New castor oil‐based urethane elastomers

Urethane elastomers with a wide range of properties were prepared by reaction of toluene diisocyanate, diphenylmethane diisocyanate or an aliphatic diisocyanate with a series of castor oil derivatives. The castor derivatives included amides prepared by reaction of castor oil with mono‐ or dialkanolamines, amides of ricinoleic acid with long chain di‐ and triamines, butanediol diricinoleate and the commercial products‐castor oil itself and the monoricinoleates of propylene glycol and pentaerythritol. Elastomers were also prepared from commercial polyether diols for comparison. Properties evaluated include hardness, resilience, tear strength, stress‐strain properties, compression set and resistance to water and oil. Particularly high tensile and tear strengths were obtained from the amides. Softer products with good properties were obtained from propylene glycol monoricinoleate and from mixtures of the amides with castor oil or butanediol diricinoleate. Improved products were obtained by the use of diphenylmethane diisocyanate in place of toluene diisocyanate.