原丝组成及升温速率对腈纶短纤维预氧化工艺的影响

THE EFFECTS OF PRECURSOR COMPOSITION AND HEATING RATE ON THE PREOXIDATION PROCESS OF POLYACRYLONITRILE STAPLE FIBERS

民用腈纶短纤维经松弛状态下预氧化处理可制备适合纺织加工的阻燃耐热纤维。本文通过力学性能测定、差示量热分析、广角X—射线衍射分析、极限氧指数测定等研究了原丝的共聚组成及升温速率对预氧化工艺及氧化纤维的结构和性能的影响。结果表明在几种原丝中如含有衣康酸组分,由于其在DSC谱图中表现出较展宽的环化放热峰,因而较适合于实际的氧化处理工艺。氧化纤维的表现环化度、芳构化指数以及极限氧指数均随升温速率的降低而增加,但氧化纤维的力学性能亦随之下降,可纺性变差。选择0.5℃/min升温速率,可较理想地得到既满足纺织加工要求又具备优良的阻燃耐热性能的氧化纤维。

By using preoxidation treatment under relaxed condition commercial polyacrylonitrile staple fibers can be applied for manufacturing heat-resistant and flame-retardant fibers with suitable textile processability. In this paper, by means of measurements of mechanical properties, DSC, WAXD and limiting oxygen index, the effects of precursor composition and heating rate on the preoxidation process and on the structure and properties of the fibers are studied. The results show that for several kinds of precursors those containing units of itaconic acid possess a rather wide cyclization exothermic peak in the DSC thermogram and thus are favorably suitable for the practical oxidation process. The apparent cyclization degree, aromatization index and limiting oxygen index of the oxided fibers all increase with the decreasing heating rate, however, the mechanical properties as well as the textile processability of the oxided fibers decrease. Choosing 0.5℃/min as heating rate will result in oxided fibers with excellent heat-resistant and flame-retartant properties as well as with good textile processability.