Anisotropic mechanical properties of drawn nylon 6. I. The α phase

Abstract

Cold-drawn uniplanar-axially oriented sheets of nylon 6 have been annealed at 195°C, hot-rolled at 130°C, and then chemically treated with phenol to form the α crystalline phase. The morphology is parallel-lamellar, with the molecular chains at right angles to the lamellar plane. The long period is 96.7 ± 0.7 Å. The extensional compliances S₃₃ (parallel to the draw direction) and S₁₁ (the transverse direction in the sheet) and the shear compliances S₄₄, S₅₅, and S₆₆ have been measured at 20.0 ± 0.3°C by dead-loading creep and torsional methods, in two relative humidity ranges, 0–10% and 61–69% RH. Dependence upon time (creep), strain, and humidity have also been determined. The extensional compliances show the cross-over of S₃₃ above S₁₁ when the α_a transition or T_g is reduced to below room temperature by increasing the relative humidity from zero to 65%. The results are explained by using Takayanagi models for the extensional compliances and interlamellar shear or crystallite shear for the shear compliances.