Shish‐kebab structures of nylon‐6 obtained from quiescent solutions by application of self‐seeding

A study has been made of the morphology and structure of nylon‐6 crystals grown from diluted 1,4‐butanediol solution. Isothermal crystallization from homogeneous solution resulted in smooth ribbons or lath‐shaped crystals aggregated into sheaves. Shish‐kebab structures of nylon‐6 could be grown from the quiescent solution by self‐seeding techniques. Electron microscopic investigations and small‐angle x‐ray measurements showed that the molecules in the lath‐shaped backbones of the shish kebab are folded and oriented perpendicular to the long axis of the crystals. The polyamide laths have the α‐monoclinic crystal structure with the hydrogen bonds parallel to the long axis. It is suggested that due to the anisotropic type of bonding in the crystal lattice the crystals fragment laterally during the heating stage in the self‐seeding technique. Structural defects, e.g., twinning sites introduced during the dissolution and subsequent crystallization may cause the growth of shish‐kebab structures from quiescent solution.