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Dynamic Glass Transition of the Rigid Amorphous Fraction in Polyurethane-urea/SiO2 Nanocomposites

Abstract

We report molecular dynamics in the rigid amorphous fraction (RAF) of the polymer bound at the interfaces with nanoparticles in polymer nanocomposites and calculate the glass transition temperature, Tg, for this bound layer of polymer. We follow the ‘3-phase-model’ for semicrystalline polymers where the polymer matrix consists of the crystalline fraction (CF), the mobile amorphous fraction (MAF) and the RAF. While amorphous polymer bound by crystallites is completely rigid, neither contributing to the glass transition, nor displaying molecular dynamics, amorphous polymer bound at the interfaces with filler displays decelerated dynamics, as compared to bulk polymer. Reports in the literature suggest a discrepancy between Tg values obtained by Differential Scanning Calorimetry (DSC) and by Dielectric Relaxation Spectroccopy (DRS). As plausible explanation we suggest that DRS results in Tg values taking into account the bound polymer, whereas DSC does not. For this investigation we use semicrystalline Polyurethane-urea/SiO2 nanocomposites and employ, next to DSC and DRS, SEM and XRD for morphological characterization. It is our intention for DRS to provide a tool for investigating the RAF.

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Publication details

The article was received on 24 Feb 2017, accepted on 18 May 2017 and first published on 19 May 2017


Article type: Paper
DOI: 10.1039/C7SM00397H
Citation: Soft Matter, 2017, Accepted Manuscript
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    Dynamic Glass Transition of the Rigid Amorphous Fraction in Polyurethane-urea/SiO2 Nanocomposites

    S. Koutsoumpis, K. N. Raftopoulos, O. Oguz, C. Papadakis, Y. Z. Menceloglu and P. Pissis, Soft Matter, 2017, Accepted Manuscript , DOI: 10.1039/C7SM00397H

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