Confirmation of Plazek's Slight Shoulder in the Shear Retardation Spectrum of Poly(vinyl acetate) at the Dynamic Glass Transition

Reissig, S.; Beiner, Mario; Korus, Jarosław; Schroeter, K.; Donth, E.

doi:10.1021/ma00119a038

Cited by 9 publications

(25 citation statements)

References 1 publication

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“…Plazek suggested that there might be shoulder in retardation spectrum. This was confirmed by Reissig et al 18 and Ngai et al 19 Our calculated J* varies with temperature and, hence, the retardation spectra may have a shoulder at low temperatures.…”

Section: Comparison With Previous Studiessupporting

confidence: 83%

Viscoelasticity of low molecular weight polystyrene. Separation of rubbery and glassy components

Inoue

Onogi

Yao

et al. 1999

J. Polym. Sci. B Polym. Phys.

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The complex shear modulus was measured for four low molecular‐weight polystyrenes (Mw = 10,500, 5970, 2630, and 1050) near and above the glass transition temperature. For the lowest molecular weight sample, the method of reduced variables, the time–temperature superposition principle, was applicable, while it was not applicable for the higher M samples. For these higher M samples, it was assumed that the complex modulus is composed of two components (R and G components). The R component was estimated by subtracting the G component, which was assumed to be the same as the modulus of the lowest molecular weight sample. The time–temperature superposition principle was applicable to each of the R and G components, and the shift factors were different from each other. The contribution of the R component to the total complex modulus decreased with decreasing M. Anomalous temperature dependence of the steady‐state compliance for low M polymers as Plazek reported could be attributed to difference in temperature dependence of the two components. The estimated complex modulus for the R component was in accord with that calculated by spring‐bead model theory. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 389–397, 1999

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Section: Comparison With Previous Studiessupporting

confidence: 83%

Viscoelasticity of low molecular weight polystyrene. Separation of rubbery and glassy components

Inoue

Onogi

Yao

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…These data of L (τ/ a T ) from refs. 52 and 53 exhibit a shoulder at L (τ/ a T ) ≈ −9.25 Pa −1 , which suggests the contribution from the segmental α‐relaxation is given by the smallest peak (open triangles) in the figure.…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

“…Two experimental facts have helped to isolate the segmental α‐relaxation and to determine its contribution to the compliance. One is from the appearance of a shoulder in the shear retardation spectrum, L (λ), of a high‐molecular‐weight PS 52–54 . L (λ) is related to the creep compliance J ( t ) by where λ is the retardation time.…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

“…With the assistance of dielectric and enthalpy relaxation measurements, Donth and coworkers52–54 have identified the shoulder originating from the termination of the contribution to L (λ) from the segmental α‐relaxation, which is responsible for glass transition at T g . The shoulder also was found by Plazek in L (λ) of PS, PVAc,56 and atactic polypropylene,57 by Grassia et al in the relaxation spectra of PS Dylene 858(a) and PC58(b‐c), and by Guo et al in L (λ) of star‐PS 58(d).…”

Section: Molecular Motions In the Softening Dispersion Of Bulk Polymersmentioning

confidence: 99%

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Viscoelasticity of nanobubble‐inflated ultrathin polymer films: Justification by the coupling model

Ngai

Prevosto

Grassia

2012

J Polym Sci B Polym Phys

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The nanobubble inflation method is the only experimental technique that can measure the viscoelastic creep compliance of unsupported ultrathin films of polymers over the glass-rubber transition zone as well as the dependence of the glass transition temperature (T g ) on film thickness. Sizeable reduction of T g was observed in polystyrene (PS) and bisphenol A polycarbonate by the shift of the creep compliance to shorter times. The dependence of T g on film thickness is consistent with the published data of free-standing PS ultrathin films. However, accompanying the shift of the compliance to shorter times, a decrease in the rubbery plateau compliance is observed. The decrease becomes more dramatic in thinner films and at lower temperatures. This anomalous viscoelastic behavior was also observed in poly(vinyl acetate) and poly (n-butyl methacrylate), but with large variation in the change of either the T g or the plateau compliance. By now, well established in bulk polymers is the presence of three different viscoelastic mechanisms in the glass-rubber transition zone, namely, the Rouse modes, the sub-Rouse modes, and the segmental a-relaxation. Based on the thermorheological complexity of the three mechanisms, the viscoelastic anomaly observed in ultrathin polymer films and its dependence on chemical structure are explained in the framework of the Coupling Model.Next, the softening dispersion of PBMA had been obtained by the measurements of the complex shear compliance (J* ¼ J 0 À J 00 ) in the frequency range from 24 to 2400 cycles by Child and Ferry. 79 Both J 0 and J 00 show very broad width of

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“…This will be followed by a comparison of the creep and dynamic data. While a shoulder appears in the L of D, − there is no trace of it in the L derived from the recoverable creep compliance of PS . The shoulder in L of D enables the isolation of the local segmental contribution to the recoverable compliance.…”

Section: Introductionmentioning

confidence: 96%

Viscoelastic Properties of Amorphous Polymers. 6. Local Segmental Contribution to the Recoverable Compliance of Polymers

1996

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A prominent shoulder exhibited in the shear retardation spectrum of a high molecular weight polystyrene enables the local segmental contribution to the recoverable compliance to be isolated and determined for the first time. The prominence of this shoulder depends on the time/frequency window of the viscoelastic measurements. This interesting dependence is explained by the thermorheological complexity of the glass−rubber softening dispersion.

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Confirmation of Plazek's Slight Shoulder in the Shear Retardation Spectrum of Poly(vinyl acetate) at the Dynamic Glass Transition

Cited by 9 publications

References 1 publication

Viscoelasticity of low molecular weight polystyrene. Separation of rubbery and glassy components

Viscoelasticity of low molecular weight polystyrene. Separation of rubbery and glassy components

Viscoelasticity of nanobubble‐inflated ultrathin polymer films: Justification by the coupling model

Viscoelastic Properties of Amorphous Polymers. 6. Local Segmental Contribution to the Recoverable Compliance of Polymers

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