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Broadband Dielectric Relaxation Spectroscopy in Polymer Nanocomposites
Author(s) -
Pissis Polycarpos,
Fragiadakis Daniel,
Kanapitsas Athanasios,
Delides Kostas
Publication year - 2008
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200850502
Subject(s) - materials science , nanocomposite , differential scanning calorimetry , glass transition , dielectric , polymer , nanoparticle , relaxation (psychology) , composite material , polymer nanocomposite , spectroscopy , epoxy , polymer chemistry , chemical engineering , nanotechnology , optoelectronics , thermodynamics , psychology , social psychology , physics , quantum mechanics , engineering
Summary: Dielectric spectroscopy in the frequency domain and thermally stimulated depolarization currents techniques, covering together a broad frequency range (10 −4 –10 9 Hz), were employed to investigate molecular dynamics in relation to structure and morphology in polymeric nanocomposites. Several systems were investigated, three of them with the same epoxy resin matrix and different inclusions (modified smectite clay, conducting carbon nanoparticles and diamond nanoparticles) and two with silica nanofiller (styrene‐butadiene rubber/silica and polyimide/silica nanocomposites). Special attention was paid to the investigation of segmental dynamics associated with the glass transition of the polymer matrix, in combination also with differential scanning calorimetry measurements. Effects of nanoparticles on local (secondary) relaxations and on the overall dielectric behavior were, however, also investigated. Several interesting results were obtained and discussed for each of the particular systems. Two opposite effects seem to be common to the nanocomposites studied and dominate their behavior: (1) immobilization/reduction of mobility of a fraction of the chains at the interface to the inorganic nanoparticles, due to chemical or physical bonds with the particles, and (2) loosened molecular packing of the chains, due to tethering and geometrical confinement, resulting in an increase of free volume and of molecular mobility.