Nylon single crystals

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Abstract
Several polyamides crystallize from dilute glycerin solution as single crystals and spherulites possessing a lamellar structure. The crystal of nylon 6 are rhombohedral and thicken by spiral growth of lamellae from screw dislocations. Electron diffraction patterns indicate that the molecules are folded within the lamellae, which are 50–100 A. thick. The single‐crystal electron diffraction spacings correspond to those of the high‐temperature crystalline modification as determined by x‐ray diffraction. The unit cell, however, does not show the hexagonal symmetry generally ascribed to the high‐temperature lattice. Spherulites of nylon 6 are composed of fragmented lamellae in which the molecules are folded and are in the low temperature crystalline lattice. Preparations of nylon 66 and 610 contain structures consisting of single‐crystal lamallae rolled or folded together. These structures also thicken by spiral growth of the lamallae from screw dislocations. The molecules are folded and are in the low‐temperature lattice, although there is some evidence of the high‐temperature modification with nylon 610.