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Dielectric investigation of the molecular dynamics of blends (II): polymers with dissimilar molecular architecture (PS/TMPC blend)
Author(s) -
Mansour Ashraf A.,
Madbouly Samy A.
Publication year - 1995
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.1995.210370405
Subject(s) - polystyrene , polycarbonate , materials science , polymer , glass transition , relaxation (psychology) , dielectric , polymer blend , polymer chemistry , thermodynamics , chemical engineering , composite material , physics , copolymer , psychology , social psychology , optoelectronics , engineering
The molecular dynamics of polystyrene/tetramethyl polycarbonate (PS/TMPC) blends were investigated using dielectric spectroscopy in the frequency and temperature ranges 10 −2 −10 7 Hz and 50–220°C, respectively. Blends with different compositions, namely 12.5, 25, 50, 75 and 87.5 wt% PS/TMPC were found to be compatible over the entire composition range and showed one glass relaxation process corresponding with the transition observed by calorimetric measurements. It was found that neither the kinetics or the distribution of relaxation times of the local process observed in pure TMPC were affected by blending. This fact implies that the local environment of the segments is not changed upon blending. Furthermore, these blends showed that the blending of TMPC with weakly polar polystyrene does not cause any change in the dipolar interaction of the TMPC segments, so that the relaxation strength varies linearly with composition. It is concluded that the polymeric chains of the TMPC and PS are not mixed at a segmental level, but at a higher structural level lying somewhere between segmental and molecular. This conclusion is in good agreement with that obtained in the case of blends composed of polymers with similar molecular architecture.