Anisotropic mechanical properties of drawn nylon 6. II. The γ phase

Publisher Website
Google Scholar
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 iodine (KI3 aqueous solution) to form the γ crystalline phase (called γ I ). As with the α phase, the morphology is parallel-lamellar with the molecular chains at right angles to the lamellar plane. The long period is 98.2 ± 0.7 Å. The hydrogen bonds form layers in the crystallite (100) planes which are at about 60° to the sample sheet, whereas in a they formed layers in the (001) planes which lie in the sheet. The extensional compliances S33 (in 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 and humidity have also been determined. In contrast to the α form, the extensional compliances do not show a cross-over of S33 above S11 when the αa transition or Tg is reduced to near room temperature by increasing the relative humidity from zero to 65%. The results are interpreted by using Takayanagi models for the extensional compliances and interlamellar or crystallite shear for the shear compliances. The overall anisotropy is less in γI than in α. This is a consequence of the kink in the molecular chains in γI which reduces both the extensional modulus of the crystallites and the intracrystalline shear.

This publication has 96 references indexed in Scilit: