紫外光对芳香族聚噁二唑纤维结构和力学性能的影响

采用一步三阶段式控制法制备了一系列结构及环化率不同的芳香族聚噁二唑纤维,并研究了紫外光老化前后纤维结构和力学性能的变化,初步探讨了其光老化机理。结果表明,光老化24h,纤维强度保持30%,特性黏度保留60%;X射线衍射谱图显示老化后纤维晶粒尺寸发生变化;红外图谱表明老化后1710cm-1附近产生新的羰基吸收峰,可能生成羰基化合物;从扫描电镜观察到老化后试样表面变得粗糙,出现沟槽等现象。  

In situ-polymerization of fluorinated polyoxadiazole with carbon nanotubes in poly(phosphoric acid)

In the present work, in-situ polymerizations of fluorinated polyoxadiazole through a polycondensation reaction of A-A (hydrazine sulphate) and B-B (aromatic dicarboxylic acid) monomers with multiwalled carbon nanotubes (MWCNT) in poly(phosphoric acid) were performed in the frame of time 3 to 48 h. The effect of acid treatment in polyphosphoric acid on the CNT structure was analyzed by SEM, TGA and FTIR. Fluorinated polyoxadiazole/MWCNTs soluble in organic solvents with high molecular weights (around 200 000 g/mol) could be synthesized in 3 h. The fluorinated polyoxadiazole/MWCNTs exhibits high thermal stability with degradation temperature at about 460 °C.  

Sulfonated polyoxadiazole composites containing carbon nanotubes prepared via in situ polymerization

In the present work, in situ polymerizations of sulfonated polyoxadiazole through a polycondensation reaction of A–A (hydrazine sulphate) and B–B (aromatic dicarboxylic acid) monomers with carbon nanotubes in poly(phosphoric acid) were performed. The structures of composites were characterized by elemental analysis, Raman and FTIR spectroscopy. The sulfonated polyoxadiazole composites with high molecular weight (in the order of magnitude of 10⁵ g/mol) are soluble in organic solvents and can be cast as dense films. They exhibit good mechanical properties (storage modulus up to around 4 GPa at 300 °C) and an electrical conductivity in the order of 10⁻⁵ S m⁻¹. The composites can be used at temperatures as high as 470 °C.