PAN纤维热松弛行为控制与聚集态结构调控

Regulation of thermal relaxation behavior and aggregation structure of polyacrylonitrile fiber

聚丙烯腈(PAN)纤维在纺丝过程中会形成受迫高弹形变,在受热条件下会出现物理收缩为代表的热松弛行为,发生解取向。通过热力学分析仪(TMA),动态力学分析仪(DMA),广角X射线衍射法(WAXD)等手段研究PAN纤维的热松弛行为,并且通过张力和温度对其进行控制。结果表明:PAN纤维纺丝过程形成的高弹形变约占10%以上,在高温下会迅速回复发生解取向。通过施加适当的张力和提高温度可以在不损失取向结构的同时将高弹形变转化为塑性形变。在张力和温度的作用下,纤维内部聚集态结构重排,分子链取向进一步提高,晶态结构进一步完善,纤维尺寸稳定性提高50%以上。研究表明经此方法处理的碳纤维微晶沿分子链排列更加规整,性能得到了有效提升。

Polyacrylonitrile(PAN) fibers which formed high-elastic deformation during the spinning process,have thermal relaxation behavior in the heat conditions, such as thermal shrinkage with disorientation. The thermal relaxation behavior of PAN fibers was investigated by thermomechanical analyzer(TMA), dynamic mechanical analyzer(DMA), wide-angle X-ray diffraction(WAXD).And PAN fibers aggregation structure changed by tension and temperature were analyzed. The results show that the forced high-elastic deformation in PAN fibers accounts for more than 10% which leads to disorientation at high temperature. With structure rearrangement under controlled conditions, the high-elastic deformation in PAN fibers can be transferred to plastic deformation by appropriate tension and temperature imposed to fibers without orientation structure loss. By imposing tension and temperature, further improvement is achieved in the regularity of aggregation structure and the orientation of the molecular chain, crystalline structure, and dimensional stability increase by more than 50%. The crystallites of PAN based carbon fibers treated by this method are more regularly arranged along the molecular chain, and the performance has been improved effectively.