Relation between carbonization behavior of polycarbodiimide films and stabilization conditions Original Research Article

In the process of produce carbon materials by pyrolyzing polycarbodiimide (PCDI), the starting PCDI is preliminarily stabilized by a low temperature treatment in an oxidative atmosphere. In this study, the relation between the carbonization behavior of PCDI films and the stabilization conditions was investigated with the aim of optimizing stabilization conditions. The extent of stabilization was evaluated from the changes in tensile modulus during stabilization and density. A two stage stabilization was proposed to obtain sufficient thermal stability without causing fusion of the films. From the viewpoint of minimizing weight loss and volume reduction and maintaining the shape of the starting material during carbonization, PCDI films required a stabilization giving densities in the region from ca 1.22 to 1.26 g cm−3. During carbonization, a large weight loss took place at ca 480°C, and the decomposition at this temperature favored the crystallite growth at higher carbonization temperatures. Thus, with increasing density of the stabilized film beyond 1.26 g cm−3, more intensive decomposition took place, and the crystallite size and the density of the carbonized films increased although the weight loss increased.