Three-dimensional shape of polyethylene single crystals grown from dilute solutions and from the melt

Three-dimensional morphology of polyethylene single crystals grown from dilute solutions and from the melt has been examined by atomic force microscopy. The observation of single crystals clarifies the morphology of chair-type as well as hollow pyramidal type for solution crystallization. From the melt, only chair-type was obtained. It has been confirmed that the screw dislocations in the chair-type follow a selection rule of the handedness in a manner to relieve the distortion in the chair-type. The meaning of the selection is discussed in connection with the twisting correlation in the banded spherulites grown from the melt of non-chiral polymers, such as polyethylene.