Evolution of concentration fluctuation during phase separation in polymer blends with viscoelastic asymmetry

Xu, Yafang; Huang, Chongwen; Yu, Wei; Zhou, Chixing

doi:10.1016/j.polymer.2015.04.052

Cited by 16 publications

(14 citation statements)

References 52 publications

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“…The measurement of linear viscoelastic responses is an efficient tool for the study of the phase behavior of polymer mixtures due to the high sensitivity of the rheological properties to the concentration fluctuation and phase‐separated morphologies . Thus, to determine the phase‐transition points of PCL/SAN blends and PCL/SAN/Si nanocomposites, isochronal dynamic temperature sweeps at different cooling rates including 0.5, 1.5, and 3 K min −1 were employed by cooling down the heterogeneous samples from the phase‐separated to the well‐mixed region of the phase diagram.…”

Section: Resultsmentioning

confidence: 99%

“…The arrested matrix molecular motions in the presence of nanosilica particles is verified by comparing the chain repetition time ( t r ). t r is determined from the reciprocal frequency ( ω r ), wherein G′ = G ′′, by using the equation of t r = 1/ ω r . Moreover, the variable Δξ can be used to quantitatively determine the variation of the PCL/SAN viscoelastic asymmetry by adding the nanofiller . This variable is defined based on the dynamic asymmetry variable, ξ , of PCL and SAN as the fast and slow components of the mixture as follows:

normalΔ ξ = \frac{ξ_{blend} - ξ_{nano}}{ξ_{blend}} \times 100

where

ξ = \frac{true}{t_{italicrs}}

.…”

Section: Resultsmentioning

confidence: 99%

“…The refractive indices of polymers, film transparency, and thickness are the most important parameters in SALS and optical microscopy measurements that can affect the validity of the results . Following the linear viscoelastic responses over the phase transition is one of the well‐established strategies to study the phase behavior of polymer mixtures, which is less affected by the film transparency and thickness . Because of the high sensitivity to the chain repetition time, diffusion, and interfacial viscoelasticity, the rheological measurements can correlate the linear viscoelastic responses of polymer mixtures with subtle structural changes during phase separation process and detect the phase transition in rather early stages .…”

Section: Introductionmentioning

confidence: 99%

“…Most of these researches employed the rheological measurements for evaluating the phase behavior changes of the polymer mixtures . However, the measured viscoelastic responses over the phase‐transition boundary are the complex combinations of several controlling factors including thermodynamics, kinetics, and viscoelasticity …”

Section: Introductionmentioning

confidence: 99%

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Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends: Separation of thermodynamic aspects from kinetics

Naziri

Ehsani

Khonakdar

et al. 2019

J of Applied Polymer Sci

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The effects of spherical nanosilica particles on the lower critical solution temperature (LCST) phase diagram of poly(ε‐caprolactone) (PCL)/poly(styrene‐co‐acrylonitrile) (SAN) blends are investigated by using isochronal dynamic temperature sweep tests at different cooling rates. A stronger dependency of the rheologically determined phase‐transition points on the cooling rate is observed in the presence of nanoparticles, which results from the large contribution of entropic surface tension of chains in the Gibbs free energy of mixing and much slower rate of PCL/SAN phase dissolution. By alleviating the effects of kinetic factors, it is found that the drop in the LCST‐type phase boundary of PCL/SAN blends by adding nanofiller is more apparent than real. However, the closest LCST phase diagram to the real steady‐state thermodynamic diagram shows an unexpected shift to lower temperatures by adding nanosilica. The migration of nanosilica particles to the SAN domains especially at lower cooling rates in the dynamic measurements is the most likely explanation of these observations. The findings that prove the profound impact of kinetic factors in dynamic temperature measurements are reached in a hybrid system, wherein the SAN chains are preferentially absorbed on the surface of a nanofiller having very small primary particle size. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48679.

