Further investigation of the dielectric normal mode process in undiluted c
 i
 s-polyisoprene with narrow distribution of molecular weight

Imanishi, Yasuo; Adachi, Keiichiro; Kotaka, Tadao

doi:10.1063/1.455244

Cited by 105 publications

(177 citation statements)

References 25 publications

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“…Including the 4 / 5 factor would yield M e ∼ 4800 or 5400 from the packing model. 32,33 Theoretically the same molecular weight dependence as for the melt viscosity is to be found. They fit reasonably well to the data obtained in this investigation.…”

Section: Resultsmentioning

confidence: 81%

Rheological Properties of 1,4-Polyisoprene over a Large Molecular Weight Range

et al. 2004

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The dynamic viscoelastic properties of anionically polymerized model 1,4-polyisoprene (PI) with 6-8% 3,4 microstructure and in the range of molecular weights between 1.5 × 10 3 and 3.2 × 10 6 g/mol were reanalyzed using linear rheology. Viscosities obtained in the zero shear-rate limit, η0, up to sufficiently high molecular weight PI samples indicated a clear transition to the pure reptation regime. All characteristic molecular weights, dividing the [η 0,M]-interval in three different regimes could be obtained in high accuracy and a new "triangle" is proposed. The experimental data were analyzed in terms of the empirical Winter-relaxation BSW-model description for both dynamic moduli. The BSW parameters are determined and interpreted in terms of the packing model where possible. Limitations of the packing model are detected and discussed. Additionally, the parameters of the assumed distribution of relaxation times are compared to predictions of microscopic dynamic theories and useful correlations made. The publication deals, in part, with a misconception in the literature for estimates of the constraint release contribution. The monomeric friction coefficient 0, determined in this study for the first time rheologically for anionic PI itself agrees with the natural rubber analogue.

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Section: Resultsmentioning

confidence: 81%

Rheological Properties of 1,4-Polyisoprene over a Large Molecular Weight Range

et al. 2004

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“…There, the dielectric relaxation time of one of the matrix polymers, i.e., N ) P and identical chemistry, was observed to scale roughly like τ ∼ N 3.4 in an intermediate molecular weight range, 0.5 e log 10 (N/ N e ) e 2. Figure 7 shows the dielectric relaxation times for PI homopolymer melts [22][23][24] and PMC results for melt like parameters R ) 2.2-3.5 and δ ) 0.05. Both values agree with the estimates given in section 2 and are compatible with the analysis of the self-diffusion data 63 shown in Figure 4.…”

Section: Comparison With Melt and Solution Experimentsmentioning

confidence: 99%

“…This elaboration of the tube model results in a stronger-than-reptation scaling of the internal relaxation time, which is tightly connected to the anomalous frequency dependence of the preterminal wing of the disentanglement process in the shear modulus. 16,17 In experimental studies of shear moduli [19][20][21] and dielectric spectra, [22][23][24] the high-frequency wing of the disentanglement process consistently exhibits a power law frequency dependence, G′′(ωτ D . 1) ∼ ω -x and ′′(ωτ D .…”

Section: Introductionmentioning

confidence: 99%

Polymer-Mode-Coupling Theory of Finite-Size-Fluctuation Effects in Entangled Solutions, Melts, and Gels. 2. Comparison with Experiment

