CARBONIZATION OF CRYSTALLINE POLYIMIDE PA RTICLES

New carbon particles were prepared from highly crystalline polyimide o nes treated at above 600 degrees C. Such particles were obtained by he ating polyamic acid solution as the result of thermal imidization of p olyamic acids in N-methyl-2-pyrrolidone. The polyimide particles start ed to thermally decompose from about 500 degrees C and almost finished being carbonized until 1000 degrees C in a yield of 50%. The morpholo gies of obtained carbon particles were unique like a whisker or coral which had the particle size from 1 mu m to 5 mu m, judging from the ob servation of SEM, and such particles hardly changed at all from the mo rphology of precursor in spite of extreme decomposing and carbonizing processes. By the treatment at 2800 degrees C, carbon particles from p oly(p-phenylene pyromellitimide) were found to be almost graphitized. These had the interlayer spacing d(002) of 3.39 Angstrom and crystalli te thickness of 250 Angstrom. It was observed by TEM that the structur e of particles like whiskers was made up by stacking of graphite layer s, and those layers were turned and closed in a loop at the end of eac h particle.