Void nucleation and disentanglement in glassy amorphous polymers

Mahajan, Dhiraj K.; Singh, Birbal; Basu, S.

doi:10.1103/physreve.82.011803

Cited by 44 publications

(28 citation statements)

References 29 publications

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“…Next, voids grow, coalesce, and the ligaments between the voids are subsequently super drawn, which results in the typical structure of a craze, consisting of a crack-like defect bridged by highly drawn filaments (fibrils). It is well known that the initiation and development of a local plastic zone is dominated by the post-yield characteristics of the polymer material [46][47][48][49]. Generally, for a polymer material, the post-yield behaviour is governed by two phenomena: (1) strain softening, leading to the initiation of strain localisation, and (2) strain hardening, stabilizing the growth of the localised plastic zone.…”

Section: Discussionmentioning

confidence: 99%

“…Based on the theories from McMeeking [45], the crack tip opening displacement (CTOD) during small-scale yielding is proportional to the applied J-integral. It is, therefore, of interest to examine the crazing process: craze nucleation, growth and development into cracks during the deformation process of polymer materials [46][47][48][49][50][51], since it contributes to the plastic zone ahead of the crack.…”

Section: Discussionmentioning

confidence: 99%

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Dynamic compressive mechanical response of a soft polymer material

2015

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Dynamic compressive mechanical response of a soft polymer material

2015

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“…The entanglement environment is collective, and certain binary interactions are more important than others. Thus, under nonlinear deformation or flow, where some kind of entanglement network evolution takes place (due to CR), it is possible that changes in the number of detected kinks 75,118,119 do not reflect the actual microscopic changes of the entangled state of the system.…”

Section: Discussionmentioning

confidence: 99%

Microscopic Description of Entanglements in Polyethylene Networks and Melts: Strong, Weak, Pairwise, and Collective Attributes

2012

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Abstract:We present atomistic molecular dynamics simulations of two Polyethylene systems where all entanglements are trapped: a perfect network, and a melt with grafted chain ends. We examine microscopically at what level topological constraints can be considered as a collective entanglement effect, as in tube model theories, or as certain pairwise uncrossability interactions, as in slip-link models.A pairwise parameter, which varies between these limiting cases, shows that, for the systems studied, the character of the entanglement environment is more pairwise than collective. We employ a novel methodology, which analyzes entanglement constraints into a complete set of pairwise interactions, similar to slip links. Entanglement confinement is assembled by a plethora of links, with a spectrum of confinement strengths, from strong to weak. The strength of interactions is quantified through a link 'persistence', which is the fraction of time for which the links are active. By weighting links according to their strength, we show that confinement is imposed mainly by the strong ones, and that the weak, trapped, uncrossability interactions cannot contribute to the low frequency modulus of an elastomer, or the plateau modulus of a melt. A selfconsistent scheme for mapping topological constraints to specific, strong binary links, according to a given entanglement density, is proposed and validated. Our results demonstrate that slip links can be viewed as the strongest pairwise interactions of a collective entanglement environment. The methodology developed provides a basis for bridging the gap between atomistic simulations and mesoscopic slip link models.

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“…More recent simulations explored correlations between the location of failure and regions of higher mobility or higher chain ends density that might act as local defects, [10] or a local stress-induced disentanglement of chains. [11] In the latter work a primitive path algorithm was used to monitor the entanglement network in a sample undergoing triaxial deformation, and it was found that regions undergoing crazing were also depleted in terms of entanglements. The local mechanical properties are a determining factor to understand the response of systems under strain.…”

Section: Introductionmentioning

confidence: 99%

Predictors of Cavitation in Glassy Polymers under Tensile Strain: A Coarse‐Grained Molecular Dynamics Investigation

Makke

Perez

Rottler

et al. 2011

Macro Theory & Simulations

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The nucleation of cavities in a homogenous polymer under tensile strain is investigated in a coarse-grained molecular dynamics simulation. In order to establish a causal relation between local microstructure and the onset of cavitation, a detailed analysis of some local properties is presented. In contrast to common assumptions, the nucleation of a cavity is neither correlated to a local loss of density nor, to the stress at the atomic scale and nor to the chain ends density in the undeformed state. Instead, a cavity in glassy polymers nucleates in regions that display a low bulk elastic modulus. This criterion allows one to predict the cavity position before the cavitation occurs. Even if the localization of a cavity is not directly predictable from the initial configuration, the elastically weak zones identified in the initial state emerge as favorite spots for cavity formation.

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Void nucleation and disentanglement in glassy amorphous polymers

Cited by 44 publications

References 29 publications

Dynamic compressive mechanical response of a soft polymer material

Dynamic compressive mechanical response of a soft polymer material

Microscopic Description of Entanglements in Polyethylene Networks and Melts: Strong, Weak, Pairwise, and Collective Attributes

Predictors of Cavitation in Glassy Polymers under Tensile Strain: A Coarse‐Grained Molecular Dynamics Investigation

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