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 gamma crystalline form content is observed as a function of draw ratio, in parallel with an increased content of alpha crystalline phase. The gamma 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.