Eur. Phys. J. E 8, 201-207 (2002)
DOI: 10.1140/epje/i2001-10087-5
Effects of entanglement concentration on
and local segmental motions
P. Bernazzani1, S.L. Simon1, D.J. Plazek2 and K.L. Ngai3
1 Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409-3121, USA
2 Department of Materials Science and Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
3 Naval Research Laboratory, Washington, DC 20375-5320, USA
sindee.simon@coe.ttu.edu
(Received 15 August 2001 and Received in final form 2 March 2002)
Abstract
The process of spin-coating to fabricate thin polymer films with
high molecular weight can produce samples with entanglement concentrations
that are far below the equilibrium value. It is not clear whether or not
such low entanglement concentrations are responsible for the depression of
the glass temperature in thin polymer films. In this work, we measure the
calorimetric glass temperature and viscoelastic response of polystyrenes
with molecular weights ranging from
to
g/mol, for both bulk material and for samples freeze-dried from dilute
solution. We conclude that the reduction of the glass temperature observed
in thin polymer films cannot be due to the reduced entanglement
concentration in the samples.
64.70.Pf - Glass transitions.
68.60.Bs - Mechanical and acoustical properties.
62.20.Hg - Creep.
65.20.+w - Thermal properties of liquids: heat capacity, thermal expansion, etc..
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002
