Stirring-induced crystallization of nylon 6

A study has been made of the morphology and structure of nylon 6 crystals grown from stirred 1, 2, 6-hexanetriol solution. Nylon 6 crystallized as filmy aggregates around a stirrer and as suspended crystals in solution. Filmy aggregates are composed of fibrous crystals with diameters of 10–20 nm and the suspended crystals can be either elongated lamellae or needlelike. Electron microscopic investigations and x-ray diffraction measurements showed that the molecules in the fibrous crystals are folded and oriented perpendicular to the fiber axis. The fibrous crystals have the α-monoclinic crystal structure with the hydrogen bonds parallel to the fiber axis. The direction of the hydrogen bonds in the fibrous crystals is almost parallel to the flow direction of the solution. The suspended crystals are also α-form and chain-folded. The thermal behavior of the fibrous crystals was very similar to that of well-drawn nylon 6 fibers.