CORRESPONDENCE OF LAMELLAR THICKNESS TO MELTING-POINT OF NYLON-6,6 SINGLE-CRYSTAL

The correspondence of lamellar thickness to the melting point of nylon-6,6 single crystal annealed in glycerol or without solvent was examined by hydrolysis in acids and by gel permeation chromatography. The annealed samples showed a stepwise increase in lamellar thickness, which corresponded to the crystal thickness calculated from the observed melting point. Two lamellar thickening processes were observed for samples annealed in glycerol at high temperatures, an incomplete thickening process by half the length of one monomer unit and a complete thickening process evaluated to be about one and a half times the thickness of the former. The crystal thickness formed by the latter process corresponds to the thickness (and melting point) of solution-grown crystal isothermally crystallized under the same conditions. The large long spacings which led to approximately doubling or quadrupling of the lowest (main) crystal thickness were frequently observed. The scale of lamellar thickness against melting point was assessed and it was concluded that the scale is probably reliable.