Continuous polymer fractionation of poly(methyl vinyl ether) and a new Kuhn‐Mark‐Houwink relation

Petri, Hans‐Michael; Stammer, Andreas; Wolf, Bernhard

doi:10.1002/macp.1995.021960508

Cited by 16 publications

(19 citation statements)

References 12 publications

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“…Materials. Samples of PVME with a reasonably low polydispersity index M w / M n were obtained by continuous polymer fractionation (CPF) . The original material was the commercial Lutonal M40, from BASF.…”

Section: Methodsmentioning

confidence: 99%

“…from the homogeneous to the phase-separated regime. The system chosen, a mixture of polystyrene (PS) and poly(vinyl methyl ether) (PVME), is a lower critical solution temperature (LCST) blend that has been studied extensively in the past. − , Nevertheless, the above questions mainly arise from the previous works with PS/PVME. Moreover, it is a good system to study rheologically in a wide temperature range, since, as will be discussed in the next sections, the suitable choice of component molecular weights leads to cloud points in the range of 100 °C while in the entangled state.…”

Section: Introductionmentioning

confidence: 99%

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Rheology of a Lower Critical Solution Temperature Binary Polymer Blend in the Homogeneous, Phase-Separated, and Transitional Regimes

et al. 1996

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Small amplitude oscillatory shear rheology is employed in order to investigate the linear viscoelastic behavior of the lower critical solution temperature blend polystyrene/poly(vinyl methyl ether), PS/PVME, as a function of temperature and composition. At low temperatures, where the mixture is homogeneous, the dependence of the zero shear viscosity (η0) on concentration is measured and is well-described by means of a new mixing rule, based on surface fractions instead of volume fractions. Shift factors from time-temperature superposition (TTS) exhibit a Williams−Landel−Ferry (WLF) behavior. As the macrophase separation temperature is approached (the phase diagram being established by turbidity measurements), the blend exhibits a thermorheologically complex behavior. A failure of TTS is observed at low frequencies, both in the homogeneous pretransitional and in the two-phase regimes. Its origin is attributed to the enhanced concentration fluctuations, which exhibit a critical slowing down near the phase boundary in the homogeneous regime, and in the two-phase morphology inside the phase-separated regime. The anomalous pretransitional behavior can be quantified using a recent mean field theory, yielding the spinodal temperature. Furthermore, in the two-phase region an intermediate region of enhanced moduli at low frequencies is observed, followed by flow at even lower frequencies, which is attributed to the two-phase structure. The linear viscoelastic properties of the phase-separated blends are, to a first approximation, adequately described by a simple incompressible emulsion model considering a suspension of droplets of one coexisting phase in the matrix of the other phase.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rheology of a Lower Critical Solution Temperature Binary Polymer Blend in the Homogeneous, Phase-Separated, and Transitional Regimes

et al. 1996

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“…This can also be ensured by the transparent nature of the sample with a slight yellow color. 12 Graphite akes were obtained from Superior Graphite. Sulfuric acid (H 2 SO 4 , 98%), phosphoric acid (H 3 PO 4 , 85%), potassium permanganate (KMnO 4 , 99.9%), and hydrogen peroxide (H 2 O 2 , 30%), were purchased from Merck (Darmstadt, Germany).…”

Section: Materials and Sample Preparationmentioning

confidence: 99%

Reduced graphene oxide induced phase miscibility in polystyrene–poly(vinyl methyl ether) blends

et al. 2014

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“…PVME is prone to oxidative degradation and hence, adequate steps were taken to prevent this. 7,8 Commercial grades of atactic polystyrene (PS) with a weight average molecular weight (M w ) of 35 000 g mol À1 and with a polydispersity of 2.0 was obtained from Sigma Aldrich. Multiwall carbon nanotubes (MWNTs) (NC 7000) were obtained from Nanocyl (Belgium).…”

Section: Methodsmentioning

confidence: 99%

Non-equilibrium segmental dynamics driven by multiwall carbon nanotubes in PS/PVME blends

Xavier

Bose

2014

Phys. Chem. Chem. Phys.

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The present paper discusses the effect of multiwall carbon nanotubes (MWNTs) on the structural relaxation and the intermolecular cooperativity in dynamically asymmetric blends of PS/PVME (polystyrene/poly(vinyl methyl ether)). The temperature regime where chain connectivity effects dominate the thermodynamic concentration fluctuation (T/Tg > 0.75, Tg is the glass transition temperature of the blends) was studied using dielectric spectroscopy (DS). Interestingly, in the blends with MWNTs a bimodal distribution of relaxation was obtained in the loss modulus spectra. This plausibly is due to different environments experienced by the faster component (PVME) in the presence of MWNTs. The segmental dynamics of PVME was observed to be significantly slowed down in the presence of MWNTs and an Arrhenius-type behavior, weakly dependent on temperature, is observed at higher frequencies. This non-equilibrium dynamics of PVME is presumed to be originating from interphase regions near the surface of MWNTs. The length scale of the cooperative rearranging region (ξCRR) at Tg, assessed by calorimetric measurements, was observed to be higher in the case of blends with MWNTs. An enhanced molecular level miscibility driven by MWNTs in the blends corroborates with the larger ξCRR and comparatively more number of segments in CRR (in contrast to neat blends) around Tg. The configurational entropy and length scale of the cooperative volume was mapped as a function of temperature in the temperature regime, Tg < T < Tg + 60 K. The blends phase separated by spinodal decomposition which further led to an interconnected PVME network in PS. This further led to materials with very high electrical conductivity upon demixing.

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Continuous polymer fractionation of poly(methyl vinyl ether) and a new Kuhn‐Mark‐Houwink relation

Cited by 16 publications

References 12 publications

Rheology of a Lower Critical Solution Temperature Binary Polymer Blend in the Homogeneous, Phase-Separated, and Transitional Regimes

Rheology of a Lower Critical Solution Temperature Binary Polymer Blend in the Homogeneous, Phase-Separated, and Transitional Regimes

Reduced graphene oxide induced phase miscibility in polystyrene–poly(vinyl methyl ether) blends

Non-equilibrium segmental dynamics driven by multiwall carbon nanotubes in PS/PVME blends

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