The nylon-6 yarns with different draw ratios were prepared

and the effect of drawing on the structural

morphological and textural features of these obtained yarns

such as the crystalline forms

the melting behavior and mechanical properties

were investigated by wide-angle X-ray diffraction (WAXD)

Fourier transform infrared spectroscopy (FTIR)

differential scanning calorimetry (DSC)

sound velocimeter

scanning electron microscope (SEM) and multifunction yarn strength tester.The results demonstrated that with the increase of draw ratios

the crystallinity of nylon-6 yarns raised continuously along with the growth of -form and -form crystals

which were induced by segmental rearrangement of the amorphous area.The characteristic diffraction peaks of -form crystal appeared in the sample under the draw ratio of 3 times.These behaviors occurred in crystalline form also led to the enhancement of the melting temperature and the formation of the multiple melting peaks.Moreover

the axial orientation degree of molecular chains increased with increasing draw ratios

which facilitated to eliminate the residual stress and improve the defects on the surface of fibers.With the combination of all above factors

the mechanical properties of nylon-6 multifilament were enhanced to some degree.Particularly

the tensile strength and tensile modulus of the sample drawn by 3 times reached to 5.0 cN/dtex and 28.9 cN/dtex

respectively

which were the highest values among all samples.