MOLECULAR MOBILITY IN PARASUBSTITUTED POLYARYLS .2. GLASS-TRANSITION PHENOMENA IN AMORPHOUS POLY(ARYL ETHER ETHER KETONE)

The dynamic mechanical behavior of amorphous poly(aryl ether ether ketone) has been investigated and analyzed in the frame of a model involving quasi punctual defects (QPD model). Accordingly, the molecular motions responsible for the glass transition are cooperative and hierarchically constrained through series correlated processes. The Kolhrausch exponent of the relaxation function is identified with a correlation parameter b and is explicitly related to the microstructural state through the QPD's concentration Cd. In the liquid state, i.e. above the glass temperature, T(g), b and Cd increase with temperature. In the glassy state, we infer that Cd as well as b decrease during structural relaxation (physical aging). Different methods are considered to yield information about the correlation parameter, and the difficulties associated with the extraction of reliable values from the experimental data are outlined. Thus, the influence of the sub-T(g) relaxation process and temperature-dependent distribution effects are discussed.