The Yield Behaviour of Glassy Polymers

Bowden, P. B.

doi:10.1007/978-94-010-2355-9_6

Cited by 106 publications

(70 citation statements)

References 57 publications

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“…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. These values approach the known experimental values measured at T room [5,14,23,24,49]. The diagrams illustrating compression and tension clearly show the yield tooth passing its maximum at a tensile strain of ε у ≈ 12-13%.…”

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charsupporting

confidence: 85%

“…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: 77%

“…Energy of stretching of chemical bonds ΔU 12 makes practically no contribu tion to ΔU. The contributions from ΔU 13 and ΔU 14 are nearly equal (≈12.5%) during tensile drawing; during compression, the contributions are ≈25% for ΔU 13 and ≈18% for ΔU 14 .…”

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 95%

“…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%

“…However, since then, the mechanism of deformation of chain macro molecular structures has remained a challenge for many academic studies [4][5][6] and for polymer materials sci ence [7][8][9][10]. Nowadays, polymer science faces prob lems of the physics of deformation of glasses [11][12][13][14][15]. 1 …”

Section: Introductionmentioning

confidence: 99%

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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: 85%

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charsupporting

confidence: 77%

Section: Mechanical Characteristics Of Glasses and Thermodynamic Charmentioning

confidence: 95%

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

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

et al. 2010

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Yield and Crazing in Polymers

O’Connell

McKenna

2004

Encyclopedia of Polymer Science and Technology

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The present article discusses yield and crazing in polymeric materials. After introducing the definitions of stress and strain states, we present a brief summary of the general stress–strain responses for polymers under uniaxial tensile and compressive loading. We introduce the various regimes of behavior, from almost linear elastic through the nonlinear response to rubber‐like behavior. We also include the concepts of necking and cold drawing and the Considère construction for determining whether a material will undergo either of these processes. The history of the development of yield criteria and models is then examined in some details. Yield criteria, which may be considered as macroscopic criteria relating the applied stress state to a critical value for yielding, are first discussed and the modifications for pressure dependence introduced. These criteria, while useful from an engineering point of view in that they offer a method to estimate the likelihood of failure for a given loading situation, provide no insight into the microscopic or molecular mechanisms that give rise to yield. Early theories of yield (eg adiabatic heating and strain induced dilatation), though now considered incorrect, are mentioned in their historical context. A number of models are then presented which consider yield as an activated process. In these models, resistance to yielding is considered as being due to inter‐ and/or intramolecular forces. Application of stress (or the associated strain) affects the energy landscape of the material such that the energy barrier for this resistance is reduced and yield can occur. More complex models are then presented which address not only the yield of the material but the subsequent strain‐softening and strain‐hardening events that are observed. We conclude the section on yield by some brief, general observations on dislocation plasticity, the ultimate shear strength, dilatometry and calorimetry, computer modeling, and finally some discussion of yield in semi‐crystalline materials. The second section of the current chapter discusses the phenomenon of crazing. Crazing is a microscopically localized phenomenon, which involves a large degree of localized plastic deformation. Yet, crazing is generally the precursor to macroscopically brittle failure at low craze densities. An overview of craze morphology is first given to familiarize the reader with the main structural features of crazes. The development of a craze can be conveniently subdivided into three stages—initiation, growth, and failure—and each stage is examined separately. As with the yield section, craze initiation is examined in an historical context and the development of theories considering, variously, a critical cavitation stress, a critical strain, or the presence of inherent microvoids which can grow under the applied local stress or strain are discussed. There is general consensus on the mechanisms for craze growth. Craze tip advance is thought to occur by the Taylor meniscus instability mechanism, while craze thickening is due to the drawing in of material from the bulk–fibril interface. Both these mechanisms are presented and the dependence on, for example, molecular weight and cross‐link density discussed. Craze failure is examined in terms of either fibril failure or failure at the bulk–fibril interface. The section is completed by considering other factors for craze formation and failure (effect of cross‐tie fibrils, environmental‐stress cracking, and fatigue failure).

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Shear Properties of Polymers and Composites

Piggott

2012

Wiley Encyclopedia of Composites

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The yield stress of polymers is pressure dependent, unlike that of metals. So this stress in polymers has to be defined by an inverse rule of mixtures expression. In addition, an overwhelming number of polymers fail by tensile crack propagation when sheared. This is true for most of the polymers used for fiber reinforcement. So the failure of laminates under shear loading is complex, involving some polymer tensile fracture together with some fiber flexure and tensile fracture as well. V notch and two‐rail shear data are given for a range of unidirectional and multidirectional laminates. Shear delamination results are also discussed.

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The Yield Behaviour of Glassy Polymers

Cited by 106 publications

References 57 publications

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

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

Yield and Crazing in Polymers

Shear Properties of Polymers and Composites

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