低温溶液缩聚PPTA共聚物的直接湿法纺丝研究

Direct wet spinning process of PPTA prepared by low-temperature solution polycondensation

采用低温溶液缩聚法,在聚对苯二甲酰对苯二胺(PPTA)聚合体系中引入了一定量的4,4'-二氨基二苯醚(4,4'-ODA),制备出了高黏度的改性PPTA纺丝原液,并直接进行湿法纺丝;研究了使用不同黏度的纺丝原液时,拉伸倍数、凝固浴温度、凝固浴浓度等纺丝工艺条件对初生纤维力学性能的影响,确定了最佳的湿法纺丝条件;借助扫描电镜、热重分析仪、红外光谱、X射线衍射对纤维的结构和性能进行了表征。结果表明:4,4'-ODA被成功地引入到PPTA中,但改性PPTA的结晶性能和耐热性能下降;当改性PPTA纺丝原液的比浓对数黏度(ηinh)从2.12 dL/g增大至2.58 dL/g,拉伸倍数从1.25增加至2.27时,改性PPTA纤维的强度均有所增加;最佳纺丝条件为改性PPTA的ηinh2.58 dL/g,纺丝温度50℃,拉伸倍数2.27,凝固浴为N-甲基吡咯烷酮与水的体积比1∶9,凝固浴温度30℃,在此条件下可制得改性PPTA初生纤维的断裂强度为4.22 cN/dtex,断裂伸长率为24.9%,模量为105.98 cN/dtex。

The polymerization system of poly（ p -phenyleneterephthalamide） （PPTA） was added with a certain amount of 4,4＇- diaminodiphenyl ether （4,4＇-ODA） to produce a high-viscosity modified PPTA spinning solution which was directly spun into fibers via wet spinning process. The effects of spinning process conditions, such as draw ratio, coagulation bath temperature and concentration, on the mechanical properties of as-spun fibers prepared from the spinning solution with different viscosity were studied. The optimal wet spinning conditions were decided. The structure and properties of the fibers were characterized by scanning electronic microscopy, thermogravimetric analysis, infrared spectrometry and X-ray diffraction. The results showed that 4, 4＇-ODA was successfully introduced into PPTA, but impacted the crystallization behavior and thermal resistance of modified PPTA ; the strength of the modified PPTA fiber was increased in some degree when the reduced inherent viscosity （ ηinh ） of the modified PPTA spinning solution was increased from 2. 12 dL/g to 2.58 dL/g and the draw ratio was increased from 1.25 to 2.27;and the as-spun modified PPTA fiber had the breaking strength of 4.22 cN/dtex, elongation at break 24.9% and modulus 105.98 cN/dtex when the spinning conditions were optimized as： ηinh of modified PPTA 2.58 dL/g, spinning temperature 50 ℃, draw ratio 2.27, N-methylpyrrolidone-and-water volume ratio of coagulation bath 1 ： 9, coagulation bath temperature 30 ℃.