高强高模PET纤维拉伸过程超分子结构形成机理

用红外显微镜技术直接对单根聚对苯二甲酸乙二酯(PET)高强高模低缩纤维进行非破坏性光谱测量,同时进行广角X-射线衍射(WAXD)分析。主要研究了1100～750 cm - 1范围的红外光谱。通过谱带分离技术测定出PET纤维非晶区反式构象异构体含量。阐明了高强高模PET工业纤维在多级拉伸过程中各种分子构象的变化及形态结构的发展。结果表明:纤维的初始模量和断裂强力随非晶相反式构象含量的提高而增加。由于在第二级拉伸结束和随后的热辊定型过程使拉伸过程中发展起来的非晶相反式构象部分松驰下降到21.7% ,从而限制了机械性能的进一步提高。而经局部加热拉伸定型的纤维展示出较高的非晶区反式构象含量(30.1% ),纤维的机械性能有较大提高

CONFORMATIONAL CHANGES AND MORPHOLOGICAL DEVELOPMENT OF HIGH PERFORMANCE PET FIBERS DURING MULTI-STAGE STRECTCHING MEASURED

The FT IR microscopy has been used to obtain infrared spectra of each stage stretched poly (ethylene terephthalate) (PET) fiber samples during multi stage drawing. The trans and gauche content have been estimated from the absorbances of trans band at 846 cm -1 , the gauche band at 898 cm -1 , and the internal standard bands at 875 cm -1 . The trans content of crastalline and amorphous regions have been evaluated with the quench least square speak soluion treatment of the 1020 cm -1 band. The content percentage of the crystalline region trans, noncrystlline region trans and amorphous region gauche conformers were obtained by a combination of infrared data and X ray data. Our ihvestigation shows that the noncrystalline region trans content are related to the modulus and strength of PET fibers, and the decreasing substantially in noncrystalline region trans content during the heat setting following second stage drawing limited further increasing in mechanical properties of high modulus and high strengh PET fibers.