Yielding of polyethylene through propagation of chain twist defects: Temperature, stem length and strain-rate dependence

Nikolov, S.; Raabe, Dierk

doi:10.1016/j.polymer.2005.12.050

Cited by 19 publications

(15 citation statements)

References 29 publications

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“…As a result, the lamellae are prohibited in rotating to a position where the Schmid-factor reaches a maximum, therefore less crystals undergo plastic slip which -in the actual material -means that markedly less dislocations are generated compared to the same material deformed at room temperature, above T g . In such a purely crystallographic picture we can conclude that the amorphous phase is acting similarly to an additional slip system as for instance suggested by Nikolov and Raabe [35]. On a molecular scale, however, the nucleation of new dislocations is also related to molecular relaxations in the crystalline phase.…”

Section: Discussionsupporting

confidence: 58%

Crystalline plasticity in isotactic polypropylene below and above the glass transition temperature

Polt¹,

Spieckermann²,

Wilhelm³

et al. 2015

Express Polym. Lett.

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Abstract. In-situ X-ray diffraction was applied to isotactic polypropylene with a high volume fraction of !-phase (!-iPP) while it has been compressed at temperatures below and above its glass transition temperature T g . The diffraction patterns were evaluated by the Multi-reflection X-ray Profile Analysis (MXPA) method, revealing microstructural parameters such as the density of dislocations and the size of coherently scattering domains (CSD-size). A significant difference in the development of the dislocation density was found compared to compression at temperatures above T g , pointing at a different plastic deformation mechanism at these temperatures. Based on the individual evolutions of the dislocation density and CSD-size observed as a function of compressive strain, suggestions for the deformation mechanisms occurring below and above T g are made.

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Section: Discussionsupporting

confidence: 58%

Crystalline plasticity in isotactic polypropylene below and above the glass transition temperature

Polt¹,

Spieckermann²,

Wilhelm³

et al. 2015

Express Polym. Lett.

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show abstract

“…where m 0 is an attempt frequency [8,18]. Normally, the value of V h is associated with a typical volume required for a molecular shear rearrangement.…”

Section: Resultsmentioning

confidence: 99%

Nearly frictionless transport of glassy solid helium at low temperature regime

Chu¹

2008

Annals of Physics

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“…Such conformational defects are also responsible for translational mobility of chain segments within the crystal, referred to as chain diffusion, and are required for the α‐relaxation process, resulting in reorientation and relaxation of the interlamellar material 32. This approach was further expanded by Nikolov and Raabe,33 who modeled the stress‐induced motion of the chain twist defects within the dislocation core, enabling them to analyze the temperature and strain rate dependence of yield, by directly relating the macroscopic strain rate $\dot{\epsilon}$ to the microscopic slip rate $\dot{\gamma}$ .…”

Section: Introductionmentioning

confidence: 99%

Micromechanics of semicrystalline polymers: Yield kinetics and long‐term failure

Sedighiamiri

Govaert

Kanters

et al. 2012

J Polym Sci B Polym Phys

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The process of plastic deformation in semicrystalline polymers is complicated due to the operation of a variety of mechanisms at different levels and is strongly dependent on their underlying microstructure. The objective of this work is to establish a quantitative relation between the microstructure and the mechanical performance of semicrystalline polymers, as characterized by elasto-viscoplastic deformation. To do that, a micromechanically based constitutive model is used. The model describes the material as an aggregate of two-phase layered composite inclusions, consisting of crystalline lamellae and amorphous layers. The starting point for adding quantitative abilities to the model, in particular for the yield kinetics, is formed by experimental observations on both the yield kinetics and the time-to-failure of polyethylene at different temperatures, which reveal the contribution of two relaxation processes. To predict the thermo-rheologically complex short-term and long-term failure behavior, the crystallographic slip kinetics and the amorphous yield kinetics are re-evaluated, and the Eyring flow rule is modified by adding a temperature shift function. To enable the prediction of both tension and compression, a non-Schmid effect is added to the constitutive relation of each slip system. The creep behavior of polyethylene is then simulated directly using the multiscale, micromechanical model, predicting the time-tofailure, controlled by plastic deformation.

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Yielding of polyethylene through propagation of chain twist defects: Temperature, stem length and strain-rate dependence

Cited by 19 publications

References 29 publications

Crystalline plasticity in isotactic polypropylene below and above the glass transition temperature

Crystalline plasticity in isotactic polypropylene below and above the glass transition temperature

Nearly frictionless transport of glassy solid helium at low temperature regime

Micromechanics of semicrystalline polymers: Yield kinetics and long‐term failure

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