Ethanolamine solutions foaming

Example 5. Glycolysis of Polyurethanes with Propylene Oxide after Pretreatment with Ethanolamine.55 A rigid polyurethane foam (ca. 100 g) was dissolved in 30 g ethanolamine by heating. Excess ethanolamine was stripped, leaving a clear solution. Infrared and GPC analysis indicated that the clear solution obtained contained some residual polyurethane, aromatic polyurea, aliphatic polyols, aromatic amines, and N,N -bis(f -hydroxyethyljurea. Next the mixture was dissolved in 45 g propylene oxide and heated at 120°C in an autoclave for 2 h. The pressure increased to 40 psi and then fell to 30 psi at the end of the 2-h heating period. The product was a brown oil with a hydroxyl number of485. 

Ballard (1986) suggests checking the glycol pH periodically and keeping it in the range of 7.0 to 7.5 by the addition of borax, ethanolamine (usually triethanolamine), or other alkaline chemicals. Too high a pH (e.g., over 8.0-8.5) is undesirable because it can increase the tendency of the solution to foam and form emulsions with hydrocarbons. Figure 11-36, from... 

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