Characteristic length of glass transition from calorimetry in different confinements

The characteristic length xi(alpha) from calorimetry describes the size of subsystems which are statistically independent from environment with respec t to Fourier components of entropy fluctuation relevant for the or relaxati on [1]. This paper is a review of our results in confined geomeuies. The le ngths are determined for three different geometric situations, 1. Self-orga nized amorphous mobile layers between crystalline layers in semicrystalline polyethylene terephthalate PET. Parameter: layer thickness [2]. 2. Tempera ture modulated DSC (TMDSC) of the glass former benzoin isobutyl ether (BIBE ) in coated pores of different glasses. Structural effects can be separated from the glass transition. Parameter: pore size from 2.0 to 7.5 nm [3]. Th e characteristic lengths in confined geometries are smaller than in bulk an d decrease systematically for decreasing confinement sizes. 3. Determinatio n of the thickness of immobilized layers on spherical fillers in SBR rubber s. This experiment is twofold complementary to the usual experiment in pore s: particles instead of pores, and immobilization instead of active respons e. Parameters: filler size and content, related by a scaling method [4].