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Authors
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Naziri, A.A. ; Ehsani, M. ; Khonakdar, H. A. ; Hemmati, F. ; Jafari, S.H.
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Title
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Spherical nanoparticle effects on the lower critical solution temperature phase behavior of poly(epsilon-caprolactone)/poly(styrene-co-acrylonitrile) blends: Separation of thermodynamic aspects from kinetics
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Date
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04.11.2019
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Number
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57623
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Abstract
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The effects of spherical nanosilica particles on the lower critical solution temperature (LCST) phase diagram of poly(e–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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Publisher
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Journal of Applied Polymer Science
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Wikidata
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Citation
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Journal of Applied Polymer Science 137 (2019) 48679
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DOI
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https://doi.org/10.1002/APP.48679
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Tags
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