New formulations of novel polyurethanes based on cardanol-formaldehyde resin, polypropylene glycol and two different aliphatic diisocyanates viz., hexamethylene diisocyanate(HDI) and isophorone diisocyanate(IPDI) are reported. Cardanol based novolac type phenolic resin has been condensed with hexamethylene diisocyanate/ isophorone diisocyanate to produce rigid polyurethanes. Tough polyurethanes have been produced by condensing the commercially available polyol, polypropylene glycol-1200(PPG-1200) with the above system. The physicochemical, mechanical and thermal properties of polyurethanes have been studied. These studies revealed better mechanical properties and higher thermal stability of rigid polyurethanes and also the high performance character of the isophorone diisocyanate based polyurethanes with respect to their mechanical and thermal properties when compared with those of the hexamethylene diisocyanate -based polyurethanes
