Viscosity and self-diffusion coefficient of hydrogenated polybutadiene

Pearson, Dale S.; Fetters, Lewis J.; Graessley, William W.; Strate, G. Ver; Meerwall, E. von

doi:10.1021/ma00081a014

Cited by 202 publications

(236 citation statements)

References 17 publications

(31 reference statements)

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“…No transition is observed at the molecular weight M e,r itself, not under constant pressure nor under constant density conditions. The reason why the transition does not occur at M e,r is that there are additional molecular relaxation processes besides those in the original reptation model, and that the Kuhn segment density is still increasing in the region where the transition should occur, as was already noticed by Pearson et al 10 Similarly, the exponent in the scaling of the viscosity has a transition at a molecular weight, which is much larger than M e,r . This molecular weight is usually referred to as the critical molecular weight M c ͓4 -5 kg/mol for PE ͑Ref.…”

Section: Time-integrated Resultsmentioning

confidence: 85%

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

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Briels

2004

The Journal of Chemical Physics

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Effects of alignment layer thickness on the pretilt angle of liquid crystals APL: Org. Electron. Photonics 3, 270 (2010) Effects of alignment layer thickness on the pretilt angle of liquid crystals Appl. Phys. Lett. 97, 243306 (2010) Field-theoretic model of inhomogeneous supramolecular polymer networks and gels J. Chem. Phys. 133, 174903 (2010) Origin of translocation barriers for polyelectrolyte chains JCP: BioChem. Phys We make a critical examination of how the entanglement molecular mass M e is determined from various measurable quantities. We are guided by reptation theory, where it is assumed that characteristic relaxations abruptly change and become equal to those of a chain moving in a Gaussian tube, as soon as the corresponding length scales surpass the tube diameter d or similarly as soon as the corresponding mass surpasses a critical value. Taking this critical mass as a definition of the ''reptational'' entanglement mass, we observe that all methods based on time-resolved quantities, such as the single-chain dynamic structure factor S(q,t) and the zero-shear relaxation modulus G(t), give the same result. We observe that such a value differs, beyond error bars, from that obtained from the plateau modulus, which is a time-integrated quantity. We have investigated an alternative definition of entanglement mass in terms of time-integrated quantities and observe that the value of this specific entanglement mass is consistent with that obtained from the time-resolved observables. We comment on possible reasons for the plateau modulus discrepancy.

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Section: Time-integrated Resultsmentioning

confidence: 85%

“…Let us note that the combination of viscosity and selfdiffusion coefficient was already investigated by Pearson et al 9,10 No attempt was made, however, to derive the entanglement mass from the high molecular weight data. Rather, they used the ''rubbery'' value based on the plateau modulus to test the reptation theory prediction…”

Section: Discussionmentioning

confidence: 99%

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

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Briels

2004

The Journal of Chemical Physics

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“…One concludes that the agreement is satisfactory, and in some sense, the incoherent structure factor provides information about entanglements similar to that of the coherent one. Now we predict plateau modulus, viscosity, and diffusion coefficients to compare them to the data by Pearson et al 18 All stresses calculated in simulations must be multiplied by G 0 ) FRT/M 0 , viscosities by G 0 τ 0 , and diffusion coefficients by b sim 2 /τ 0 . The data in ref 18 are given for T ) 448 K, and we calculate τ 0 (T ) 448 K) ) 0.14 ns using shift factors given in the same paper.…”

Section: Polyethylene (Pe)mentioning

confidence: 99%

Single-Chain Slip-Link Model of Entangled Polymers: Simultaneous Description of Neutron Spin−Echo, Rheology, and Diffusion

