SYMPOSIA PAPER Published: 01 January 1992

Chemical Characterization of Cross-Linked Polyurethane Films


The chemical composition and the physical properties of two-component polyurethane coatings are influenced by the curing conditions, viz. relative humidity and temperature. Apart from the formation of urethane, carbon dioxide can be released by hydrolysis of the isocyanate groups, leading to the formation of urea groups.

Chemical-analytical methods have been developed to characterize cross-linked polyurethane coatings based on hydroxy-functional acrylic resins and trifunctional isocyanates. Spectroscopic and wet chemical methods as well as carbon dioxide measurements were applied. Quantitative data were obtained on the content of isocyanate, hydroxyl, and amino groups and on urethane and urea cross-links.

The influence of the curing temperature, relative humidity, and type of hydroxyl groups on the network structure has been investigated. The relative humidity influences the composition of the coating cured at ambient temperature. During curing at elevated temperatures, the relative humidity hardly affects the chemical structure of the film. However, during storage after baking, urea groups are formed.

Author Information

van der Ven, LGJ
Akzo Research Laboratories Arnhem, SB Arnhem, The Netherlands
van Houwelingen, GDB
Akzo Research Laboratories Arnhem, SB Arnhem, The Netherlands
Lamping, RR
Akzo Research Laboratories Arnhem, SB Arnhem, The Netherlands
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Developed by Committee: D01
Pages: 148–156
DOI: 10.1520/STP17852S
ISBN-EB: 978-0-8031-5183-3
ISBN-13: 978-0-8031-1465-4