Castor Oil - Glycerol Blends as Polyols for Rigid Polyurethane Foams

Castor oil is a relatively inexpensive and renewable source of hydroxyl groups. This makes use of castor oil in polyols for polyurethane very attractive. We have prepared a simple castor oil based polyol for rigid polyurethane foam application. The polyol is a physical blend of castor oil and glycerol. Glycerol acts as a cross-linker which gives the foam sufficient rigidity and reduces shrinkage. The foam samples are characterized by measuring density, % linear shrinkage, % closed cell content and compressive strength. Reaction injection moulding machine trials for the polyol are carried out. The amount of castor oil in the polyol which gives foams with properties comparable to commercial polyurethane foams, is about 76 % by weight of the base polyol, which is higher than the earlier reported values.