The rheology of linear and branched metallocene polyethylenes (m-PEs) was investigated. The linear metallocenes were prepared by gas-phase polymerization, while the branched PEs were commercial resins. Molecular parameters such as Mw, branch type, and molecular weight distribution have influenced the viscoelastic behavior of both linear and branched PEs, whereas branch content (BC) had little i...

Prior mechanical testing of ankle ligaments has focused on quantifying ligament ultimate strength (Attarian et al., 1985; Siegler et al., 1988). Few studies have attempted to model the constitutive behavior of ankle ligaments at sub-failure levels. Although the viscoelastic nature of ankle ligaments has been noted (Attarian et al., 1985), no studies have attempted to create a viscoelastic const...

The standard step-hold load-relaxation profile can yield variable estimates of mechanical properties due to the difficulty in achieving a step strain experimentally. A ramp-hold profile overcomes this limitation if appropriate model functions can be derived. Utilizing Boltzmann hereditary integral operators for two indentation geometries, analytical ramp solutions for load-relaxation were devel...

BACKGROUND The viscoelastic properties of cells have been investigated by a variety of techniques. However, the experimental data reported in literature for viscoelastic moduli differ by up to three orders of magnitude. This has been attributed to differences in techniques and models for cell response as well as to the natural variability of cells. RESULTS In this work we develop and apply a ...

Glass relaxation occurs in a range of temperature during transition from equilibrium to super-cooled liquid. Viscoelastic material model can be applied to simulate glass behavior in the glass transition regime. COMSOL Multiphysics software 4.3b can simulate the stress relaxation with the WLF (WilliamsLandel-Ferry) shift function, but no structural relaxation. In this study we developed a framew...

PURPOSE Fiber-reinforced composite (FRC) posts have gained much interest recently and understanding of their viscoelastic properties is important as they can be used in stress-bearing posterior restorations. The aim of this study was to evaluate the creep behavior and the viscoelastic properties of four commercial FRC posts under different temperatures and different storage conditions. METHOD...

In this paper, we studied the viscoelastic behaviors of isolated aortic elastin using combined modeling and experimental approaches. Biaxial stress relaxation and creep experiments were performed to study the time-dependent behavior of elastin. Experimental results reveal that stress relaxation preconditioning is necessary in order to obtain repeatable stress relaxation responses. Elastin exhib...

Since the physical behavior of many tissues is shown to be viscoelastic, we propose a novel registration technique for medical images via physical principles of viscoelasticity. It allows the template and the target images to differ by large local deformations like viscous fluid and small local deformations like elastic solid. With an extra elastic term introduced, the proposed model constrains...

We study theoretically the viscoelastic properties of sheared binary fluids that have strong dynamical asymmetry between the two components. The dynamical asymmetry arises due to asymmetry between the viscoelastic stresses, particularly the bulk stress. Our calculations are based on the two-fluid model that incorporates the asymmetric stress distribution. We simulate the phase separation proces...

Gastric mucin, a high molecular weight glycoprotein, is responsible for providing the gel-forming properties and protective function of the gastric mucus layer. Bulk rheology measurements in the linear viscoelastic regime show that gastric mucin undergoes a pH-dependent sol-gel transition from a viscoelastic solution at neutral pH to a soft viscoelastic gel in acidic conditions, with the transi...