Evolution in concepts concerning the mechanism of plasticity in solid polymers after the 1950s

Олейник, Э. Ф.; Rudnev, S. N.; Salamatina, O. B.

doi:10.1134/s0965545x07120073

Cited by 52 publications

(71 citation statements)

References 58 publications

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“…However, in all the above cited publications, growth in the potential energy of a polymer glass during its deformation has been neglected, while structures responsible for this growth have not been identified. This outcome is odd because, in this approach, all authors ignored the main process, which seems to be the central stage responsible for the macroscopic plasticity in glassy macromolecular materials [18,19].…”

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

confidence: 99%

“…[4-6, 14, 16, 18, 19]. This circumstance suggests that the concept of low temperature plasticity in glasses should be supple mented with some crystal like features [19,20]. At present, the adopted standpoint is that, in mac romolecular glasses, plasticity likewise proceeds via the mechanism of viscous flow of liquids [11,13,15]; however, this process is aggravated by the uncoiling of polymer coils [21,22].…”

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

confidence: 99%

“…However, this model has failed to explain many features of this process [4,6,10,14,[18][19][20], including the above mentioned crystal like features of deforma tion [18,19] and the deformation of glasses composed of rigid macromolecules, which are appreciably extended before deformation. Evidently, chains with low and medium rigidity can be unfolded and disen tangled without any ruptures at high strains under all regimes of loading.…”

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

confidence: 99%

“…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%

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

confidence: 99%

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

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Preparation and properties of high performance phthalide‐containing bismaleimide modified epoxy matrices

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et al. 2011

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A series of intercrosslinked networks formed by diglycidyl ether of bisphenol A epoxy resin (DGEBA) and novel bismaleimide containing phthalide cardo structure (BMIPP), with 4,4 0 -diamino diphenyl sulfone (DDS) as hardener, have been investigated in detail. The curing behavior, thermal, mechanical and physical properties and compatibility of the blends were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), notched Izod impact test, scanning electron microscopy (SEM) and water absorption test. DSC investigations showed that the exothermic transition temperature (T p ) of the blend systems shifted slightly to the higher temperature with increasing BMIPP content and there appeared a shoulder on the high-temperature side of the exothermic peak when BMIPP content was above 15 wt %. TGA and DMA results indicated that the introduction of BMIPP into epoxy resin improved the thermal stability and the storage modulus (G 0 ) in the glassy region while glass transition temperature (T g ) decreased.Compared with the unmodified epoxy resin, there was a moderate increase in the fracture toughness for modified resins and the blend containing 5 wt % of BMIPP had the maximum of impact strength. SEM suggested the formation of homogeneous networks and rougher fracture surface with an increase in BMIPP content. In addition, the equilibrium water uptake of the modified resins was reduced as BMIPP content increased.

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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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Evolution in concepts concerning the mechanism of plasticity in solid polymers after the 1950s

Cited by 52 publications

References 58 publications

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

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

Preparation and properties of high performance phthalide‐containing bismaleimide modified epoxy matrices

Plasticity of semicrystalline polyethylenes viewed through the prism of thermodynamics

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