Components in a Polyurethane

Hydrolysis of the polyurethane into its component blocks is necessary. Approximately 1 g of urethane is cut into small pieces and placed in a 125 ml Erlenmeyer flask. Sufficient 40% aqueous NaOH is added to cover the elastomer. The flask is heated gently and then refluxed for 30 min. The solution is cooled to room temperature and filtered if a precipitate is observed. The precipitate generally consists of substituted ureas. 

If the diamine portion of the polyurethane is desired, the solution is extracted with several 25 ml portions of diethyl ether. These are combined, the ether removed, and the spectrum of the diamines can then be identified from reterence infrared spectra and correlation tables. The solution is then neutralized and acidified slightly with nitric or hydrochloric acid and the glycols remaining in solution from saponification of a polyester foam must be steam-distilled to effect recovery. 

The acid portion will remain as a crystalline precipitate which can be water-washed, dried and identified by infrared. 

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