牵伸作用对尼龙6纤维晶型结构及力学性能的影响

Effects of Drawing on Crystalline Forms and Mechanical Properties of Nylon-6 Fiber

利用广角X射线衍射仪(WAXD)、傅里叶变换红外光谱仪(FTIR)、示差扫描量热仪(DSC)、声速取向测量仪、扫描电镜(SEM)以及纱线强伸度仪研究了不同牵伸倍数尼龙6复丝的晶型结构、熔融行为、取向度、表面形貌以及力学性能.结果表明,随着牵伸倍数的增加,伴随着γ晶型片晶的生长以及非晶区链段重排诱导α晶型的生成,尼龙6复丝的结晶度不断的提高,在牵伸倍数达到3倍时,样品中出现了α晶型的特征衍射峰,导致了其熔融温度的提高以及多重熔融峰的出现.同时,牵伸作用也增加了分子链沿纤维轴向的取向程度,消除了纤维表面的残余应力,改善了纤维的表面缺陷.在这些因素的共同作用下,尼龙6复丝的力学性能得到了一定程度的提高,当牵伸倍数为3倍时,拉伸强度与拉伸模量分别达到了5.0 c N/dtex和28.9 c N/dtex,与较低牵伸倍数相比较均有所提高.

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 γ-form and α-form crystals,which were induced by segmental rearrangement of the amorphous area.The characteristic diffraction peaks of α-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 to5.0 c N / dtex and 28.9 c N / dtex,respectively,which were the highest values among all samples.