix Ratio Design and Road Performance of Medium and Small Deformation Seamless Expansion Joints of Bridges

2021 ◽  
pp. 036119812098474
Author(s):  
Pengzhen Lu ◽  
Chenhao Zhou ◽  
Simin Huang ◽  
Yang Shen ◽  
Yilong Pan
Keyword(s):  
Traffic Safety ◽  
Performance Test ◽  
Asphalt Mixture ◽  
Small Deformation ◽  
Expansion Joint ◽  
Expansion Joints ◽  
Mixture Ratio ◽  
The Road ◽  
Marshall Test ◽  
Road Performance

Expansion joints are a weak and fragile part of bridge superstructure. The damage or failure of the expansion joint will lead to the decline of bridge durability and endanger the bridge structure and traffic safety. To improve the service life and performance of bridge expansion joints, the ideal method is to use seamless expansion joints. In this study, starting from the commonly used asphalt mixture gradation of seamless expansion joint, and taking into account the actual situation of bridge expansion joint structure and environment in China, the gradation and asphalt-aggregate ratio are preliminarily designed. Through a Marshall test, the corresponding asphalt mixture is evaluated and analyzed according to the stability, flow value, and void ratio, and the optimal gradation and asphalt-aggregate ratio are determined. Finally, the asphalt mixture is prepared with the mixture ratio design, and the test results of an immersion Marshall test, fatigue performance test, and full-scale test verify that the asphalt mixture meets the road performance requirements of seamless expansion joints. On the basis of the experimental data, the performance of large sample asphalt mixture is continuously tested, compared, and optimized. The results show that the asphalt mixture ratio designed is true and reliable, which can provide reference for the optimal design of seamless expansion joint filler.

scholarly journals Linear and Nonlinear Normal Interface Stiffness in Dry Rough Surface Contact Measured Using Longitudinal Ultrasonic Waves

2021 ◽  
Vol 11 (12) ◽  
pp. 5720
Author(s):  
Saeid Taghizadeh ◽  
Robert Sean Dwyer-Joyce
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Ultrasonic Wave ◽  
Bulk Material ◽  
Nonlinear Differential Equations ◽  
Small Deformation ◽  
Ultrasonic Waves ◽  
Solid Contact ◽  
Interfacial Stiffness ◽  
Linear And Nonlinear

When two rough surfaces are loaded together contact occurs at asperity peaks. An interface of solid contact regions and air gaps is formed that is less stiff than the bulk material. The stiffness of a structure thus depends on the interface conditions; this is particularly critical when high stiffness is required, for example in precision systems such as machine tool spindles. The rough surface interface can be modelled as a distributed spring. For small deformation, the spring can be assumed to be linear; whilst for large deformations the spring gets stiffer as the amount of solid contact increases. One method to measure the spring stiffness, both the linear and nonlinear aspect, is by the reflection of ultrasound. An ultrasonic wave causes a perturbation of the contact and the reflection depends on the stiffness of the interface. In most conventional applications, the ultrasonic wave is low power, deformation is small and entirely elastic, and the linear stiffness is measured. However, if a high-powered ultrasonic wave is used, this changes the geometry of the contact and induces nonlinear response. In previous studies through transmission methods were used to measure the nonlinear interfacial stiffness. This approach is inconvenient for the study of machine elements where only one side of the interface is accessible. In this study a reflection method is undertaken, and the results are compared to existing experimental work with through transmission. The variation of both linear and nonlinear interfacial stiffnesses was measured as the nominal contact pressure was increased. In both cases interfacial stiffness was expressed as nonlinear differential equations and solved to deduce the contact pressure-relative surface approach relationships. The relationships derived from linear and nonlinear measurements were similar, indicating the validity of the presented methods.

scholarly journals Nutritional and Rheological Features of Lentil Protein Isolate for Yoghurt-Like Application

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1692
Author(s):  
Theresa Boeck ◽  
Emanuele Zannini ◽  
Aylin W. Sahin ◽  
Juergen Bez ◽  
Elke K. Arendt
Keyword(s):  
Laser Scanning ◽  
Base Material ◽  
Small Deformation ◽  
Protein Isolate ◽  
Protein Supplementation ◽  
Water Holding Capacity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Deformation Analysis ◽  
Water Holding

The substitution of animal protein with proteins of plant origin is a viable way to decrease the negative impact caused by animal husbandry on the environment. Pulse consumption has been widely promoted as a nutritious contribution to protein supplementation. In this study, an emulsion of lentil (Lens culinaris) protein isolate is fermented with lactic acid bacteria (LAB) to manufacture a yoghurt alternative and the techno-functional properties compared to a dairy- and a soy-based product with similar protein contents. The yoghurt-like products are subjected to large and small deformation analysis, quantification of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP), water holding capacity tests, protein profile analysis and the gel structure is visualised by confocal laser scanning microscopy (CLSM). The lentil yoghurt alternative shows good water holding capacity, high firmness and consistency values in large deformation analysis, with cohesiveness and viscosity not significantly different from that of dairy yoghurt. The high gel strength and rigidity of the lentil yoghurt gels measured by small deformation analysis is well-reflected in the dense protein matrix in the CLSM graphs. FODMAP content of the lentil yoghurt is very low, making it suitable for consumption by irritable bowel syndrome (IBS) patients. Our results show that lentil protein isolate is an excellent base material for producing a plant-based yoghurt alternative.

Sign in / Sign up

Export Citation Format

Share Document