Shear modulus measurement

Chemical hardness is an energy parameter that measures the stabilities of molecules—atoms (Pearson, 1997).This is fine for measuring molecular stability, but energy alone is inadequate for solids because they have two types of stability size and shape. The elastic bulk modulus measures the size stability, while the elastic shear modulus measures the shape stability. The less symmetric solids require the full set of elastic tensor coefficients to describe their stabilities. Therefore, solid structures of high symmetry require at least two parameters to describe their stability. 

Tan landa, a damping term, is a measure of the ratio of energy dissipated as heat to the maximum energy stored in the material during one cycle of oscillation. For small to medium amounts of damping. G is the same as the shear modulus measured by other methods at comparable time scales. The loss modulus G" is directly proportional to the heat H dissipated per... 

A variety of rheological tests can be used to evaluate the nature and properties of different network structures in foods. The strength of bonds in a fat crystal network can be evaluated by stress relaxation and by the decrease in elastic recovery in creep tests as a function of loading time (deMan et al. 1985). Van Kleef et al. (1978) have reported on the determination of the number of crosslinks in a protein gel from its mechanical and swelling properties. Oakenfull (1984) used shear modulus measurements to estimate the size and thermodynamic stability of junction zones in noncovalently cross-linked gels. 

Fig. 18. Temperature dependencies of the real ((. ) and imaginary (( .") component of the shear modulus measured at the deformation frequency of lOrad/s for the pure and tapered triblock copolymers pMMA-b-pBA-b-pMMA and p(MMA-grad-BA)-b-pBA-b- p(MMA-grad-BA) of approximately the same overall composition, MW and polydispersity DSC traces are shown to help localize the glass transition temperatures (T ) of the microphases. Reprinted with permission from [94]. Copyright (2000) John Wiley Sons, Inc.

Secant shear modulus measured at 0.5% shear strain. 

Figure 1.12. The logarithm of the shear modulus (measured at 10 sec) vs. temperature. Effects of increased molecular weight and crosslinking are also illustrated.

Figure 9.15. X -(GVGIP)32o frequency dependence of loss shear modulus, G" (0.02 to 200 Hz), and of loss permittivity (20 Hz to 10 Hz) as a function of temperature. When the frequency of the loss maximum is sufficiently low, for example, near 1 kHz, loss shear modulus and loss permittivity can both be determined and have been demonstrated to superimpose for the case of the loss maximum for poly(propylene diol). In the case of X -(GVGIP)32o, the maximum occurs at a frequency that is too high to be reached by shear modulus measurements. Nonetheless, the two measurements are... 

Giri Venkiteela, Sun Zhihui, Najm Husam. 2013. Prediction of Early Age Normal Concrete Compressive Strength Based on Dynamic Shear Modulus Measurements. Journal of Materials in Civil Engineering, 25(1) 3(C38. 

The investigations of model compositions, based on linear elastomers and various fillers, have shown that the yield stress also may be characterized by the value of the complex shear modulus measured at various frequencies. The dependence of the dynamic modulus on the filler concentration characterizes critical concentrations of the filler, above which the viscoelastic behavior of composition drastically changes. Dynamic modulus corresponding to the yield stress does not depend on the matrix viscosity or its nature. This fact indicates a predominant role of the structural frame for rheological properties of filled polymers. 

Elastic (shear) modulus measurements were carried out on cylindrical gel samples using a TA.XT2I HR Texture Analyser (Stable Micro Systems, UK). Swollen networks were uniaxially compressed (at constant volume) between two parallel flat plates. The stress-strain isotherms were determined in the range of deformation ratio 0.7 < < 1. 

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