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Section: Resultsmentioning

confidence: 99%

normalΔ ξ = \frac{ξ_{blend} - ξ_{nano}}{ξ_{blend}} \times 100

where

ξ = \frac{true}{t_{italicrs}}

.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends: Separation of thermodynamic aspects from kinetics

Naziri

Ehsani

Khonakdar

et al. 2019

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Jinnai et al proposed that the time evolution of amplitude of concentration fluctuation could be determined by small‐angle neutron scattering (SANS) based on the random‐phase approximation. Yu et al also quantified the evolution of amplitude of concentration fluctuation using rheology by decoupling the modulus contributions from the components and interface. Here, with the incorporation of nanoparticles into polymer blends, the transmittance and modulus induced by nanoparticles would complicate the quantification of amplitude of concentration fluctuation.…”

Section: Introductionmentioning

confidence: 99%

Evolution of concentration fluctuation during phase separation of polystyrene/poly(vinyl methyl ether) blend in the presence of nanosilica

Chen

Zuo

Yang

et al. 2017

J. Polym. Sci. Part B: Polym. Phys.

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The influence of nanosilica on the concentration fluctuation of polystyrene/poly (vinyl methyl ether) (PS/PVME) mixtures was investigated during phase separation. The amplitude of concentration fluctuation was quantified by dielectric spectrums based on the idea of Lodge-Mcleish model and the linearized Cahn-Hilliard theory could describe the amplitude evolution of concentration fluctuation at the early stage of phase separation. Hydrophilic nanosilica A200 dispersed in PVME-rich phase behaved an obvious inhibition effect on the concentration fluctuation of blend matrix, while hydrophobic nanosilica R974 dispersed in PS-rich phase had little effect on the concentration fluctuation. The kinetics and amplitude evolution of concentration fluctuation during phase separation for PS/PVME/A200 nanocomposites were remarkably restrained due to the surface adsorption of PVME on A200. As the segmental dynamics of PVME and PS in homogeneous matrix was hardly influenced by A200 and R974, the enhanced miscibility and the significantly constrained flow relaxation of PVME chains might contribute to the retarded concentration fluctuation of PS/PVME/A200 nanocomposites. While the weak interaction between R974 and components of blend matrix and little effect of R974 on the molecular dynamics of PS chains may result in the weak retardation of concentration fluctuation for blend matrix.

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Determination of phase diagram of polyolefin blend nanocomposites by rheological approach: Influence of rheological method and nanoparticles on shifting the phase transition boundary

Hosseiny,

Jafari,

Hemmati

et al. 2024

J of Applied Polymer Sci

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In this research, by using different rheometric methods, the temperatures of phase transition for upper critical solution temperature phase diagram of polyethylene (PE) and poly(ethylene‐co‐vinyl acetate) (EVA) blends and filled systems with organically‐modified nanoclay (ONC) were measured. Since the PE/EVA‐based mixtures are widely applied in the film and foam industries, the evaluation of the phase behavior of these mixtures is of great importance. Microscopic observations show that ONC nanoparticles have a compatibilization role on the biphasic microstructure of PE/EVA. ONC nanoparticles have a remarkable impact on the viscoelastic properties of the EVA phase, leading to a reduction in the asymmetry of the viscoelastic properties of the two polymeric phases. The findings of this work focused on the isochronal dynamic temperature sweep tests on the well‐mixed and phase‐separated nanofiller‐filled systems with different cooling/heating rates indicated that these series of experiments did not have the necessary efficiency to determine the phase separation boundary and spinodal temperatures in thermodynamically equilibrium conditions. By using Han plot and dynamic temperature sweep tests at the minimum possible heating rate, 0.25 K/min, it was proved that by adding nanoparticles to PE/EVA blends, the area of well‐mixed region of the phase diagram did not show a significant increment. The pinning effects of nanoparticles on the polymeric chains and correspondingly, the reduction of molecular dynamics mainly affect the phase separation phenomenon.

show abstract

Evolution of concentration fluctuation during phase separation in polymer blends with viscoelastic asymmetry

Cited by 16 publications

References 52 publications

Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends: Separation of thermodynamic aspects from kinetics

Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends: Separation of thermodynamic aspects from kinetics

Evolution of concentration fluctuation during phase separation of polystyrene/poly(vinyl methyl ether) blend in the presence of nanosilica

Determination of phase diagram of polyolefin blend nanocomposites by rheological approach: Influence of rheological method and nanoparticles on shifting the phase transition boundary

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