Macromolecular Reaction Engineering

Cover: Step-growth polymerization of glycerol is monitored using in-line ATR-FTIR spectroscopy. Conversion monitoring is accomplished using a univariate method by following the change in the absorbance of the OH peaks in the infrared reactor spectra throughout the course of polymerization. Further details can be found in the article by S. Salehpour, M. A. Dubé* on page 85.

This issue of Macromolecular Reaction Engineering contains articles of the Special Series “Sensors, Process Control and Modeling”.

In a free-radical copolymerization the reactivity of each monomer pair is characterized by suitable reactivity ratios. To support the experimental activity monomer and radical reactivity ratios are calculated through an approach based on quantum chemistry. A collection of entirely computational reactivity ratios for a variety of copolymers is shown proving the potential of the proposed tool.

Step-growth polymerization of glycerol is monitored using three different techniques: water production monitoring, hydroxyl value calculation, and ATR-FTIR spectroscopy. In-line or off-line ATR-FTIR spectroscopy is a successful method for monitoring the reaction up to medium conversion and for monitoring composition in polyglycerol hydrogel production.

A model to predict the rates of undesirable reactions in low-moisture, high-temperature finishing stage of nylon 66 production is presented. Parameters are ranked based on their influence on model predictions, correlation with other parameters, and uncertainty in initial guesses. An MSE criterion is used to determine which parameters should be estimated to match end-group and gas evolution data.

Catalytic chain transfer is successfully implemented in continuous emulsion polymerization in a pulsed sieve plate column. Control over the MWD can be achieved by adding ppm-levels of the active cobalt(II) complex. The results clearly illustrate that catalytic chain transfer is a promising technique for molecular weight control for large-scale (continuous) emulsion polymerization processes.