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viscoelasticity

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Published: 01 November 2012
Fig. 17 Schematic representation of viscoelastic behavior of a polymer. Loading produces an immediate elastic strain followed by viscous flow. Unloading produces an immediate elastic recovery followed by additional recovery over a period of time. Source: Ref 14 More
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Published: 01 August 2005
Fig. 7.6 Schematic representation of viscoelastic behavior of a polymer. Loading produces an immediate elastic strain followed by viscous flow. Unloading produces an immediate elastic recovery followed by additional recovery over a period of time. More
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Published: 01 December 2004
Fig. 1 Visualizations of simple viscoelastic systems More
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780185
EISBN: 978-1-62708-281-5
... analyses of viscoelastic plastics are briefly described. The discussion covers the most commonly used tests for impact performance, various types of hardness test for plastics, the fatigue strength of viscoelastic materials, and the tension testing of elastomers and fibers. creep testing dynamic...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2012
DOI: 10.31399/asm.tb.ffub.t53610327
EISBN: 978-1-62708-303-4
..., it covers general characteristics, viscoelastic properties, and static strength. It also discusses fatigue life, impact strength, fracture toughness, and stress-rupture behaviors as well as environmental effects such as plasticization, solvation, swelling, stress cracking, degradation, and surface...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780105
EISBN: 978-1-62708-281-5
... of molecular weight (MW) by viscosity measurements. This is followed by a discussion of the use of cone and plate and parallel plate geometries in determining the viscoelastic properties of a polymer melt. Details on some of the chromatographic techniques that allow determination of MW and MW distribution...
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Published: 01 December 2003
Fig. 23 Mechanical models and typical behavior. (a) Ideal Hookean solid (σ = E ε; spring model; elastic response). (b) Ideal viscous Newtonian liquid (σ = ηε; dashpot model). (c) Maxwell’s mechanical model for a viscoelastic material. (d) Voigt’s mechanical model for a viscoelastic material More
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.tb.tt2.t51060137
EISBN: 978-1-62708-355-3
.... A procedure was initially developed for tests on metals but was subsequently adopted and adapted for tests on rubbers, fibers, and plastics. In the case of plastics, their viscoelastic nature and the probable anisotropy of their end products (including test specimens) are factors that strongly influence both...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 September 2005
DOI: 10.31399/asm.tb.gmpm.t51250077
EISBN: 978-1-62708-345-4
... the intermolecular bonds and the material behaves as a solid. However, these solid materials, to a varying degree, retain some aspects of a liquid in the form of viscoelastic behavior (see the section “Metals versus Plastics” in this chapter). Thermoplastics have greater toughness, or resistance to impact loads...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 2005
DOI: 10.31399/asm.tb.mmfi.t69540297
EISBN: 978-1-62708-309-6
... 4.9 57–80 135–175 Source: Ref 7.8 , 7.9 7.2.1 Viscoelastic Behavior Many polymers exhibit viscoelastic behavior. When viscoelastic polymers are stressed, there is an immediate elastic response. This is followed by viscous flow, which decreases with time until a steady state...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780314
EISBN: 978-1-62708-281-5
... but a manifestation of viscoelasticity, the exact value of the T g depends on the method used to measure it and the rate at which the temperature is changed during the measurement. For this reason, these parameters must be specified when reporting T g measurements and when comparing data of different plastics...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780199
EISBN: 978-1-62708-281-5
.... This region is called linear viscoelastic behavior, for which the important variable is the compliance, or the strain divided by the stress. Polymers such as polyethylene, however, show nonlinear behavior at strains less than 1%. Another form that has been used for F 1 (σ) is: (Eq 3) F 1...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780204
EISBN: 978-1-62708-281-5
... of Fig. 1 is that this type of mechanical response is general for all amorphous polymers and is often referred to as viscoelastic behavior. By changing the time scale or the temperature of the experiment, the apparent modulus of the material is observed to change. These changes are predictable using...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2012
DOI: 10.31399/asm.tb.lmub.t53550325
EISBN: 978-1-62708-307-2
... because of the softening of thermoplastic plastics or degradation of thermosetting plastics. Some plastics degrade when subjected to sunlight, other forms of radiation, and some chemicals. Thermoplastics exhibit viscoelastic properties, which means they creep under relatively low stress levels...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780211
EISBN: 978-1-62708-281-5
... that Hookian behavior can be assumed is not to be realized. Even theories that assume elastic-plastic criteria are inadequate, because they assume plastic behavior at the crack tip and elastic behavior throughout the remainder of the specimen, whereas in the real materials, there is viscoelastic deformation...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780238
EISBN: 978-1-62708-281-5
... deflection conditions. Moreover, the relative placement of fatigue resistance in polymers correlates strongly to whether the tests are performed under adiabatic or isothermal conditions ( Ref 5 ). Thermal Fatigue and Hysteretic Heating Due to the viscoelastic nature of polymeric solids, a portion...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780249
EISBN: 978-1-62708-281-5
... Because polymers are viscoelastic materials, plastic flow is commonly observed when they are fatigued at higher levels of strain. At moderate strain, however, they exhibit mechanical hysteresis. This is due to the energy-dissipative nature of these materials when they undergo cyclic testing. Thus, some...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780343
EISBN: 978-1-62708-281-5
... the dimensional change of a plastic as a function of time or temperature. The thermomechanical properties that have been measured are the T g , softening point, coefficient of linear thermal expansion, heat-deflection temperatures (HDT), creep moduli, creep relaxation, degree of cure, viscoelastic behavior...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 2005
DOI: 10.31399/asm.tb.mmfi.t69540001
EISBN: 978-1-62708-309-6
... strength and stiffness as the degree of crystallinity increases. Conversely, polymers exhibit low strength, low stiffness, and susceptibility to creep when the temperature is above the glass-transition temperature (i.e., when the polymer structure becomes amorphous with pronounced viscoelastic behavior...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780259
EISBN: 978-1-62708-281-5
... to plastic deformation and plowing, elastic deformation energy, and interference and local deformation caused by third bodies ( Ref 4 ). In addition, differences in mechanical properties, such as viscoelasticity, strain-rate sensitivity, and thermal conductivity, may lead to additional friction-generating...