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Reaction kinetics of toluene diisocynate and propanol by in situ FTIR

Reaction kinetics of toluene diisocynate and propanol by in situ FTIR Purpose – To evaluate the effect of the concentrations of isocyanate group and hydroxyl group and hydroxyl group species on the rate constants of isocyanate‐propanol reaction, and to reveal the kinetics of isocyanate‐hydroxyl reaction. Design/methodology/approach – The in situ FTIR technique was employed to measure the group concentration evolutions, by which the rate constants were determined. Besides, the FTIR was used to detect the OH absorbance shifts during reaction and the OH absorbance at different concentrations. The kinetic mechanism of isocyanate‐propanol reaction was discussed with the combination of rate constants and FTIR spectra. Findings – A new reaction mechanism, alcohol association mechanism, was proposed that could explain many phenomena. It was revealed that the rate constant was independent of the isocyanate concentration, while the concentration and species of hydroxyl groups had apparent effects on the rate constants. It was possible to calculate the number averaged degree of association of propanol with alcohol association mechanism. Research limitations/implications – The associated n ‐propanol molecules that reacted with isocyanate to form urethane were the associated dimer and trimer predominately, while the iso ‐propanol was the dimer. Practical implications – The kinetics of isocyanate‐hydroxyl reaction and the alcohol association mechanism will be helpful to understand the preparation and curing of polyurethane, and their controls. Originality/value – A new reaction mechanism, alcohol association mechanism, was proposed that could explain many phenomena that might not be interpreted by other mechanisms. The mechanism could be employed to calculate the number averaged degree of association of alcohols. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Pigment & Resin Technology Emerald Publishing

Reaction kinetics of toluene diisocynate and propanol by in situ FTIR

Z.H. Gao; J.Y. Gu; X.D. Bai
Pigment & Resin Technology , Volume 36 (2): 7 – Mar 27, 2007
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References (16)

Publisher
Emerald Publishing
Copyright
Copyright © 2007 Emerald Group Publishing Limited. All rights reserved.
ISSN
0369-9420
DOI
10.1108/03699420710733529
Publisher site
See Article on Publisher Site

Abstract

Purpose – To evaluate the effect of the concentrations of isocyanate group and hydroxyl group and hydroxyl group species on the rate constants of isocyanate‐propanol reaction, and to reveal the kinetics of isocyanate‐hydroxyl reaction. Design/methodology/approach – The in situ FTIR technique was employed to measure the group concentration evolutions, by which the rate constants were determined. Besides, the FTIR was used to detect the OH absorbance shifts during reaction and the OH absorbance at different concentrations. The kinetic mechanism of isocyanate‐propanol reaction was discussed with the combination of rate constants and FTIR spectra. Findings – A new reaction mechanism, alcohol association mechanism, was proposed that could explain many phenomena. It was revealed that the rate constant was independent of the isocyanate concentration, while the concentration and species of hydroxyl groups had apparent effects on the rate constants. It was possible to calculate the number averaged degree of association of propanol with alcohol association mechanism. Research limitations/implications – The associated n ‐propanol molecules that reacted with isocyanate to form urethane were the associated dimer and trimer predominately, while the iso ‐propanol was the dimer. Practical implications – The kinetics of isocyanate‐hydroxyl reaction and the alcohol association mechanism will be helpful to understand the preparation and curing of polyurethane, and their controls. Originality/value – A new reaction mechanism, alcohol association mechanism, was proposed that could explain many phenomena that might not be interpreted by other mechanisms. The mechanism could be employed to calculate the number averaged degree of association of alcohols.

Journal

Pigment & Resin Technology – Emerald Publishing

Published: Mar 27, 2007

Keywords: Polyurethane; Chemical reactions

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