Analysis of internal fine structures of high-speed-spun fibers of PET/PEN blends

1.我们试图建立一种适用于高速纺纤维（HSS-fibers）的结构分析技术，通过该技术可以直观地解释PET、PEN [聚萘二甲酸乙二醇酯]和PET/PEN共混物纤维某些性能的起源。（1）PEN的碱蚀HSS纤维（以4km/mm或更大的速度纺制）具有原纤结构和由层叠片层结构组成的精细网络结构。（2）采用剪切应变法制备了PET和PEN的单轴取向薄膜，并对薄膜进行了TEM观察。PEN的电子衍射（艾德）显示出高度单轴取向，并且与PEN HSS纤维的广角X射线衍射（XD）一致。这种PEN薄膜被认为是HSS纤维的模型样品。PET的艾德能谱与PET HSS纤维的X射线衍射能谱吻合较好。(3)As对于PET/PEN共混物的单轴取向薄膜，艾德图案由来自两种均聚物晶体的反射组成，并且还显示出高度单轴取向。通过暗场成像发现，PEN在单轴取向薄膜中可以形成层状晶体，并且这种趋势比PET中更明显。随着PET含量的增加，薄膜的形貌由PET型向PEN型转变，PET抑制了PEN层状结构的形成，而PEN则抑制了PET的结晶。2.制备了PBT [poly（butylene terephthalate）]取向薄膜，并用TEM对其进行了表征。尽管它们的艾德衍射图由仅归因于α晶型的弧形反射组成，因此显示出较不发达的单轴取向，但在PBT中观察到的堆叠片层结构比PEN中更清楚。可以得出结论，在每个结构中的堆叠层形成shish-kebab结构。基于从这里使用的所有取向的聚酯薄膜获得的结果，我们提出了一个“先进”的shish-kebab结构模型。

1.We tried to establish a suitable technique of structural analysis for the high-speed-spun fibers (HSS-fibers), with which the origin of some properties of the fibers can be straightfowardly elucidated for PET, PEN [poly(ethylene naphthalate)] and PET/PEN blends. (1)Fibrillar texture and a fine network structure consisting of stacked-lamella-like structures were recognized in the alkaline-etched HSS-fibers (spun at 4 km/mm or greater) of PEN. (2)Uniaxially oriented thin films of PET and PEN were prepared by applying shear-strain to the melt, and were examined by TEM. Electron diffraction (ED) of PEN showed a highly uniaxial orientation and was consistent with wide-angle x-ray diffraction (XD) of PEN HSS-fibers. Such thin films of PEN were regarded as a model specimen for the HSS-fibers. ED of PET is in good agreement with XD of PET HSS-fibers. (3)As for uniaxially oriented thin films of PET/PEN blends, ED patterns consisted of the reflections from both homopolymer crystals and also showed a highly uniaxial orientation. By dark-field imaging, it was recognized that PEN can form lamellar crystals in uniaxially oriented thin films and this tendency is more remarked than in PET. Morphology was changed from a PET-type to a PEN-type with increasing PET content, formation of PEN lamellae was depressed by PET, and to the contrary, crystallization of PET was suppressed by PEN.2.Oriented thin films of PBT [poly(butylene terephthalate)] were prepared and examined by TEM. Although their ED patterns consisted of the arc-shaped reflections attributed only to the α-form and accordingly showed a less-developed uniaxial orientation, stacked-lamellar structures were more clearly observed in PBT than in PEN. It was concluded that the stacked lamellae in each of the structures form a shish-kebab structure. Based on the results obtained from all the oriented thin films of polyesters used here, we proposed an "advanced" model of shish-kebab structure.