Liquefaction of Wheat Straw and Preparation of Rigid Polyurethane Foam from the Liquefaction Products

Wheat straw was liquefied in the mixture of polyethylene glycol (PEG 400) and glycerin in the presence of acid at the temperature 130-160 degrees C. The final liquefaction products having the hydroxyl number of 250-430 mg KOH/g and the (M) over bar (n) of about 1050 can be used as the polyol component to manufacture polyurethane. A kind of polyurethane foam was prepared from liquefied wheat straw, commercial polyol, and diisocyanates in the presence of organotin catalysts and foaming agents. The polyurethane foam presented better compressive strength and thermal stability than that manufactured from diisocyanate and polyol alone. The thermal stability of PU foam was improved with the increase of [NCO]/[OH] ratio and the addition of liquefied wheat straw. The polyurethane foam presented faster biodegradation at ambient temperature than normal polyurethane foam did. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 508-516,2009