【摘要】 以偶偶尼龙-6 18为例,通过示差扫描量热分析(DSC)、广角X射线衍射(WAXD)与傅里叶变换红外光谱(FTIR)等方法研究了其B rill转变的过程,探索了脂肪族聚酰胺的晶型转变的本质.X射线衍射结果表明,随着温度的升高,尼龙-6 18由三斜晶系转变为假六方晶型,同时其DSC曲线上出现一个较宽的吸热峰.红外光谱结果表明,在其晶型转变过程中,晶体内氢键强度逐渐减弱,与酰胺键相连的C—C和C—N键发生扭曲.酰胺基团之间的亚甲基链段的振动逐渐增强,部分亚甲基单元由反式构象变成旁式构象,最后整齐排列的亚甲基链段逐渐变得无序化.更多还原

【Abstract】 The Brill transition of even-even nylon-6 18 was investigated by using differential scanning calorimetry（DSC）,temperature-dependent wide angle X-ray diffraction（WAXD） and Fourier transform infrared（（FTIR））.The X-ray diffraction results indicate that the melt-crystallized sample of nylon-6 18 transforms from the triclinic unit cell to the pseudo-hexagonal phase in the temperature range of 120—180 ℃.In this range,the thermograph of nylon-6 18 presents a broad endothermal peak.From the FTIR spectra,it can be found that,during the transition process of nylon-6 18,the intensity of the intrasheet hydrogen bonds becomes weak.At the same time,the CH₂-amide bonds twist and the all-trans conformation of methylene sequences is disordered by inserting the gauche conformation.The CH₂ segments are in a mobile state because of the enhanced stretching and twisting vibrations of C-CO and C-N bonds.更多还原