CARBONIZATION OF POLYIMIDE FILMS - EFFECT OF COLD-DRAWING AND CHEMICAL-STRUCTURE

Polyimides of various chemical structures were prepared from pyromelli tic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), ox ydianiline (ODA), and p-phenylenediamine (PDA). The cold-drawn polyimi de films were prepared and carbonized. The electrical conductivity of the carbonized films enhanced linearly with the draw ratio. The effect of cold-drawing on the electrical conductivity is more remarkable wit h the rigid polyimides such as PMDA/PDA and BPDA/PDA than the flexible polyimides such as PMDA/ODA and BPDA/ODA. The tendency is well in acc ord with the effect of cold-drawing on the improvement of modulus of p olyimides. With the rigid polyimides, the higher alignment of polymer chain is supposed to be achieved by the cold-drawing. (C) 1994 John Wi ley & Sons, Inc.