New insights into orientation distribution of high strength polyacrylonitrile-based carbon fibers with skin-core structure
| Autor: | Jian Xu, Ruigang Liu, Lianlong He, Zhen Fan, Yongxin Cheng, Xinshuang Guo, Zhihai Feng |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
media_common.quotation_subject Polyacrylonitrile 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Ring (chemistry) 01 natural sciences Skin core 0104 chemical sciences Core (optical fiber) chemistry.chemical_compound Distribution (mathematics) chemistry Transmission electron microscopy Orientation (geometry) Contrast (vision) General Materials Science Composite material 0210 nano-technology media_common |
| Zdroj: | Carbon. 109:444-452 |
| ISSN: | 0008-6223 |
| DOI: | 10.1016/j.carbon.2016.08.022 |
| Popis: | The continuous changes in orientation angle (OA) across longitudinal sections of high strength polyacrylonitrile-based carbon fibers with circular cross sections were investigated by transmission electron microscopy. A contrast ring was observed in some cross-sections, displaying two contrast zones in the longitudinal section. Two types of OA distribution features were found in the absence or presence of contrast zones. Contrast zones were confirmed as the symbol of the skin-core structure and the boundaries between the skin and core. The high preferred orientation of the basal planes was first identified in the contrast zone, which presented an OA inflexion point (OIP) in the OA plot. The OIP was also detected in the contrast zone for the self-prepared carbon fibers. The OIP and contrast ring shifted towards the core as the preoxidation time increased. For a preoxidation time of 8 h, both the OIP and contrast ring disappeared. A mechanism, based on the stress-induced alignment of the basal planes, was proposed to account for the formation of the OIP. |
| Databáze: | OpenAIRE |
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