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  2. Stress relaxation - Wikipedia

    en.wikipedia.org/wiki/Stress_relaxation

    The amount of relaxation which takes place is a function of time, temperature and stress level, thus the actual effect it has on the system is not precisely known, but can be bounded. Stress relaxation describes how polymers relieve stress under constant strain. Because they are viscoelastic, polymers behave in a nonlinear, non-Hookean fashion. [1]

  3. Viscoelasticity - Wikipedia

    en.wikipedia.org/wiki/Viscoelasticity

    When the back stress is the same magnitude as the applied stress, the material no longer creeps. When the original stress is taken away, the accumulated back stresses will cause the polymer to return to its original form. The material creeps, which gives the prefix visco-, and the material fully recovers, which gives the suffix -elasticity. [2]

  4. Linear low-density polyethylene - Wikipedia

    en.wikipedia.org/wiki/Linear_low-density...

    During a shearing process, such as extrusion, LLDPE remains more viscous and, therefore, harder to process than an LDPE of equivalent melt index. The lower shear sensitivity of LLDPE allows for a faster stress relaxation of the polymer chains during extrusion, and, therefore, the physical properties are susceptible to changes in blow-up ratios.

  5. Viscoplasticity - Wikipedia

    en.wikipedia.org/wiki/Viscoplasticity

    Figure 4. a) Applied strain in a relaxation test and b) induced stress as functions of time over a short period for a viscoplastic material. As shown in Figure 4, the relaxation test [19] is defined as the stress response due to a constant strain for a period of time. In viscoplastic materials, relaxation tests demonstrate the stress relaxation ...

  6. Maxwell material - Wikipedia

    en.wikipedia.org/wiki/Maxwell_material

    Dependence of dimensionless stress upon dimensionless time under constant strain. If a Maxwell material is suddenly deformed and held to a strain of , then the stress decays on a characteristic timescale of , known as the relaxation time.

  7. Time–temperature superposition - Wikipedia

    en.wikipedia.org/wiki/Time–temperature...

    Schematic of the evolution of the instantaneous modulus E(t,T) in a static relaxation test. t is the time and T is the temperature. Consider the relaxation modulus E at two temperatures T and T 0 such that T > T 0. At constant strain, the stress relaxes faster at the higher temperature.

  8. Thermally induced shape-memory effect (polymers) - Wikipedia

    en.wikipedia.org/wiki/Thermally_induced_shape...

    These movements are called relaxation process and the formation of "random strings" to eliminate stresses is called shape-memory loss. A polymer will exhibit the shape-memory effect if it is susceptible to being stabilized in a given state of deformation, preventing the molecules from slipping and regaining their higher entropy (lower energy) form.

  9. Kelvin–Voigt material - Wikipedia

    en.wikipedia.org/wiki/Kelvin–Voigt_material

    Similarly, the total stress will be the sum of the stress in each component: [4] σ Total = σ S + σ D . {\displaystyle \sigma _{\text{Total}}=\sigma _{\rm {S}}+\sigma _{\rm {D}}.} From these equations we get that in a Kelvin–Voigt material, stress σ , strain ε and their rates of change with respect to time t are governed by equations of ...