Viscosity and self-diffusion coefficient of linear polyethylene

Pearson, Dale S.; Strate, G. Ver; Meerwall, E. von; Schilling, Frederic C.

doi:10.1021/ma00171a044

Cited by 299 publications

(332 citation statements)

References 10 publications

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“…͑A13͒ for t to infinity ͑8.25 and 8.96 cP, respectively, for the first two sets͒. This yields an estimate for the viscosity of, respectively, ϭ7.86 cP ͑first set͒ and ϭ8.38 cP ͑second set͒ for our melt of C 120 H 242 chains at 450 K. Pearson et al 17 have measured the viscosity of n-alkanes and PE as a function of molecular weight at 450 K, although not at the weight of C 120 chains. An interpolation of their data yields exp ϭ13.5 cP.…”

Section: Shear Relaxation Modulus and Viscositysupporting

confidence: 52%

“…Experimentally a stronger N dependence is observed in the unentangled regime (ϰN 1.8 ) because the density and, more important, the segmental friction coefficient increase with increasing N. 17 …”

Section: ͑A10͒mentioning

confidence: 89%

“…Simulations of the NVT ensemble were performed using a weak coupling scheme to a temperature bath of 450 K with a coupling constant of 0.1 ps. 16 The density was set to 0.7614 g/cm 3 , close to the normal pressure density at 450 K. 17 The average pressure from the simulation was pϷ54 atm. For a correct sampling of the pressure tensor autocorrelation it is important to have a fully equilibrated melt in which there is no average stress present.…”

Section: Simulation Model and Methodologymentioning

confidence: 99%

“…2 we present the result of fitting the three independent parameters of the Rouse model to the observed atomic and chain diffusion data. The three fit parameters are the diffusion coefficient of the chain D, the Rouse time 1 , and the number of statistical segments N. In the Rouse model, the center of mass of a chain will always 3 Pearson et al 17 have measured self-diffusion coefficients by means of field gradient NMR at 450 K experimentally for a large range of molecular weights, although not at the weight of C 120 chains. An interpolation of their data yields D exp Ϸ0.67ϫ10 Ϫ6 cm 2 /s.…”

Section: A Mean Square Displacementmentioning

confidence: 99%

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Zero-shear stress relaxation and long time dynamics of a linear polyethylene melt: A test of Rouse theory

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Briels

2001

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 Results of united atom molecular dynamics simulations of a n-C 120 H 242 melt at 450 K are presented. It is shown that the results of mean square displacement, dynamic structure factor, end-to-end vector autocorrelation, and shear relaxation modulus can consistently be described by the Rouse model with a single set of fit parameters, provided the length scales involved are larger than the statistical segment length bϷ1.2 nm. On smaller length scales the stiffness of the chain becomes prominent, and the results deviate increasingly from the Rouse predictions. The shear relaxation modulus G(t) is determined from the stress autocorrelation function from both atomic and molecular points of view. The integrals ͐G(t)dt are found to be identical after 1 ps and a Rouse description is shown to coincide for time scales larger than 0.4 ns. Compared to experimental values, the measured diffusion coefficient is overestimated by 63% and the viscosity is underestimated by 38%, consistent with molecular dynamics simulations of small molecules.

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Section: Shear Relaxation Modulus and Viscositysupporting

confidence: 52%

Section: ͑A10͒mentioning

confidence: 89%

Section: Simulation Model and Methodologymentioning

confidence: 99%

Section: A Mean Square Displacementmentioning

confidence: 99%

See 2 more Smart Citations

Zero-shear stress relaxation and long time dynamics of a linear polyethylene melt: A test of Rouse theory

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Briels

2001

The Journal of Chemical Physics

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“…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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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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