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Glass transition and cooperative rearranging regions in amorphous thermoplastic nanocomposites
Author(s) -
Greco Antonio,
Gennaro Riccardo,
Rizzo Michele
Publication year - 2012
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4212
Subject(s) - glass transition , materials science , differential scanning calorimetry , nanocomposite , amorphous solid , montmorillonite , chemical engineering , cyclohexane , relaxation (psychology) , organoclay , polymer , composite material , polymer chemistry , organic chemistry , thermodynamics , chemistry , psychology , social psychology , engineering , physics
The aim of this work was to study the effect of nanofillers on the structural relaxation phenomena occurring in amorphous poly(ethylene‐terephthalate)/poly(cyclohexane‐dimethanol terephthalate) copolymer (PET/PCHDMT) nanocomposites in correspondence with the glass transition temperature. PET/PCHDMT nanocomposites were prepared by melt mixing with an organic modified montmorillonite at different processing temperatures. Differential scanning calorimetry analysis revealed that addition of the organic modifier alone causes a decrease of the glass transition temperature and an increase of the specific heat discontinuity. Nanocomposites showed a higher glass transition temperature and a lower specific heat discontinuity compared with samples obtained by adding organic modifier to PET/PCHDMT. Both effects were more relevant for samples processed at lower temperatures. Therefore, the glass transition temperature was studied by introducing the concept of fictive temperature and relaxation time. It was found that nanocomposites have a higher apparent activation energy and an increased size of cooperatively rearranging regions compared with neat PET/PCHDMT. Both effects are more relevant for nanocomposites processed at lower temperatures. All the discussed effects are explained by considering the enhanced confinement of PET/PCHDMT macromolecules, due to the presence of intercalated lamellae of organofiller. The efficiency of intercalation is increased by decreased processing temperature, which involves an increase of the nano‐confinement area of the polymer. Copyright © 2012 Society of Chemical Industry