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首页> 外文学位 >Continuous carbon nanofibers prepared from electrospun polyacrylonitrile precursor fibers.
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Continuous carbon nanofibers prepared from electrospun polyacrylonitrile precursor fibers.

机译：由电纺聚丙烯腈前体纤维制备的连续碳纳米纤维。

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摘要

The electrospinning process of fiber production is examined in regards to the preparation of continuous Polyacrylonitrile (PAN) nanofibers with the purpose of preparing carbon nanofibers for the reinforcement of thin films and nanocomposites. The mechanical properties and reinforcing behavior of nanofibers are expected to differ significantly from their conventional counterparts; the strength of a carbon filament increases as the diameter decreases.; Discrete lengths of partially aligned and oriented electrospun PAN fibers with diameters between 0.27mum and 0.29mum (FESEM) were prepared from solution with Dimethylformamide electrospun between 10-16kV and collected onto a take-up wheel rotating between 3.5m/s and 12.3m/s. A maximum chain orientation parameter of 0.23 is determined by dichroism (FTIR) and wide angle X-ray diffraction (WAXD) for fibers collected between 8.1m/s and 9.8m/s. Twisted yarns of aligned PAN nanofibers with an average denier of 446 and twist angles between 1.1° and 16.8° are prepared. The ultimate strength and modulus of the twisted yarns increase with increasing angle of twist to a maximum of 162+/-8.5 MPa and 5.9+/-0.3 GPa, respectively, at an angle of 9.3°. Drawing of the untwisted yarn in batch above the Tg of the material resulted in a further increase of the ultimate strength and modulus to 253+/-46 MPa and 4.8+/-0.5 GPa at a draw ratio of approximately 1:2; the ultimate strength of commercially prepared precursor fiber is 512MPa with post-treatment. A high temperature oxidation process is optimized and carbon nanofibers are prepared. The carbonized yarns are observed to exhibit graphitic structure by Raman scattering and wide angle X-ray diffraction (WAXD), although the mechanical properties are weak.; Continuous lengths of electrospun PAN yarn, provided through a collaboration, are characterized and evaluated for the production of carbon nanofiber yarn. The yarn is continuously processed and converted into carbon. Although, the yarn exhibits graphitic strucuture, the strength of the carbonized nanofiber yarn is only approximately 5% that of commercial carbon fiber prepared from the same precursor material. The poor mechanical properties are due to a loss of preferred orientation during an extended stabilization step.
机译：关于连续聚丙烯腈（PAN）纳米纤维的制备，对纤维生产的静电纺丝工艺进行了检查，目的是制备用于增强薄膜和纳米复合材料的碳纳米纤维。纳米纤维的机械性能和增强性能预计将与传统的纳米纤维显着不同。碳丝的强度随着直径的减小而增加。用直径在10-16kV的二甲基甲酰胺溶液纺丝，制备直径在0.27mum和0.29mum之间（FESEM）的部分排列和定向的电纺PAN纤维的离散长度，并收集到一个在3.5m / s和12.3m / s之间旋转的卷线轮上。 s。对于在8.1m / s和9.8m / s之间收集的纤维，通过二色性（FTIR）和广角X射线衍射（WAXD）确定最大的链取向参数为0.23。制备了排列的PAN纳米纤维的加捻纱，其平均旦数为446，捻角在1.1°至16.8°之间。加捻纱的极限强度和模量随加捻角的增加而增加，最大夹角为9.3°，最大分别为162 +/- 8.5 MPa和5.9 +/- 0.3 GPa。在材料的Tg之上分批拉伸未捻纱线会导致最终强度和模量进一步增加，达到253 +/- 46 MPa和4.8 +/- 0.5 GPa，拉伸比约为1：2；经后处理，商业制备的前体纤维的极限强度为512MPa。优化了高温氧化工艺，并制备了碳纳米纤维。尽管机械性能较弱，但通过拉曼散射和广角X射线衍射（WAXD）观察到碳化纱线显示出石墨结构。通过协作提供的连续长度的电纺PAN纱线的特性和评估，可用于生产碳纳米纤维纱。纱线被连续加工并转化为碳。尽管纱线显示出石墨结构，但碳化纳米纤维纱线的强度仅是由相同前体材料制备的商品碳纤维的强度的约5％。较差的机械性能是由于在延长的稳定步骤期间失去了优选的取向。

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  • 作者

    Fennessey, Sian F.;

  • 作者单位

    University of Massachusetts Amherst.;

  • 授予单位 University of Massachusetts Amherst.;
  • 学科 Chemistry Polymer.; Engineering General.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 209 p.
  • 总页数 209
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 高分子化学（高聚物）;工程基础科学;
  • 关键词

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