Determination of the relaxation spectrum from oscillatory shear data

Orbey, Neşe; Dealy, John M.

doi:10.1122/1.550164

Cited by 92 publications

(49 citation statements)

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“…The least-squares principle was applied to determine the values of G i . 20 The following sum in eq. (12) was calculated:…”

Section: Relaxation Times Distributionmentioning

confidence: 99%

“…In this study, the linear least-squares method 20 was used to obtain the relaxation time and the relaxation modulus. N sets of model parameters (G i , i ) were determined by using the experimental sets of data [GЈ(w j ), GЉ(w j )] with eqs.…”

Section: Relaxation Times Distributionmentioning

confidence: 99%

“…Also, the relaxation spectra of the suspensions were calculated by using experimental oscillatory shear data using the linear regression method. 20 For the first time, the steady shear viscosity of such suspensions were predicted by using the relaxation spectra.…”

Section: Introductionmentioning

confidence: 99%

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Viscoelastic properties of suspensions with weakly interacting particles

Bayram

Yilmazer

Orbey

1998

J. Appl. Polym. Sci.

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ABSTRACT:Rheological characterization of a model suspension containing hydroxylterminated polybutadiene and glass beads with filler concentration up to 30% by volume was performed by using a Haake parallel disk rheometer. The rheological tests conducted were the measurement of the storage modulus, GЈ, loss modulus, GЉ, and complex viscosity, *, as functions of the frequency and the steady shear viscosity as a function of the shear rate. The linear viscoelastic region was determined to extend up to 50% strain by measuring GЈ, GЉ, and * as functions of strain amplitude. By using multiple gap separations between the disks, it was found that the suspension did not exhibit slip at the walls of the rheometer. GЈ and GЉ were used to determine the relaxation times distribution, G i ( i , л) as functions of the relaxation time, i , and the filler content, л. The relaxation moduli, G i ( i , л), decreased with the relaxation time, but increased with the filler content. The Cox-Merz rule was also observed to be valid for these suspensions.

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“…The least-squares principle was applied to determine the values of G i . 20 The following sum in eq. (12) was calculated:…”

Section: Relaxation Times Distributionmentioning

confidence: 99%

Section: Relaxation Times Distributionmentioning

confidence: 99%

See 1 more Smart Citation

Viscoelastic properties of suspensions with weakly interacting particles

Bayram

Yilmazer

Orbey

1998

J. Appl. Polym. Sci.

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“…The extraction of h(τ) from G * (ω) is a celebrated inverse problem, with its own chequered past [18,[237][238][239][240][241][242][243][244][245][246][247][248][249][250][251][252][253][254].…”

Section: Linear Polymersmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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The extreme sensitivity of rheology to the microstructure of polymer melts has prompted the development of "analytical rheology," which seeks inferring the structure and composition of an unknown sample based on rheological measurements. Typically, this involves the inversion of a model, which may be mathematical, computational, or completely empirical. Despite the imperfect state of existing models, analytical rheology remains a practically useful enterprise. I review its successes and failures in inferring the molecular weight distribution of linear polymers and the branching content in branched polymers.

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“…In this study, the linear least squares method 29 was used in order to obtain the relaxation time and the relaxation strength. N sets of model parameters, (G i , i ) were determined by using the experimental sets of data [GЈ(w j ), GЉ(w j )] with eqs.…”

Section: Relaxation Times Distributionmentioning

confidence: 99%

Viscoelastic characteristics of chain extended/branched and linear polyethylene terephthalate resins

Yilmazer

Xanthos

Bayram

et al. 2000

J. Appl. Polym. Sci.

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Two chemically modified chain extended/branched polyethylene terephthalate (PET) resins and one unmodified resin, considered to be linear, were characterized in terms of their melt flow, die swell, and viscoelastic properties. The three resins had reportedly similar nominal intrinsic viscosities but exhibited different viscoelastic behavior. The modified resins had lower melt flow index, higher die swell, higher complex viscosity and higher storage modulus than the unmodified one. The Cole-Cole plots of the resins were independent of temperature, and the data for modified resins formed a group that lay below the data group for the unmodified PET. The distribution of relaxation times was determined. The modified resins had higher relaxation strength, G i , especially at high relaxation times, i . The mean relaxation times of the chain extended/branched resins were approximately an order of magnitude higher than that of the unmodified resin, implying pronounced elastic character. The modified resins had better foaming characteristics in extrusion foam processing than the unmodified one owing to their elastic nature.

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Determination of the relaxation spectrum from oscillatory shear data

Cited by 92 publications

References 0 publications

Viscoelastic properties of suspensions with weakly interacting particles

Viscoelastic properties of suspensions with weakly interacting particles

Analytical Rheology of Polymer Melts: State of the Art

Viscoelastic characteristics of chain extended/branched and linear polyethylene terephthalate resins

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