2005

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The model presented in this paper describes simultaneously three different experimental techniques applied to different monodisperse polymer melts: neutron spin-echo (NSE), linear rheology, and diffusion. First, it shows that the standard tube model cannot be applied to NSE because the statistics of a one-dimensional (1D) chain in a three-dimensional (3D) random-walk tube become wrong on the length scale of the tube diameter, whereas all available NSE data are for scattering vectors in this range. Then a new single-chain dynamic slip-link model on the basis of a recent network model by Rubinstein and Panyukov is introduced. Instead of solving the model analytically, which would require uncontrolled approximations, the model is formulated in terms of stochastic differential equations, suitable for Brownian dynamics simulations. I perform these simple simulations, demonstrate that the model describes individual experiments well, and then compare the results with experiments on monodisperse polyethylene, polyethylene-propylene, polyisoprene, polybutadiene, and polystyrene. For all polymers, model parameters from one experiment are obtained, and the others are predicted without fitting. The results show some systematic discrepancies, suggesting possible inadequacy of the Gaussian chain model for some of the polymers, and possible inadequacy of time-temperature superposition.

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“…Figure 9 compares the zero shear rate viscosities obtained from our PP analysis with reported experimental data [33][34][35][36][37] for a number of model PE ͓Fig. 9͑a͔͒ and PB ͓Fig.…”

Section: -8mentioning

confidence: 99%

Quantifying chain reptation in entangled polymer melts: Topological and dynamical mapping of atomistic simulation results onto the tube model

Stephanou

Baig

Tsolou

et al. 2010

The Journal of Chemical Physics

106

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Articles you may be interested inTemperature dependent micro-rheology of a glass-forming polymer melt studied by molecular dynamics simulation J. Chem. Phys. 141, 124907 (2014) The topological state of entangled polymers has been analyzed recently in terms of primitive paths which allowed obtaining reliable predictions of the static ͑statistical͒ properties of the underlying entanglement network for a number of polymer melts. Through a systematic methodology that first maps atomistic molecular dynamics ͑MD͒ trajectories onto time trajectories of primitive chains and then documents primitive chain motion in terms of a curvilinear diffusion in a tubelike region around the coarse-grained chain contour, we are extending these static approaches here even further by computing the most fundamental function of the reptation theory, namely, the probability ͑s , t͒ that a segment s of the primitive chain remains inside the initial tube after time t, accounting directly for contour length fluctuations and constraint release. The effective diameter of the tube is independently evaluated by observing tube constraints either on atomistic displacements or on the displacement of primitive chain segments orthogonal to the initial primitive path. Having computed the tube diameter, the tube itself around each primitive path is constructed by visiting each entanglement strand along the primitive path one after the other and approximating it by the space of a small cylinder having the same axis as the entanglement strand itself and a diameter equal to the estimated effective tube diameter. Reptation of the primitive chain longitudinally inside the effective constraining tube as well as local transverse fluctuations of the chain driven mainly from constraint release and regeneration mechanisms are evident in the simulation results; the latter causes parts of the chains to venture outside their average tube surface for certain periods of time. The computed ͑s , t͒ curves account directly for both of these phenomena, as well as for contour length fluctuations, since all of them are automatically captured in the atomistic simulations. Linear viscoelastic properties such as the zero shear rate viscosity and the spectra of storage and loss moduli obtained on the basis of the obtained ͑s , t͒ curves for three different polymer melts ͑polyethylene, cis-1,4-polybutadiene, and trans-1,4-polybutadiene͒ are consistent with experimental rheological data and in qualitative agreement with the double reptation and dual constraint models. The new methodology is general and can be routinely applied to analyze primitive path dynamics and chain reptation in atomistic trajectories ͑accumulated through long MD simulations͒ of other model polymers or polymeric systems ͑e.g., bidisperse, branched, grafted, etc.͒; it is thus believed to be particularly useful in the future in evaluating proposed tube models and developing more accurate theories for entangled systems.

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Viscosity and self-diffusion coefficient of hydrogenated polybutadiene

Cited by 202 publications

References 17 publications

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

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

Single-Chain Slip-Link Model of Entangled Polymers: Simultaneous Description of Neutron Spin−Echo, Rheology, and Diffusion

Quantifying chain reptation in entangled polymer melts: Topological and dynamical mapping of atomistic simulation results onto the tube model

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