DOI: 10.1140/epje/i2002-10111-4
Effect of physical ageing in thin glassy polymer films
S. Kawana1 and R.A.L. Jones21 Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
2 Department of Physics and Astronomy, University of Sheffield, The Hicks Building, Hounsfield Road, Sheffield S3 7RH, United Kingdom
kawana@rc.m-kagaku.co.jp
(Received 28 October 2002 / Published online: 1 April 2003)
Abstract
We have studied the effect of physical ageing in thin supported glassy
polystyrene films by using ellipsometry to detect overshooting in the
expansivity-temperature curve upon heating of aged samples. Films with
thickness 10-200 nm have been aged at
and
(below
the bulk glass transition temperature). We observe clear relaxation peaks
in the expansivity-temperature curve for films thicker than 18 nm but not
for the 10 nm film. The intensity of the relaxation peak is inversely
proportional to the film thickness, while the temperatures characteristic
to the relaxation peak are almost independent of the film thickness.
These observations are successfully interpreted by the idea that the
surface layer of the order of 10 nm has liquid-like thermal properties.
64.70.Pf - Glass transitions.
68.60.-p - Physical properties of thin films, nonelectronic.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003
