Work, heat and stored energy in compressive plastic deformation of glassy polymers

Salamatina, O. B.; Höhne, G.W.H.; Rudnev, S. N.; Олейник, Э. Ф.

doi:10.1016/0040-6031(94)80110-x

Cited by 34 publications

(32 citation statements)

References 12 publications

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“…The σ-ε diagrams and the dependences of W, Q, and ΔU on strain are similar to experimental ones [5,6,14,[21][22][23][24][25][26][27]49]. Below ε ≈ 1.5-2.5%, the sample shows an elastic (Hookean) response; in this case, the tensile elastic modulus is Е t ≈ 2.3 GPa and the com pressive modulus is Е c ≈ 2.6 GPa.…”

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charsupporting

confidence: 78%

“…In the last 20 years, the results of experiments on the thermodynamics of plastic deformation, even for flexible chain glassy polymers [18,19,[23][24][25][26][27], showed that this process never commences with con formational coil unfolding. Immediately after transi tion to the post Hookean regime of deformation (in glassy polymers, the Hookean regime is usually com pleted at ε > 2-2.5% at T room ), the potential energy of the samples increases; once this process is finished (the energy approaches the stationary limit), a well pronounced yielding and macroscopic plastic flow commence.…”

Section: This Work Was Supported By the Russian Foundation For Basicmentioning

confidence: 99%

“…In a structurally intact state (defect free state) of a glass, plastic flow is prohibited. According to the model of plasticity with strain bearing defects [23], such defects are the main carriers of inelastic strains (displacements) in a glassy material; later, the chain dimensions and conformational set are adjusted locally to the strain stored by the defect [18,19,[23][24][25][26][27]]. It appears that chain adjustment is accomplished through chain uncoiling.…”

Section: This Work Was Supported By the Russian Foundation For Basicmentioning

confidence: 99%

“…During compression, no saturation occurs; however, the rate of energy gain at ε > 25% markedly decreases. For glassy polymers, real deformation experiments show that ΔU approaches its limiting value at ε ≈ 30% during compression and tension [18,19,[23][24][25][26][27].…”

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 99%

“…Important information concerning the limiting stage of the deformation process is provided by the ratio ΔU/W, which is measured in the course of the deformation run [18,19,[23][24][25][26][27]. Ratio ΔU/W plotted against ε is often used for the interpretation of the mechanism of deformation during plastic deformation of solids [18,19,23,24,27,46].…”

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 99%

See 4 more Smart Citations

Plastic deformation of glassy polymethylene: Computer-aided molecular-dynamic simulation

et al. 2010

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Section: Mechanical Characteristics Of Glasses and Thermodynamic Charsupporting

confidence: 78%

Section: This Work Was Supported By the Russian Foundation For Basicmentioning

confidence: 99%

Section: This Work Was Supported By the Russian Foundation For Basicmentioning

confidence: 99%

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 99%

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 99%

See 3 more Smart Citations

Plastic deformation of glassy polymethylene: Computer-aided molecular-dynamic simulation

et al. 2010

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Investigation of nonelastic response of semicrystalline polymers at high strain levels

Pegoretti

Guardini

Migliaresi

et al. 2000

J. Appl. Polym. Sci.

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The nonelastic behavior at high strains of three semicrystalline polymers [i.e., nylon‐6, poly(ethylene terephthalate), and poly(ethylene 2,6‐naphthalenedicarboxylate] was investigated. For all materials, room temperature tensile strain recovery tests revealed the existence of two components of nonelastic deformation: a fast‐relaxing component (called anelastic) and a slow‐relaxing component (usually called plastic). A strain recovery master curve could be constructed for each material from the strain recovery data obtained at various temperatures. The shift factors versus temperature relationship for the strain recovery master curves allowed us to evaluate an activation energy for the nonelastic strain recovery process. These data were then compared with the activation energy for the glass‐transition process evaluated by dynamic mechanical measurements at low strain. The aim of this comparison was to investigate the influence of viscoelasticity on the nonelastic deformation recovery. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1664–1670, 2000

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Plasticity of semicrystalline polyethylenes viewed through the prism of thermodynamics

Олейник

Salamatina

Rudnev

et al. 2012

J of Applied Polymer Sci

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Thermodynamic characteristics such as mechanical work W def and heat Q def of plastic deformation were measured at room temperature for several non-oriented linear high and ultrahigh molecular mass polyethylenes (PEs). The characteristics were registered simultaneously at room temperature active uniaxial compressive loading in the strain interval e def ¼ 0-50% and rate 4 Â 10 À2 min À1 . An isothermal Calvet-type deformation calorimeter was used for the measurements. Changes of the internal energy DU def stored by deformed samples were calculated from W def and Q def according the first law of thermodynamics. It appears that all thermodynamic quantities linearly depends on degree of crystallinity v ¼ 0.5-0.9 (DSC) at conditions of the study. Such behavior of W def , Q def, and DU def had permitted an extrapolation of measured quantities to crystallinities v ¼ 0.0 (pure amorphous phase) and v ¼ 1.0 (pure crystalline phase) and determination of deformation thermodynamic characteristics for each of them. Both phases participate into W def . It appears that the work W cr def , necessary to deform PE crystallites is considerably higher than W am def , the work necessary to deform the amorphous phase. At e def 30% W cr def is 3-4 times higher than W am def and about two times higher at higher strains. From W am def and W cr def stress-strain curves for both phases of PE were withdrawn. Deformation heat of the amorphous phase Q am def is orders of magnitude lower than Q cr def . It reflects the entropic nature of deformation of rubbery amorphous phase of PEs at low e def . The Q cr def originates from a friction during glide of dislocations trough crystallites. Interesting behavior shows the stored energy of cold work DU def ¼ f(v). At strains e def 30%, the stored energy DU am def is a little lower than DU cr def . However, DU am def becomes higher than DU cr def at e def >30%. The ratio DU def /W def ¼ f(e def ) was constructed also. The ratio gives the fraction of W def , which is transformed into the stored energy of cold work DU def at loading. Behavior of several materials: glassy polymers, PE, and crystalline metals were compared in terms of the ratio. At elastic process, the ratio DU def /W def tends to unity for all the materials. Whole W def in this case is converted into DU def . With e def growth dissipative processes appear and deformation heat is evolved. The ratio tends to DU def /W def < 1. Comparison of three mentioned above materials show, that critical stage of their deformation kinetics is nucleation of the inelastic strain carriers (dislocations in crystals, for example). Initiation is completed very early (at e def e y , the yield strain) for crystalline metals and about 92-98% of the expended W def becomes converted into deformation heat at e def ! e y . Plasticity proceeds differently in glassy polymers. Initiation stage continues in glasses for a high strain e def level, usually higher than e y . The curve DU def /W def ¼ f(e def ) for PEs is located between curves characteristic for metals and ...

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Work, heat and stored energy in compressive plastic deformation of glassy polymers

Cited by 34 publications

References 12 publications

Plastic deformation of glassy polymethylene: Computer-aided molecular-dynamic simulation

Plastic deformation of glassy polymethylene: Computer-aided molecular-dynamic simulation

Investigation of nonelastic response of semicrystalline polymers at high strain levels

Plasticity of semicrystalline polyethylenes viewed through the prism of thermodynamics

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