Hydrolysis of PU Polymers

Hydrolysis of a urethane group leads to the formation of an amine, an alcohol and carbon dioxide (reaction 20.1). 

From the hydrolysis of a polyether-based PU a diamine (or a polyamine) such as toluene diamine or diphenylmethane diamine, a polyol and carbon dioxide are formed. The resulting diamines are the precursors used for the synthesis of isocyanates [11,12,16,18]. The resulting polyol is the polyether polyol used for the initial synthesis of PU. Carbon dioxide results from the decomposition of the very unstable carbamic acid formed by the hydrolysis (20.2)  

By hydrolysing a polyether PU, a polyether polyol is obtained with a similar structure to those of the initial virgin poly ether polyol. For polyester PU the hydrolysis reaction is more complicated because the esteric groups of polyesters are hydrolysed back to monomers, such as diacids and glycols or polyols (reaction 20.3). 

by the hydrolysis of a PU based on a polyester derived from adipic acid and diethylene glycol (DEG) - adipic acid, DEG, diamine and carbon dioxide are obtained. 

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