Synthesis and characterization of rigid polyurethane foam containing phosphorus based flame retardant

Rigid polyurethane foams have been used in a wide range applications due to their distinguished heat insulating and good physic-mechanical properties. Recently, rigid polyurethane foams are applied in many industrial areas such as adhesives, paints, constructions, automotives, household appliances, etc. Meantime, the rigid polyurethane foams have high surface area thus they are specially flammable. For that reason more attention has been paid to enhance the flame retardancy of polyurethane foams through numerous studies. The mostly used flame retardants are halogenated, phosphorus and nitrogen based additives, although the use of halogenated compunds is limited due to environmental effects such as toxic smoke releasing. Thus, the recent studies are focused towards to phosphorus based flame retardants. Phophorus based additives have wide range scale including phosphates, phosphonates and phosphine oxides. In this study, phosphorus based flame retardant bis(3-hydroxyaminophenyl)phenyl phosphine oxide (BHAPPO) was synthesized. It is used in rigid polyurethane foam with different contents to reduce the flammability of polyurethane. The characterization of BHAPPO was investigated by FT-IR, 1H-NMR and 31P-NMR spectrums and DSC analysis. To further investigation of flammability of rigid polyurethane foam, ammonium polyphosphate (APP) was compounded with BHAPPO and this mixture was used to prepare rigid polyurethane foam with different proportions. The flame retardant properties of rigid polyurethane foams were analyzed by LOI and TGA tests. The morphological properties was analyzed by SEM whereas mechanical properties was investigated by compression test.