主链含柔性单元聚酰亚胺纤维的制备及性能

传统聚酰亚胺(PI)具有典型的刚性棒状结构及强烈的分子链间相互作用,赋予其优异的力学性能、突出的耐热稳定性及耐紫外辐照性能等。然而,刚性的大分子结构使PI初生纤维后处理较为困难,力学性能不佳。为解决这一问题,在PI主链中引入柔性醚键单元,明显改善了纤维的高温拉伸性能。同时,通过调节主链中醚键单元含量及纤维后处理工艺,实现了PI化学结构及纤维聚集态结构的有效调控,明显提升了纤维的力学性能。当分子结构中柔性醚键单体物质的量分数为20%,在500℃牵伸时,拉伸强度达到2.47 GPa,模量为73.78 GPa,断裂伸长率为4.1%。

Preparation and Properties of Polyimide Fibers Containing Flexible Ether Units on the Backbone

Polyimide fibers have a typical rigid rod-like backbone and strong intermolecular interaction,which endowed them excellent thermal stability,superior irradiation and chemical resistance.However,the high rigidity of traditional PI chains brings some difficulties for the fiber spinning and thermal treatment,which result in the unsatisfied mechanical behavior of prepared PI fibers.For changing this situation,the flexible ether units were incorporated into the PI backbones.The results demonstrated that the spinning and thermal treatment processabilities,and meanwhile,mechanical properties of prepared PI fibers were greatly improved by controlling the content of ether units in the backbone and the aggregation structures of fibers.As the mole content of the ether-containing diamine reaches 20 mol%and the hot-drawing temperature was 500℃,the resultant fiber exhibited a tensile strength of 2.47 GPa,a initial modulus of 73.78 GPa and a tensile strain of 4.1%.