• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Structure/property relationships of poly(3-alkylthiophenes) and their blends with ultrahigh molecular weight polyethylene.
【24h】

Structure/property relationships of poly(3-alkylthiophenes) and their blends with ultrahigh molecular weight polyethylene.

机译：聚（3-烷基噻吩）及其与超高分子量聚乙烯的共混物的结构/性质关系。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Poly(3-alkylthiophenes) form a class of solubilized, electrically conductive polymers. Although most intrinsically conductive polymers are intractable, and therefore not easily oriented, the poly(3-alkylthiophenes) have been rendered processable through the attachment of alkyl side chains. Poly(3-alkylthiophenes), with side chain lengths of 3, 4, 6, 8, and 12 carbon atoms, were synthesized using an FeCl{dollar}sb3{dollar} coupling agent. The molecular weights were reasonably high, but the polymerization reaction resulted in macromolecules containing considerable fractions of regiospecific miscouplings. These miscouplings may influence the effectiveness of {dollar}pi{dollar}-{dollar}pi{dollar} overlap, which is essential to both the electrical and mechanical properties.; When precipitated from good solvents, the polymers crystallize as lamellar structures, without appreciable side chain interdigitation. Precipitation from marginal solvents, on the other hand, results in the formation of high aspect ratio semicrystalline whiskers in which the molecular axis is oriented normal to the long axis of the whisker. The likelihood of whisker formation increases as the side chain length is reduced.; The attachment of side chains with more than four carbon atoms results in polymers which may be easily wet spun into continuous filaments. Elevated temperature tensile drawing of the fibers resulted in enhanced molecular orientation, and increased electrical and mechanical properties.; Although mechanical properties of the undoped polymers were improved by tensile drawing, both the stiffness and strength were well below those of the unsubstituted polymer. A simple model accounting for both cross-sectional dilution, by the alkyl side chains, and the fraction of regiospecific miscouplings is introduced to account for these differences. Good agreement was observed between the calculated and experimentally determined stiffness values for both doped and undoped polymers. A linear dependance between electrical conductivity and tenacity was observed, independent of side chain length.; As a means of improving the mechanical properties, the poly(3-alkylthiophenes) were solution blended with ultra-high molecular weight polyethylene (UHMW PE). The existence of a preformed polyethylene substructure resulted in reduced percolation thresholds. Tensile drawing of both plasticized and unplasticized blends resulted in phase separated composites with strength and stiffness values approaching those of neat UHMW PE, while still maintaining useful levels of electrical conductivity.
机译：聚（3-烷基噻吩）形成一类可溶解的导电聚合物。尽管大多数本征导电聚合物是难处理的，因此不易取向，但是聚（3-烷基噻吩）已通过烷基侧链的连接而变得可加工。使用FeCl {dollar} sb3 {dollar}偶联剂合成了具有3、4、6、8和12个碳原子的侧链长度的聚（3-烷基噻吩）。分子量相当高，但是聚合反应导致大分子包含相当大比例的区域特异性误偶联。这些误耦合可能会影响pi和重叠的有效性，这对于电气和机械性能都是必不可少的。当从良好的溶剂中沉淀出来时，聚合物会结晶成层状结构，而没有明显的侧链叉指。另一方面，来自边缘溶剂的沉淀导致形成高纵横比的半晶须，其中分子轴垂直于晶须的长轴取向。晶须形成的可能性随着侧链长度的减少而增加。侧链与四个以上碳原子的连接产生的聚合物很容易湿纺成连续的长丝。纤维的高温拉伸拉伸导致增强的分子取向，并增加了电气和机械性能。尽管通过拉伸拉伸可以改善未掺杂聚合物的机械性能，但其刚度和强度均远低于未取代聚合物。引入了一个简单的模型，该模型考虑了通过烷基侧链的横截面稀释和区域特异性误偶联的比例，以解决这些差异。对于掺杂和未掺杂的聚合物，在计算和实验确定的刚度值之间观察到良好的一致性。观察到电导率和韧性之间的线性相关性，与侧链长度无关。为了改善机械性能，将聚（3-烷基噻吩）与超高分子量聚乙烯（UHMW PE）溶液共混。预制的聚乙烯亚结构的存在导致降低的渗漏阈值。增塑和未增塑混合物的拉伸拉伸导致相分离的复合材料，其强度和刚度值接近纯UHMW PE的强度和刚度，同时仍保持有用的电导率水平。

著录项

  • 作者

    Moulton, Jeffrey David.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1991
  • 页码 199 p.
  • 总页数 199
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号