Influence of Hot Multistage Drawing on Structure and Mechanical Properties of Nylon 6 Multifilament Yarn

The effect of hot multistage drawing conditions on the structure and properties of nylon 6 fibers was investigated by varying second stage draw ratio. Total draw ratio was changed from 3.3 to 5.775 to clarify the structural changes in nylon 6 fiber at a broad range of draw ratio. The structural development of the fibers was studied with FTIR spectroscopy, differential scanning calorimetry (DSC), optical microscopy, and tensile testing. A continuous drop of the γ crystalline form content is observed as a function of draw ratio, in parallel with an increased content of α crystalline phase. The γ crystalline phase vanished completely at draw ratio of 4.62. Increasing draw ratio caused an increase in birefringence and no significant change occurred in crystallinity for the drawn nylon 6 fibers. Deformation behavior of drawn nylon 6 fibers has been explained in terms of applied thermal treatment and mechanical deformations which occurred in each step of multistage drawing.