The behavior of thin supported and non-supported films has been shown to be distinct from the bulk polymer.
Separately, high surface area fillers such as montomorillonite layered silicates (MLS) result in improved properties. In this
study, we investigate thin films of polyethylene terephthalate (PET) with MLS. The thermal expansivity and glass transition
temperature (Tg) were determined using ellipsometry. The results show that with increasing MLS concentration, the
glass transition drops for the thin and thick film plateaus. For intermediate thicknesses, a modest influence of the MLS
polymer interface on the characteristic length is found. The liquid layer thickness decreases with increased MLS presence.