Molecular weight distribution in batch hydrolytic polymerization of caprolactam

Abstract

Nylou-8 is generally manufactured by the hydrolytic polymerization of e-caprolactam. While the kinetics of the polymerization processes have been widely investigated, only one report has been devoted to a study of the molecular weight distribution (MWD) of the resulting polymer. Gupta et al. modeled batch polymerization of caprolactam by integrating balance equations for all polymer molecules having a dp of up to 300 and reported MWD. The equations used were similar to (1)-(9) listed in the next section except that they considered the presence of catalyzing acid and cyclic oligomer formation also. A maximum value for dp has to be assumed to integrate the equations due to their coupled nature, and it was assumed to be 800. However, the procedure employed by these workers is time consuming as it involves integration of 300 coupled nonlinear differential equations. Thus Gupta et al. reported that the calculation took 4 h on a DEC-1090 Computer system to reach a batch time of 16 h. Clearly an alternate less time-consuming procedure is required for simulation of and dynamic studies on the reactor. Such a procedure would be useful in simulating continuous reactors as well. In the present work a less time-consuming method based on the work of Min has been developed to model the batch hydrolytic polymerization of caprolactam.