Polyimide isothermal studies

A representative sample of many of the polyimide films that were produced were subjected to thermo-mechanical analysis (TMA), torsional braid analysis (TBA), thermal gravimetric analysis (TGA), infrared spectral analysis and weight loss on prolonged heating (e.g. isothermal studies), TABLE II. The softening temperature as measured by TMA and TBA are in general... 

Brace et al. [92] investigated polymer/water interactions using SAW devices coated with either polyimide or cellulose acetate butyrate (CAB). In this study thermodynamic parameters were evaluated from the absorption isotherms, and transient responses to step changes in concentration were monitored. The transient responses observed were not consistent with Fickian diffusion, but could be described using a generalized relaxation equation containing two additive terms. Results under various conditions indicated that relaxation in the polymer system is much slower than diffusion of water. 

A dynamic method for acquiring and treating infrared spectroscopic data from the imidization of a number of polyimide systems is presented. In situ FT-IR analysis of polymer reactions is preferred when doing comparitive studies on a number of polymer systems. For systems where these reactions occur at relatively high temperatures, it is often difficult to obtain good isothermal data for determining kinetic parameters. Kinetic data for several polyimide systems are shown and compared. 

Table 5.3 Polyimide stability using isothermal ageing weight loss studies ...

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