Crystal structure and morphology of polyacrylonitrile in dilute solution

It has been possible to crystallize polyacrylonitrile from dilute solutions of propylene carbonate in the form of thin platelets. These platelets are ellipsoidal in shape and approximately 100 A. thick. Electron diffraction shows that the platelets are essential single crystals and the polymer axis is nearly perpendicular to the plane of the platelet. Five separate reflections were measured and indexed. The spacings calculated for these reflections agree with previously reported x‐ray values obtained from drawn fiber. However, the present electron diffraction data require a different indexing of the reflections resulting in revised unit cell dimensions.