Fuchs

Schweizer

1997

Macromolecules

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The predictions of polymer mode coupling theory for the finite size corrections to the transport coefficients of entangled polymeric systems are tested in comparison with various experimental data. It is found that quantitative descriptions of the viscosities, η, dielectric relaxation time, τ , and diffusion coefficients, D, of polymer melts can be achieved with two microscopic structural fit parameters whose values are in the range expected from independent theoretical or experimental information. An explanation for the (apparent) power law behaviors of η, τ , and D in (chemically distinct) melts for intermediate molecular weights as arising from finite size corrections, mainly the self-consistent constraint release mechanism, is given. The variation of tracer dielectric relaxation times from Rouse to reptationlike behavior upon changes of the matrix molecular weight is analyzed. Self-diffusion and tracer diffusion constants of entangled polymer solutions can be explained as well, if one further parameter of the theory is adjusted. The anomalous scaling of the tracer diffusion coefficients in semidilute and concentrated polystyrene solutions, D ∼ N -2.5 , is predicted to arise due to the spatial correlations of the entanglement constraints, termed "constraint porosity". Extensions of the theory to polymer tracer diffusion through poly(vinyl methyl ether) and polyacrylamide gels provide an explanation of the observation of anomalously high molecular weight scaling exponents in a range where the size of the tracer, Rg, already considerably exceeds the gel pore size, g. IntroductionThe microscopic polymer mode coupling (PMC) theory connects the dynamics of entangled polymeric systems to the underlying equilibrium liquid structure. This description therefore naturally includes corrections arising from the finite molecular weights of tracer or matrix polymers. In the preceding paper, 1 referred to as paper I, the PMC predictions with finite size corrections have been worked out for the transport properties of entangled solutions and melts and for polymer tracer motion in gels. In the present paper these results are compared with data from many experiments. As the PMC approach has been detailed in the preceding paper, 1 it shall be summarized only shortly in this section and then compared to alternative approaches. The resulting formulas of paper I will be referenced by the equation numbers of that paper with a prefix I.The PMC approach of paper I treats the Rouseentangled crossover problem in a simple interpolative manner. The PMC contributions capturing the entanglement corrections are combined with the Rouse, unentangled quantities, see eqs I.52 and I.68 for D, eqs I.55 and I.67 for η, and eqs I.58 and I.70 for τ . Appreciable deviations from the asymptotes for high molecular weights are therefore not explained by corrections of the Rouse dynamics to the asymptotic, entangled motion. In stark contrast to the contour length fluctuation model of Doi, 2,3 the repton model of Rubinstein, 4 and the Rouse-fluc...

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“…More recently, Adachi and coworkers published a series of papers describing dielectric measurements on both the segmental and terminal modes of PI. 6,7 They established that the molecular weight dependence of the dielectric relaxation times was essentially the same as that of the corresponding mechanical relaxation times. They also observed some increase in the breadth of the normal mode peak with increasing molecular weight.…”

Section: Introductionmentioning

confidence: 99%

“…It is for this reason that most of the published dielectric data for the normal mode is limited to low molecular weight polymers. [6][7][8][9][10][11][12][13][14] This problem can be avoided by obtaining dielectric measurements at lower frequencies, using a time domain instrument. This has the additional benefit of providing data at the same frequencies and temperatures as mechanical spectrometers.…”

Section: Introductionmentioning

confidence: 99%

Normal Mode Relaxation in Linear and Branched Polyisoprene

Roland

Bero

1996

Macromolecules

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Dielectric spectroscopy was carried out on linear and three-arm star polyisoprenes (PI). The shape of the normal mode peak differed significantly from the corresponding mechanical terminal relaxation function, although the temperature dependencies measured for the two spectroscopies were similar. This represents a departure from the usual correlation between time and temperature dependencies. In accord with mechanical relaxation data on these same polymers, the normal mode peak is found to be broader and more sensitive to temperature for star-branched PI than for the linear polymer.

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Further investigation of the dielectric normal mode process in undiluted c i s-polyisoprene with narrow distribution of molecular weight

Cited by 105 publications

References 25 publications

Rheological Properties of 1,4-Polyisoprene over a Large Molecular Weight Range

Rheological Properties of 1,4-Polyisoprene over a Large Molecular Weight Range

Polymer-Mode-Coupling Theory of Finite-Size-Fluctuation Effects in Entangled Solutions, Melts, and Gels. 2. Comparison with Experiment

Normal Mode Relaxation in Linear and Branched Polyisoprene

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