The kinetics of hydrolytic polymerization of ϵ‐caprolactam

Abstract

SynopsisA method to determine the concentration of t-aminocaproic acid (ACA) in poly-t-caprolactam by high-pressure liquid chromatography is established. The polymerizations for initial water concentrations of 0.42,0.82, and 1.18 mol/kg and temperatures of 230,240,250,260,270, and 280°C were performed and concentration-versus-time curves were obtained for ACA, c-caprolactam (CL), and endgroups (EG). Each curve for ACA and EG has a maximum which increases monotonically in its value and shifts from right to left in position with increasing either the temperature or the initial water concentration. The reaction rates of CL, EG, and ACA were also evaluated numerically from the concentration data. The observed kinetic data were compared with those obtained by the numerical solution of the rate equations with Reimschuessel's kinetic constants. Good agreement is found in C L and EG concentrations but discrepancies in ACA concentration and rates are considerable, particularly in the early stage of the polymerization.

A comprehensive model for nylon melt equilibria and kinetics

“…8 Values for the end group concentrations (and caprolactam concentrations where appropriate) were used as data for fitting the model in a weighted least-squares sense.…”

“…7 Fitting literature data to empirical exThe concentration of ring oligomers is also of pressions also suffers from insufficient precision interest industrially because these materials can of data. Tai et al 8 and Giori and Hayes 6 did aldegrade the overall polymer properties. Reaction most exactly the same experiment (water Å 0.82 models have been generally in the form of eqs.…”

“…For example, the experiments of Wiloth were at a lower temperature than the average for those of Tai et al Is the higher (fitted) initial monomer content related to the lower temperature? Particularly, the data of Tai et al 8 were examined by using the overall experimental constants and looking at the initial monomer concentration that gave the best fit for each individual polymerization run. The estimated initial monomer concentrations showed no clear trends, and varied by as much as a factor of 2.…”

The simulation of hydrolytic polymerization of ϵ‐caprolactam in various reactors

“…. - (8,9), and shows rather complicated distribution, while, in the concentration map of CL, monotonical decrease is only recognized from center to wall and from top to bottom except the 9th stream.…”

Effects of End-Group Balance on Melt-Phase Nylon 612 Polycondensation: Experimental Study and Mathematical Model

“…They estimated the activation energy for the uncatalyzed amidation reaction, E u , to be 89.6 kJ mol -1 and expressed the corresponding preexponential factor, B u , as a function of both [W] and [C]. Some researchers 32,47,48 have used a combination of both second-and third-order kinetics, simultaneously estimating an uncatalyzed rate constant (k u ) and an acid-catalyzed rate constant (k c ), which are used to calculate a composite rate constant:…”