PAN分子环化行为对纤维结构及性能的影响

Effect of the molecular cyclization on the structure and properties of polyacrylonitrile fibers

预氧化阶段是链状聚丙烯腈 (PAN)分子演变为耐热梯型结构的过程。文中借助IR ,X ray及纤维应力 形变关系初步探索了PAN纤维预氧化过程中晶区和非晶区分子的环化行为对纤维结构及性能的影响规律。结果表明 ,PAN纤维在预氧化初期的环化反应主要发生在纤维的非晶区 ,中后期反应则在晶区和非晶区进行。从预氧化过程中纤维强度及拉伸 形变曲线变化规律认为PAN纤维早期的环化反应主要在分子内进行。

The linear chain structure is transformed into a planar ring structure during the oxidative stabilization of polyacrylonitrile(PAN) precursor fibers. In this paper, the effect of the molecular cyclization in the crystal and amorphous area on the structure and properties of PAN fibers was studied by IR, X-ray diffraction and the F-ε curve. The results showed that the early cyclization occurs chiefly in the crystal area and the later cyclization takes place both in the crystal and amorphous area. It can be concluded by the fact of the declining of tensile strength and the change of the stress-strain curve during the pre-oxidation of the different PAN fibers that the intramolecule cyclization dominates in the early reaction of PAN fibers.