The conventional low-temperature method of solution polycondensation was developed to realize the reaction of p-phenylenediamin and terephthaloyl chloride for the preparation of poly(p-phenylene terephthalamide)(PPTA). Some main factors influencing this process were investigated to determine the optimum condition for high molecular weight. Experiment showed significant slowing of the reaction and gradual deviation of second-order reaction kinetics due to diffusion control. These phenomena were studied theoretically via dynamic Monte Carlo simulation. A concise expression,_n～c_0^(-0.88)·t^(0.37), was proposed to describe the diffusioncontrolled polycondensation process as a function of the monomer concentration and reaction time. The theoretical results provided a good description of diffusion-effected kinetics for the polycondensation process of PPTA, and demonstrated good agreement with the experimental data. Some differences of scaling relations between model and experiment results were also discussed.
聚合反应过程的热量管理是影响聚合物品质以及工程放大成败的关键因素之一.本文通过在PPTA聚合过程中引入液氮,考察了PPTA在传统低温溶液缩聚法制备过程中,采用惰性传热介质液氮作为辅助移热介质时,对PPTA聚合过程及聚合物性能的影响.结果表明,在PPTA聚合过程中适量液氮的加入可提高其比浓对数黏度和热稳定性,改善PPTA的表面浸润性能,并且未对PPTA的化学结构、聚集态结构及液晶形态产生明显影响.在140,300及1000 L反应釜的聚合放大实验中所得聚合物的比浓对数黏度均在6 d L/g以上.
