Dissolution and crystallization temperatures of high polymers. II. New method of characterization of polyacrylonitrile

Polyacrylonitriles prepared under different conditions have similar infrared spectra, x‐ray diffraction patterns, and densities, but they show marked differences in dissolution and crystallization behavior. On the basis of the dissolution and crystallization behavior, a characterization method, sensitive enough to show a small difference in chain regularity in the polymer, yet independent of the physical state and previous history of the sample, has been developed. With this method, polyacrylonitriles with different chain regularities can be conveniently differentiated.