Linear viscoelastic behavior of some incompatible polymer blends in the melt. Interpretation of data with a model of emulsion of viscoelastic liquids

Graebling, Didier; Müller, René; Palierne, Jean-François

doi:10.1021/ma00054a011

Cited by 524 publications

(428 citation statements)

References 9 publications

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“…In the literature, one can find numerous references (Inoubli et al 2006;Shikata and Pearson 1994;van der Werff et al 1989;Graebling et al 1993;Watanabe et al 1996;VignauxNassiet et al 1998) on suspensions showing secondary relaxation processes which are similar to the one described in this paper. Watanabe et al (1997) discuss the frequency dependence of the storage and loss moduli G and G of spherical styrene-isoprene micelles randomly dispersed in a nonentangling homopolyisoprene matrix.…”

Section: Discussionsupporting

confidence: 71%

Strain-induced low-frequency relaxation in colloidal DGEBA/SiO2 suspensions

et al. 2014

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Diglycidyl ether of bisphenol A (DGEBA) is widely exploited as an epoxy resin in adhesives and coatings. In this paper, it is used as an oligomer matrix for silicafilled nanocomposites. Rheological measurements show that the pure matrix obeys power-law relaxation dynamics in the vicinity of the dynamic glass transition of this lowmolecular-weight glass former. In the filled systems, a lowfrequency relaxation appears additionally to the structural α-process of the matrix. Considering the nanocomposites as Newtonian hard-sphere suspensions at low angular frequencies (or high temperatures), the modified terminal regime behavior of the matrix can be linked to strain-induced perturbations of the isotropic filler distributions. While in the low-frequency regime hydrodynamic stresses relax instantaneously, the Brownian stress relaxation is viscoelastic and can be evidenced by dynamic rheological measurements. At higher angular frequencies, the α-process of the matrix superimposes on the Brownian stress relaxation. In particular, we were able to depict the low-frequency anomaly for concentrated, semi-dilute, and even for dilute suspensions.

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Section: Discussionsupporting

confidence: 71%

Strain-induced low-frequency relaxation in colloidal DGEBA/SiO2 suspensions

et al. 2014

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“…Next, the desired step-down in the shear rate is applied, whereafter the flow is stopped at different time intervals from the step-down to perform the dynamic tests that ultimately yield the average drop radii. Indeed, a small strain oscillatory flow does not affect the morphology (Graebling et al 1993(Graebling et al , 1994Gramespacher and Meissner 1992;Vinckier et al 1996). OM is performed in order to interpret some of the results and to check the actual drop size.…”

Section: Experimental Methodsmentioning

confidence: 99%

Study of morphological hysteresis in partially immiscible polymers

et al. 2008

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The morphology evolution of two systems of partially immiscible polymers, differing in miscibility, is investigated by means of rheological experiments and optical microscopy. For each system, two concentrations, 10% and 20%, are used. For immiscible systems, a hysteresis zone, defined by coalescence and breakup, exists where the average drop radius is not a unique function of the shear rate. We investigate whether the findings also apply to partially immiscible polymers. The average radii at different shear rates, measured with rheology, are compared to model predictions. The hysteresis zone, if present, is indeed affected by the polymeric system, the concentration and the flow history applied. Coalescence evolution is measured for three different step-downs in shear rate. For both 10% systems, the resulting average radii show a rather high scattering and do not match the theoretical predictions. For the 20% concentrations, the average experimental drop sizes seem independent of the magnitude of the step-down, at least during a certain period of time. Thereafter, it experiences a sudden, in the time scale of the experiments unbounded, increase in size that is more pronounced for the higher step-downs. Deviations of the experimental data from theoretical predictions are attributed to the partially immiscible character of the systems, yielding enhanced coalescence which, in turn, can induce confinement effects.

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“…The viscoelastic relaxation time τ D of droplets for small deformation is given by 24,25) For the retraction of isolated droplets, τ D can be determined by extrapolating φ → 0. 19) Experimental results show that plots of λ a versus (t − t s )/τ D make a single curve for the shape retraction of spheroidal droplets independently of r 0 and γ, 11) where t s is the time at which the shape of the droplets becomes spheroid, and λ a at t = t s is experimentally determined as λ a (t s ) = 1.49.…”

Section: Time Evolution Of the Interface Velocity Term σ Vxymentioning

confidence: 99%

Effects of Interface Velocity on the Stress Tensor in Immiscible Polymer Blends: Retraction of Spheroidal Droplets and Stress Relaxation

Okamoto

Takahashi

2008

J. Soc. Rheol., Jpn

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The total stress tensor for immiscible polymer blends is calculated based on the theoretical expression by Batchelor (1970), andMellema andWillemse (1983) in the last stage of the stress relaxation under large step shear strains. In this stage, the shape of droplets is spheroid and the retraction of isolated droplets is calculated according to the theory developed by . The calculated results are compared with experimental data for a polyisobutylene/ polydimethylsiloxane blend. Contribution of the motion of the interface (the interface velocity term) to the total stress tensor in the theoretical expression for the isolated droplets is 37 % − 50 %, which cannot be neglected compared with the contribution of the pressure difference beyond the interface (the Laplace pressure term). The summation of both terms agrees well with the experimental data at step strain γ = 1, in which effects inherent in multiple droplet systems are the smallest. The γ dependence of the reduced stress appearing in the experimental data, which cannot be predicted by the theoretical calculation for the isolated droplets, is qualitatively explained by considering droplet size distribution in the theoretical calculation.

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Linear viscoelastic behavior of some incompatible polymer blends in the melt. Interpretation of data with a model of emulsion of viscoelastic liquids

Cited by 524 publications

References 9 publications

Strain-induced low-frequency relaxation in colloidal DGEBA/SiO2 suspensions

Strain-induced low-frequency relaxation in colloidal DGEBA/SiO2 suspensions

Study of morphological hysteresis in partially immiscible polymers

Effects of Interface Velocity on the Stress Tensor in Immiscible Polymer Blends: Retraction of Spheroidal Droplets and Stress Relaxation

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