Study On The Spinning Solution Of High Molecular Weight Polyacrylonitril For Carbon Fibers

Preparation for spinning solution is an important part in the process of polyacrylonitrile-based carbon fiber production. The quality of polymer solution, not only affects the stability of spinning solution and process performance, but also indirectly affects the quality of finished fiber. Thus the preparation of uniform solution of high molecular weight polymers is very important. The sulfur sodium cyanide (NaSCN) solution was used as solvent, the preparation of the high molecular weight polyacrylonitrile (HMWPAN) spinning solution was researched with emphasis on swelling and dissolution.First, on the basis of previous research, the mixed solvent precipitation polymerization method was improved through extending the reaction time and adding additional monomers, then high molecular weight PAN is synthesized. In addition, the impact of conditions on the intrinsic viscosity of polymer dilute solution was discussed, and the linear deviation relation betweenη_sp/c and c of HMWPAN dilute solution was also investigated, and the viscosity method measuring molecular weight was amended.For HMWPAN/NaSCN system, through the determination of swelling value, the key factors of affecting the swelling process was first discussed using orthogonal analysis. Experimental results showed that the impact of concentration of NaSCN aqueous solution on swelling of the HMWPAN was the most significant, while the influence of swelling time on the swelling is very small, and it is also shown that the temperature and solid content had a certain influence on the swelling of HMWPAN. Besides, the trace amounts water contained in polymer particles and polymer particle sizes also had significant impact on the swelling of the HMWPAN. In addition, optical microscopy was used to observe the variation of polymer particles structural in the swelling process. The rotational viscometer was used to measure viscosity variation in the process of HMWPAN swelling and dissolution, and the swelling temperature was determined. Finally, the swelling process of HMWPAN was determined combining with the test results.In this paper, the DSC dissolution method was used to determine the melting temperature of HMWPAN. Meanwhile, a wide range of dissolved processes were discussed, and the dissolution technology of high molecular weight PANS was determined.Finally, the impact of the spinning solution temperature, solid content and the pulling speed on the spinnability of spinning solution was discussed through using self-assembly spinning equipment in the laboratory.