Price, Duncan M.; Method and Apparatus for Modulated-Temperature Thermomechanical Analysis. US Patent 6,007,240 December 28 (1999)
By employing a "modulated-temperature" heating program composed of a series of heat-isotherm stages, it is possible to separate the change in dimensions of an oriented material during heating into two contributions: a thermally "reversing" component which is due to linear thermal expansion and a "non-reversing" part arising from relaxation to the disordered state on heating above Tg. Some preliminary results for biaxially drawn poly(ethylene terephthalate) film are presented.