Exploring the Reaction Heat Controlling and Engineering Scale Law in the Process to Synthesis PPTA Using Low-Temperature Solution Polycondensation

We proposed a method to enhance the heat removal in the synthesis process of PPTA (p-phenylene terephthalamide) by adding liquid nitrogen. Compared to the indirect heat removal method by ice-water bath, the heat removal method with liquid nitrogen can absorb reaction heat in much larger amount, and consequently allows the operation at an obvious lower temperature. The high inherent viscosity (ηinh) of the PPTA suggests that the quality of the product is very high, indicating the good temperature control by using liquid nitrogen. The results indicate that the introducing of liquid nitrogen effectively transfers the reaction heat to avoid overheating during the polymerization of PPTA, with simple operation process and low cost.