The blend rheology of some linear and branched polymers

Groves, D. J.; McLeish, Tom; Ward, N. J.; Johnson, A. F.

doi:10.1016/s0032-3861(97)10021-0

Cited by 10 publications

(14 citation statements)

References 7 publications

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“…and cos sin (34) Applying boundary conditions (28) and (29) Mode set C: These comprise two degenerate sets of modes in which the backbone and the arms of one end do not move, while the arms at the other end stretch antisymmetrically from the branchpoint, which itself does not move. Hence one set of modes are given by: (36) and sin…”

Section: Mode Set Amentioning

confidence: 99%

“…When changing the molecular structure of the probe (slower) polymer, CR may have a different influence on non-reptative terminal relaxation. However, other than experimental studies involving star and linear mixtures, there are only a few other studies of binary mixtures of well-characterized architecturally complex polymers [33][34][35] . Yet, such blends are encountered in all technological applications.…”

Section: Introductionmentioning

confidence: 99%

“…When changing the molecular structure of the probe (slower) polymer, CR may have a different influence on nonreptative terminal relaxation. However, other than experimental studies involving star and linear mixtures, there are only a few other studies of binary mixtures of well-characterized architecturally complex polymers. − Yet, such blends are encountered in all technological applications. In this work, we wish to further understand the relaxation of such complex polymer blends by studying the viscoelastic response of a model H-polymer blended into linear chain matrices of different molar masses.…”

Section: Introductionmentioning

confidence: 99%

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Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

et al. 2019

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We investigate the influence of the environment on the relaxation dynamics of well-defined Hpolymers diluted in a matrix of linear chains. The molar mass of the linear chain matrix is systematically varied and the relaxation dynamics of the H-polymer is probed by means of linear viscoelastic measurements, with the aim to understand its altered motion in the different blends, compared to its pure melt state. Our results indicate that short unentangled linear chains accelerate the relaxation of both the branches and the backbone of the H-polymers by acting as an effective solvent.On the other hand, the relaxation of the H-polymer in an entangled matrix is slowed-down, with the degree of retardation depending on the entanglements number of the linear chains. We show that this retardation can be quantified by considering that the H-polymers are moving in a dilated tube at the rhythm of the motion of the linear matrix.

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Section: Mode Set Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

et al. 2019

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“…Simple mixing laws for the modulus such as the relation in (1), where ν is an arbitrary number, 12 are not expected to work in general because they assume time scales are not mutually affected by blending. This may be disguised in some cases by preexisting polydispersity on the blend fractions 13 but should find monodisperse blends a harder test. Indeed, we will find that no mixing law that assumes the relaxation times of the two species to be constant can work, because those relaxation times are observed to vary dramatically as blend fractions are varied.…”

Section: Introductionmentioning

confidence: 99%

Rheology and Tube Model Theory of Bimodal Blends of Star Polymer Melts

et al. 1998

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Experiments on solution-cast blends of two anionically synthesized monodisperse star-shaped polyisoprene molecules of widely different molecular weight exhibit a very rich rheological behavior. The time-dependent moduli are exponentially dependent on the relative volume fraction of each species. This work models these new features by extending existing theories for monodisperse melt of star polymers to the blend of two monodisperse star polymers with different molecular weight, keeping the same chemistry. The theory is based on the tube model with constraint release for star polymers in both an approximate and then a more exact level. The latter, with its treatment of nonactivated as well as activated breathing modes, is able to account quantitatively for the huge range of blend rheologies. With no extra parameters, it is able to account qualitatively for relaxation times and entire relaxation functions that vary over many orders of magnitude on blending.

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“…Polymer blending is one of the most versatile methods for modifying the properties of materials. Blends containing branched polymers are of particular interest − as they present possibilities for tailoring both bulk and surface physical properties without large changes in the chemical nature of the material. Tailoring both bulk and surface properties of blends requires a knowledge of the bulk thermodynamics.…”

Section: Introductionmentioning

confidence: 99%

Effects of Branch Points and Chain Ends on the Thermodynamic Interaction Parameter in Binary Blends of Regularly Branched and Linear Polymers

Lee

Foster

2006

Macromolecules

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The architectural effects of branch points and chain ends on the bulk thermodynamic interaction parameter, χ eff , in binary blends of branched polymers with their linear analogues have been investigated using small-angle neutron scattering (SANS) and a series of well-defined, regularly branched polystyrenes with the same molecular weight and differing only in the number of branch points or chain ends. The value of χ eff increases as the number of branch points increases for constant number of chain ends or as the number of chain ends increases for constant number of branch points. A Gaussian field theory for an athermal blend predicts the general trend in bulk χ eff with the number of chain ends but does not capture the changes in χ eff with changes in the number of branch points. Differences in chemistry among the various branch points probably have to be included to quantitatively predict changes in χ eff for shorter branches. Qualitative variations in the size of the branched molecules in solution compare favorably with a Gaussian model for the branched chain's radius of gyration. The variation in the average statistical segment length with chain architecture was also determined from the SANS data.

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The blend rheology of some linear and branched polymers

Cited by 10 publications

References 7 publications

Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

Rheology and Tube Model Theory of Bimodal Blends of Star Polymer Melts

Effects of Branch Points and Chain Ends on the Thermodynamic Interaction Parameter in Binary Blends of Regularly Branched and Linear Polymers

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