A team of researchers from China conducted study on mechanical, thermal properties and flame retardancy of rigid polyurethane foams (PUF) prepared from modified castor oil (MCO) based polyols. The polyurethane foam was prepared in two stages. The first stage is the conversion of castor oil into glycerides by alcoholysis with glycerol and pentaerythritol. Next stage is the synthesis of polyester polyols by condensation alcoholysis of castor oil and phthalic anhydride. Results from various analyses showed that components of the MCOs and commercial polyester polyol PS-3152 are similar in their foaming behaviour. Results from analyses like mechanical testing, flame retardancy testing, thermogravimetric analysis and cone calorimetry showed that PUF from modified Castor oil based polyols had a better mechanical properties and thermal conductivities than PS-3152 based Polyurethanes. High thermal stability is exhibited by MCO based PUFs, during pyrolysis.
It is also found that addition of ammonium pyrophosphate decreased their heat release rate, total heat release and mass loss, thereby having synergistic effect with phthalic anhydride polyester polyols. All of these unique properties of MCO-modified rigid PUFs were correlated to the structures of these PUFs.
These findings may lead to the development of a new type of polyurethane foam using castor oil.
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