The Synthesis Of Poly (P-phenylene Terephthalamide)

PPTA fiber named as aramid fiber 1414, because of its molecular structure of amide groups in benzene ring para(1, 4), between poly benzene formyl m-phenylene diamine aramid called fiber 1313.Aramid fiber is a new type of high-tech synthetic fiber. Because of aramid fiber molecular chain with strong rigidity, aramid fiber has high heat resistance, can reach 590 degrees, the highest temperature of thermal decomposition temperature as high as 300 degrees above the glass transition temperature. Aramid fiber also has the characteristics of high tensile strength and high modulus, its fiber strength is as high as 0.215 N·d-1, strength is five times the strength of steel, as a composite material, compression and bending strength of aramid fiber is also high, behind the inorganic fibers. In addition, aramid fibers have the characteristics of high insulation and resistance to acid and alkali corrosion.Aramid 1414(PPTA) as its high strength, high modulus, resistance to chemical corrosion properties, are widely used in aerospace, electrical appliances and special product development and other fields. Commonly used to aggregate the preparation of PPTA by low temperature polycondensation method, reaction solvent with dimethyla cetamide(DMAC), N-methyl pyrrolidone(NMP) and tetramethyl urea, polymerization conditions and molecular weight of the solvent, the impurities to the product has a great influence, in the end of the polymer dissolved in concentrated sulfuric acid made fiber spinning technology.In this paper,the low temperature solution polycondensation method is introduced 4,4’- diamino diphenyl sulfone(4,4’-DDS) as the third monomer to adopted in the solvent system of dimethyla cetamide(DMAC)- lithium chloride(LiCl) to modify the PPTA. The synthesis of copolymers were characterized by Infrared analysis, thermogravimetric analysis, Solubility test.Investigate the effects of reaction time, reaction temperature, the amount of the third monomer addition, the amount of LiCl cosolvent, and the molar ratio of monomer on copolymer product inherent viscosity. The results show that the high inherent viscosity, good solubility, good thermal stability copolymers would obtaine after the co-condensation.