Viscoelastic nonlinear

Schuler, K.W., Nunziato, J.W., and Walsh, E.K., Recent Results in Nonlinear Viscoelastic Wave Propagation, Internat. J. Solids and Structures 9, 1237-1281... 

P. E. Rouse. The theory of nonlinear viscoelastic properties of dilute solutions of scaling polymers. J Chem Phys 27 1273-1280, 1953. 

A. Khatory, F. Lequeux, F. Kern, S. J. Candau. Linear and nonlinear viscoelasticity of semidilute solutions of wormlike micelles at high-salt content. Langmuir 9 1456-1464, 1993. 

Sui, C., McKenna, G.B., and Puskas, J.E. Nonlinear viscoelastic response of dendritic (arborescent) polyisobutylenes in single- and reversing double-step shearing flows, J. Rheol, 51, 1143, 2007. 

In particular it can be shown that the dynamic flocculation model of stress softening and hysteresis fulfils a plausibility criterion, important, e.g., for finite element (FE) apphcations. Accordingly, any deformation mode can be predicted based solely on uniaxial stress-strain measurements, which can be carried out relatively easily. From the simulations of stress-strain cycles at medium and large strain it can be concluded that the model of cluster breakdown and reaggregation for prestrained samples represents a fundamental micromechanical basis for the description of nonlinear viscoelasticity of filler-reinforced rubbers. Thereby, the mechanisms of energy storage and dissipation are traced back to the elastic response of tender but fragile filler clusters [24]. 

Strain Sweep Test Protocols for Nonlinear Viscoelasticity Investigations.826... 

Nonlinear Viscoelasticity along Rubber Processing Lines.830... 

Stream Effects and Nonlinear Viscoelasticity in Rubber Processing Operations... 

With respect to stream rheological effects in rubber processing, and despite all the restrictions discussed above, it seems nevertheless that the key information is how the nonlinear viscoelasticity is related to the processing behavior of mbber compounds. Such information can be deduced from the appropriate test procedure with the RPA, providing one considers the capabilities of the instmment to provide nonlinear viscoelastic data. 

FT rheometry is a powerful technique to document the nonlinear viscoelastic behavior of pure polymers as observed when performing large amplitude oscillatory strain (LAOS) experiments. When implemented on appropriate instmments, this test technique can readUy be applied on complex polymer systems, for instance, filled mbber compounds, in order to yield significant and reliable information. Any simple polymer can exhibit nonlinear viscoelastic properties when submitted to sufficiently large strain in such a case the observed behavior is so-called extrinsic... 

Strain Sweep Test Protocols eor Nonlinear Viscoelasticity Investigations... 

Odd torque harmonics become significant as strain increases and are therefore considered as the nonlinear viscoelastic signature of tested materials, only available through FT rheometry. Figure 30.10 shows the typical pattern of corrected relative TTHC (i.e., T(nw/lw)) versus strain y that, in most cases, can be modeled with a simple equation, i.e.. 

NONLINEAR VISCOELASTICITY ALONG RUBBER PROCESSING LINES... 

Figure 30.14 shows an interesting aspect of RPA-FT experiments, i.e., the capability to quantify the strain sensitivity of materials through parameter B of ht Equation 30.3. As can be seen, curatives addition strongly modifies this aspect of nonlinear viscoelastic behavior, with furthermore a substantial change in strain history effect. Before curatives addition, mn 2 data show very lower-strain... 

FIGURE 30.21 Mixing silica-filled compound overall cfianges in nonlinear viscoelastic character along the mixing fine. 

FIGURE 30.22 Mixing silica-filled compound Complex modulus versus strain amplitude as modeled with Equation 30.3 typical changes in nonlinear viscoelastic features along the mixing hne. 

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