Intrinsically Flame Retardant Polyurethane Prepared with Epoxidized Soybean Oil and Vinylphosphonic Acid

Abstract

The synthesis of novel polyol was carried out by the reaction of epoxidized soy-bean oil (ESBO) throught ring opening reaction with vinyl phosphonic acid (VPA) bearing two functional groups, vinyl and phosphonic acid. The synthesized polyol (PolP) and 4,4 -methylenebis(phenyl isocyanate) (MDI) were reacted to prepare biobased and inherently flame retardant polyurethane foam (PPPU). FTIR, 1 H, 13 C and 31 P NMR spectroscopy confirmed that the epoxy ring of ESBO was opened by phosphonic acid group of VPA, and vinyl group was not involved in the ring opening. The prepared polyurethane was characterized using fourier transformed infrared spectroscopy ( FTIR) and thermal properties were measured using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). XRD was used for crystallografic structure and SEM image of polyurethane showed smooth surface. When compared to phosphorous-free polyurethanes derived from soybean oil based polyols, PPUP exibited better flame retardant property with a limiting oxygen value index of 26.4.