Studies of Thermal Imidization Kinetics of Polyisoimide Based upon 4,4′-[1,4-Phenylenebis-(1-methyl ethylidene)] Bisaniline and 4,4′-Oxydiphthalic Anhydride in Solid State

Abstract

The curing kinetics of the polyisoimide (BIS-P/ODPA), based upon 4,4′-[1,4-phenylene-bis-(1- methyl ethylidene)] bisaniline (Bis-P) and 4,4′-oxydiphthalic anhydride (ODPA), was studied by differential scanning calorimetry (DSC). The glass transition temperatures of the partially imidized polyisoimides (Bis-P/ODPA) were measured by DSC as a function of fractional conversion. The thermal imidization of polyisoimides in the solid state showed a maximum degree of imidization that can be achieved at a given isothermal temperature probably due to the diffusion-controlled reaction characteristics near vitrification ( T g effect). Dynamic curing studies were performed at different heating rates of 1, 2, 5, 10, 15, 20, 25, 30°1. These data were analyzed for obtaining the activation energy and pre-exponetial value for the imidization reaction. The thermal imidization was well described by first-order kinetics with activation energy of 181-202 kJ mol−1 and the pre-exponential factor of 36-40 min−1.

Characterization of poly(amic acid)s and resulting polyimides bearing azobenzene moieties including investigations of thermal imidization kinetics and photoinduced anisotropy

“…To calculate the frequency factor, we assume that the imidization reaction is a first‐order reaction. A first‐order kinetic equation is almost exclusively used to treat imidization kinetics …”