A time-integrated estimate of the entanglement mass in polymer melts in agreement with the one determined by time-resolved measurements

Padding, JT Johan; Briels, Willem J.

doi:10.1063/1.1640348

Cited by 19 publications

(22 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…At this point, it should be noted that the value of M e strongly depends on the approach adopted for its calculation. Padding and Briels [159] already observed that all methods based on time-resolved quantities, such as the dynamic structure factor, S(q,t) and the relaxation modulus, G(t), nearly give the same result. Such a value is around 1.5 higher than that obtained from the "plateau" modulus, G N 0 , which is a time-integrated quantity.…”

Section: Topological Analysis: Primitive Paths and Entanglementsmentioning

confidence: 91%

Predicting experimental results for polyethylene by computer simulation

Ramos

Vega

Martínez‐Salazar

2018

European Polymer Journal

View full text Add to dashboard Cite

This feature article reviews several aspects of computational approaches to polyethylene melt and solid state properties in relation to existing experimental results. Based on 40 years of experience in the field, we offer a personal view of how computer simulations are helping to understand the physics of polyethylene as a model polymer. The first issue discussed is the molten state of polyethylene, including static and dynamic properties and entanglement features along with their impacts on rheological behaviour. We then examine the glass transition, crystallization process and solid state structure, including the interlamellar region. This is followed by brief descriptions of the latest advances in simulating mechanical properties and of the various methodologies used to simulate the physics of polyethylene. Throughout the manuscript, references are made to our own work and also to studies by many other authors that have nicely contributed to developments in simulating the physics of polyethylene in close agreement with experimental results.

show abstract

Section: Topological Analysis: Primitive Paths and Entanglementsmentioning

confidence: 91%

Predicting experimental results for polyethylene by computer simulation

Ramos

Vega

Martínez‐Salazar

2018

European Polymer Journal

View full text Add to dashboard Cite

show abstract

“…It is typically O͑10-100͒ persistence lengths. 17,18 This means that the simulation box must contain at least O͑10 4 ͒ persistence lengths. One persistence length of wormlike micelle contains O͑10 3 ͒ surfactant molecules, 12 leading to O͑10 7 ͒ surfactant molecules in total.…”

Section: Figmentioning

confidence: 99%

Dynamics and rheology of wormlike micelles emerging from particulate computer simulations

Padding

Boek²,

Briels³

2008

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

We perform coarse-grained computer simulations of solutions of semidilute wormlike micelles and study their dynamic and rheological properties, both in equilibrium and under shear flow. The simulation model is tailored to the study of relatively large time and length scales (micrometers and several milliseconds), while it still retains the specific mechanical properties of the individual wormlike micelles. The majority of the mechanical properties (persistence length, diameter, and elastic modulus of a single worm) is determined from more detailed atomistic molecular dynamics simulations, providing the link with the chemistry of the surfactants. The method is applied to the case of a solution containing 8% (by weight) erucyl bis(hydroxymethyl)methylammonium chloride (EHAC). Different scission energies ranging from 15.5k(b)T to 19.1k(B)T are studied, leading to both unentangled and entangled wormlike micelles. We find a decrease in the average contour length and an increase in the average breaking rate with increasing shear rate. In equilibrium, the decay of the shear relaxation modulus of the unentangled samples agrees with predictions based on a theory of breakable Rouse chains. Under shear flow, transient over- and undershoots are measured in the stress tensor components. At high shear rates we observe a steady-state shear stress proportional to gamma(1/3), where gamma is the shear rate. This is confirmed by our high shear rate experiments of real EHAC in a parallel-plate geometry.

show abstract

“…(5), may be too crude and more elaborate choices can be made. Furthermore, some of the discrepancy may also be attributed to a recently reported inconsistency of the tube model, in which the tube diameter extracted from rheology is different from the value obtained from neutron spin echo or diffusion measurements [23,24]. In fact, fitting the data at t 0 with the Warner-Edwards model, where the tube diameter is a free fitting parameter, suggests a value 4n m .…”

mentioning

confidence: 96%

Small Angle Neutron Scattering Observation of Chain Retraction after a Large Step Deformation

et al. 2005

View full text Add to dashboard Cite

Article:Blanchard, A., Graham, R.S., Heinrich, M. et The process of retraction in entangled linear chains after a fast nonlinear stretch was detected from time-resolved but quenched small angle neutron scattering (SANS) experiments on long, well-entangled polyisoprene chains. The statically obtained SANS data cover the relevant time regime for retraction, and they provide a direct, microscopic verification of this nonlinear process as predicted by the tube model. Clear, quantitative agreement is found with recent theories of contour length fluctuations and convective constraint release, using parameters obtained mainly from linear rheology. The theory captures the full range of scattering vectors once the crossover to fluctuations on length scales below the tube diameter is accounted for. Both fundamental and applied understanding of polymer dynamics through the use of molecular based theories has seen rapid progress in the past 20 years [1]. This progress stems from the realization that surrounding chains severely limit global motion of a test chain in directions perpendicular to its contour but do not prohibit motion along it, confining each chain to a tubelike region defined by its own contour [2]. This physical picture is beautifully cast into a physical theory by the reptation model of de Gennes [3]. The current challenge is to augment this concept of onedimensional diffusion of a chain along a tube into a quantitative molecular approach describing both the linear and nonlinear rheological properties as well as the underlying molecular motions [4 -6].One important question in this context relates to the chain relaxation in elongational flow. A large step extensional elongation is expected to affinely deform the chain contour. This will cause the chain radius of gyration parallel to the flow to increase and conversely the one in the perpendicular direction to decrease. After cessation of the strain, one expects the first relaxation process to be a retraction of the chain within the still affinely deformed tube. The longest time scale of this process should be the equilibration time R (Rouse time) of the chain along the tube. This mechanism is related by a fluctuationdissipation theorem to the chain contour length fluctuations, entropically driven extension and retraction of the chain contour which recently was corroborated directly on a molecular level [7].Chain retraction in the elongated tube should reduce the radius of gyration in all directions. Therefore R perp g is expected to attain a minimum, manifested as an increase in perpendicular scattered intensity, at some time after the deformation determined by the Rouse time, before diffusive mechanisms return it to equilibrium. This nonmonotonic behavior, with the minimum at a time consistent with the time scale of Rouse chain retraction, was not observed in previous experiments on polystyrene [8,9] and poly(ethylethylene) melts [10]. The requirement of a measurable Rouse time demanded prohibitively large overall chain dimensions so observations were pos...

show abstract

A time-integrated estimate of the entanglement mass in polymer melts in agreement with the one determined by time-resolved measurements

Cited by 19 publications

References 23 publications

Predicting experimental results for polyethylene by computer simulation

Predicting experimental results for polyethylene by computer simulation

Dynamics and rheology of wormlike micelles emerging from particulate computer simulations

Small Angle Neutron Scattering Observation of Chain Retraction after a Large Step Deformation

Contact Info

Product

Resources

About