【摘要】 分别采用扫描电镜(SEM)、广角X-ray衍射(WAXD)和小角X-ray散射(SAXS)研究分析了经含硫酸和尿素催化剂催化处理的Lyocell纤维在热解过程中结构、性能的变化。发现在低温热解前阶段(<200℃)随着处理温度的升高其密度增大,高于200℃后密度有所下降。纤维强度则表现出先下降后升高的变化规律,并在150℃~200℃温度区存在一个“零强度点”。在此过程中纤维聚合度也发生了类似强度的变化。同时,纤维结晶结构由纤维素II型向炭纤维的二维乱层石墨结构转化。更多还原

【Abstract】 Changes in the structure and mechanical properties during the conversion of lyocell precursors to carbon fibers were investigated by scanning electron microscopy, wide angle X-ray diffraction and small angle X-ray scattering when they were treated with a catalyst containing sulfuric acid and carbamide. It was found that the density of fibers first increased with temperature, then decreased when the temperature exceeded 200℃. The strength decreased gradually and was close to zero between 150℃ and 200℃, but then increased with increasing temperature. The degree of polymerization showed similar changes to the strength changes during pyrolysis. The crystalline structure of the cellulose II crystals in lyocell fibers was converted to a 2D turbostratic carbon structure.更多还原