Development and characterization of flame retardant property in flexible polyurethane foam

Abstract

Polyurethane foam (PF) is an essential polymer which is widely used in everyday applications either directly or indirectly by the fast moving world. By changing the composition of polyol and isocyanate, these foams can be classified into rigid polyurethane foams (PUFRs) and flexible polyurethane foams (PUFFs). Due to the open cell structure, low decomposition temperature of the monomers, polyurethane foams (PFs) are easily prone to flammability which can prove to be hazardous to its end users. In this present study, a list of potential flame retardants (FRs) such as expandable graphite (EG), magnesium hydroxide (MGH), nano-titanium dioxide (NTD), organo-montmorillonite (OMMT), and MGH with OMMT, EG as a synergetic combinations were used. EG was prepared at the laboratory scale and its morphology was analyzed by scanning electron microscope (SEM). The SEM substantiates the formation of worm like structure in EG which helps in suppressing the growth of flame. Various testing methods were used to characterise the generated PUFFs, including morphology using optical microscope (OM), functional groups using Fourier infrared spectroscopy (FTIR), and flame retardant (FR) property using an Underwriters laboratories (UL) 94 horizontal burning (HB). An OM image confirms the formation of open cell structure which shows PUFF. The peak in the range 2270 cm−1 and 2240 cm−1 was not observed in the FTIR spectra for any of the PUFF samples prepared. This demonstrates and proves that the isocyanate utilised is totally transformed to PUFF, implying that urea and urethane linkages are formed with the addition of polyol and fillers. Among all PUFFs, the UL 94 HB test affirms that the combination of EG + MGH has the best FR property with 0.27 mm/s rating because of the synergistic effect. This confirms the suitability of PUFF in applications when compared to the other chosen in the present investigation.