Retraction of Stressed Rubber

Mrowca, B. A.; Guth, Eugene

doi:10.1103/physrev.66.30.2

Cited by 16 publications

(6 citation statements)

References 3 publications

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“…12 All-atom molecular dynamics (MD) simulations 13 of isolated polybutadiene molecules have shown that the diffusion mechanism (that produces the chain end-to-end distance distribution) is at least several orders of magnitude too slow to account for the high snap-back velocities observed in experiments. [14][15][16] There is also some evidence that a discontinuity in the modulus exists between tensile and compressive strain, 17 which is contrary to the predictions of current models.…”

Section: Introductioncontrasting

confidence: 71%

The molecular kink paradigm for rubber elasticity: Numerical simulations of explicit polyisoprene networks at low to moderate tensile strains

Hanson

2011

The Journal of Chemical Physics

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Based on recent molecular dynamics and ab initio simulations of small isoprene molecules, we propose a new ansatz for rubber elasticity. We envision a network chain as a series of independent molecular kinks, each comprised of a small number of backbone units, and the strain as being imposed along the contour of the chain. We treat chain extension in three distinct force regimes: (Ia) near zero strain, where we assume that the chain is extended within a well defined tube, with all of the kinks participating simultaneously as entropic elastic springs, (II) when the chain becomes sensibly straight, giving rise to a purely enthalpic stretching force (until bond rupture occurs) and, (Ib) a linear entropic regime, between regimes Ia and II, in which a force limit is imposed by tube deformation. In this intermediate regime, the molecular kinks are assumed to be gradually straightened until the chain becomes a series of straight segments between entanglements. We assume that there exists a tube deformation tension limit that is inversely proportional to the chain path tortuosity. Here we report the results of numerical simulations of explicit three-dimensional, periodic, polyisoprene networks, using these extension-only force models. At low strain, crosslink nodes are moved affinely, up to an arbitrary node force limit. Above this limit, non-affine motion of the nodes is allowed to relax unbalanced chain forces. Our simulation results are in good agreement with tensile stress vs. strain experiments.

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Section: Introductioncontrasting

confidence: 71%

The molecular kink paradigm for rubber elasticity: Numerical simulations of explicit polyisoprene networks at low to moderate tensile strains

Hanson

2011

The Journal of Chemical Physics

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“…Efforts have been made to characterise the loading [1] and fracture [2,3] properties of rubbers at very high strain rates, whereas the characterisation of rapid unloading of rubber has received less attention. A number of papers have addressed rapid unloading by examining the free retraction of rubber -where rubber is deformed and then released [4][5][6][7][8][9][10][11], or released from tension post-fracture e.g. after the bursting of a rubber balloon [12].…”

Section: Introductionmentioning

confidence: 99%

“…Mrowca, Dart and Guth [4,5] noted that when released from moderate extensions, tensile retraction of rubber strips proceeds via a retraction pulse which travels through the material at a velocity, , relaxing the strained portion as it proceeds. A schematic of this free retraction process is given in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

The free retraction of natural rubber: A momentum-based model

2015

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The free retraction of vulcanised strips of natural rubber released from simple uniaxial deformations is studied using high speed cinematography in the context of a simple momentum theory. A good agreement between the theory and experiment is observed when vulcanisates are released from stresses below 1 MPa which corresponds to tensile strains rates below 1x10 3 s-1. Above this critical stress and corresponding strain rate value, an increasing dispersion is observed in the form of a slowing down of the characteristic retraction pulse and also by a relaxation of strain ahead of the pulse front (a dispersion of the pulse). Holding samples at high strains for an extended period of time prior to releasing results in a further, significant retardation of the retraction pulse velocity. These effects are related to the increasing non-linearity of high strain rate retraction stress-strain behaviour. Energy balance arguments show that the dispersion of the retraction pulse is a prerequisite for pulse propagation and its magnitude underpins the deviation from the momentum model outlined in this paper.

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“…The rapid retraction of a stretched rubber sample as one end is abruptly released, is commonly referred to as 'snapback' and quantitative measurements of the speed of both the free end and intermediate points along the sample have been reported [51][52][53][54][55][56][57][58]. There are several surprising results from these experiments.…”

Section: Other Relevant Experimentsmentioning

confidence: 80%