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

1.我们试图建立一种适合高速纺丝纤维（hss纤维）的结构分析技术，通过该技术可以直接阐明PET， PEN[聚萘二甲酸乙烯酯]和PET/PEN共混物的纤维某些性能的来源。(1) PEN碱蚀hss纤维（纺丝速度大于等于4 km/mm）具有纤维织构和由层叠片状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，并用透射电镜对其进行了表征。PEN的电子衍射（ED）表现为高度单轴取向，与PEN hss纤维的广角x射线衍射（XD）一致。将这种PEN薄膜作为hss纤维的模型试样。PET的ED值与hss纤维的XD值吻合较好。(3)对于PET/PEN共混物的单轴取向薄膜，ED模式由两种均聚物晶体的反射组成，也表现出高度的单轴取向。通过暗场成像，发现PEN可以在单轴取向薄膜中形成片层状晶体，并且这种倾向比在PET中更为明显。随着PET含量的增加，形貌由PET型转变为PEN型，PET抑制了PEN片层的形成，相反，PET抑制了PET的结晶。制备了PBT[聚对苯二甲酸丁二酯]取向薄膜，并用透射电镜对其进行了表征。虽然它们的ED模式仅由α-型的弧形反射组成，因此显示出较不发达的单轴取向，但PBT比PEN更清晰地观察到堆叠层状结构。结果表明，每个结构中堆叠的薄片形成了一个羊肉串结构。基于本文所使用的所有聚酯取向薄膜的结果，我们提出了一种“先进”的羊肉串结构模型。

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.