Preparation technology of poly(p-phenylene terephthalamide)

Abstract

The invention discloses a preparation technology of poly(p-phenylene terephthalamide). The steps include: adding 15g-20g of N-methylpyrrolidinone and 20g-30g of CaCl2 into a reaction kettle to prepare an N-methylpyrrolidinone-calcium chloride solution; adding 16g-18g of p-phenylenediamine powder into the N-methylpyrrolidinone-calcium chloride solution, introducing dry nitrogen and performing stirring continuously until the powder is completely dissolved; cooling the solution, then adding 12g-15g of paraphthaloyl chloride powder, carrying out reaction for 15min-17min to obtain a paraphthaloyl chloride-p-phenylenediamine-CaCl2 solution; preparing a paraphthaloyl chloride solution with a concentration of 25%-30%; adding the paraphthaloyl chloride-p-phenylenediamine-CaCl2 solution and paraphthaloyl chloride solution according to a ratio of 2:1 into a double-screw reactive extruder to carry out reaction for 5min-6min, and extruding poly(p-phenylene terephthalamide) powder; washing the powder with cold water several times to neutral, and performing drying at 120DEG C-130DEG C for 4.5h-5.5h, thus obtaining a light yellow poly(p-phenylene terephthalamide) polymer. The method is accurate in measurement, and can realize continuous preparation of polymers with high relative molecular mass.

Description

technical field [0001] The invention relates to the technical field of poly-p-dianiline preparation, in particular to a preparation process of poly-p-dianiline terephthalamide. Background technique [0002] Poly(p-phenylene terephthalamide) is a liquid crystalline rod-shaped molecule. Due to the rigidity of the molecular chain, it has lyotropic liquid crystallinity, and it is easy to form anisotropic texture under the action of shear force in the solution. . It has high heat resistance, the glass transition temperature is above 300°C, the thermal decomposition temperature is as high as 560°C, and the strength retention rate is 84% ​​after being placed in the air at 180°C for 48 hours. High tensile strength and initial modulus of elasticity, fiber strength 0.215 Newton / denier, modulus 4.9~9.8 Newton / denier, specific strength 5 times that of steel, compressive and flexural strength only lower than inorganic fibers when used in composite materials . Stable thermal shrinkage ...

AI Technical Summary

Problems solved by technology

However, during the polycondensation reaction, the product is insoluble in the solvent, and its phase separation occurs quickly, changing from a liquid state to a viscoelastic gel substance similar to a solid, which makes heat transfer and mass transfer difficult during the reaction process, and limits the molecular chain. growth, the distribution of molecular chains is wider