Study On The Polymerization Technique Of Poly(m-phenylene Terephthalamide)(Aramid Fiber1313)

The meta-aromatic fiber(hereinafter PMIA) has great prospect in many industries as a new kind of high performance fibers. Until now, the few capitalist countries represented by America grasp more than90%of the world market because of the high investment cost and complex production process.The method of low temperature solution polycondensation to produce PMIA has achieved certain achievements in domestic industries, however, the products have obviously disadvantages compared with the Nomex named by Du Pont. It is attributed to that the PMIA made by Du Pont is prepared by the method of interfacial polycondensation, and it has more advantages such as better narrow molecular weight distribution which is beneficial to prepare high quality fibers, and the technology in domestic research reports are few.In this paper, we researched the two kinds of polymerization processes and compared the polymers made by the different methods. The optimum processes of low temperature solution polycondensation to produce PMIA were as follows:nitrogen protection, the moisture content of solvent was below150ppm, the initial reaction temperature was-10℃, the monomer concentration was1.0mol/L, the IPC excess2%, the stirring rate was750rpm,2-methylpyridine as acid binding agent, and the ηinh was maximum which could reach1.6dL/g. The optimum conditions of interfacial polycondensation were as follows:THF as the solvents, the reaction temperature was room temperature(20～30η), the molar ratio of CMPD/QIPC was1:1.1, the stirring rate was750rpm,2-methylpyridine as acid binding agent, and the ηinh maximum which could reach1.8dL/g.The FT-IR was used to characterize the structure, the result showed that the polymers made by the two different methods had the same structure, and the DSC further verified that they were consistent with that of PMIA. The polymer made by the method of interfacial polycondensation had better thermal stability, its decomposition temperature was418℃, and the rapid decomposition temperature was452℃.Method of GPC with SEM were used to observe the morphology and test the molecular weight distribution. The consequence further suggested that the polymer made by the method of interfacial polycondensation had the advantage of narrow molecular weight distribution, and performed good fiber-forming property.