Comparative study of mechanical and electrical relaxations in poly(etherimide). Part 2

Abstract

The curves describing the relaxation behaviour of poly(etherimide) at several frequencies shows in the dielectric lossÈtemperature plot c and b relax- ations centred at [95¡C and 100¡C, respectively, at 10 Hz. The glassÈrubber relaxation or a process appears at 225¡C at 10 Hz; at this temperature free charge conductivity and blocking electrode phenomena become dominant at fre- quencies below 10 Hz. The same three relaxations are observed by dynamic mechanical thermal analysis (DMS). The strength of the c and a relaxations can be estimated from the Ðtting of empirical relaxation functions, such as the FuossÈ Kirkwood and HavriliakÈNegami equations, to the dielectric data measured in the frequency domain. An electric model was used to separate the dipolar response from conductivity contributions in the glassÈrubber relaxation. Finally, the e†ect of water on the low-temperature relaxation has been demonstrated by dielectric and mechanical measurements.