Flame retardant rigid polyurethane foam derived from biobased polyols and water as Co-blowing agent: Synergistic effect of expanded graphite and boron nitride

Using a bio-based polyol system one-shot free-rising method, bio-based flame-retardant rigid polyurethane foam (FR-RPUF) was prepared. Environmentally friendly blowing agent (Cyclopentane) and co-blowing agent water along with expanded graphite (EG) and boron nitride (BN) were used as admixtures to develop a synergistic flame-retardant composite at a variable ratio of EG and BN respectively. The flame retardancy of the composite was evaluated using various techniques like burning tests, UL 94, and cone calorimetry. At the same time, the morphological aspects and functional groups were analyzed by scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR) respectively. The FR-RPUF synthesized using EG and BN at a ratio of 1:1 has impressive flame-retardancy and smoke-suppressing properties, with a "V-1" rating in the UL-94 vertical burning testing. Additionally, EG/BN- FR-RPUF has a compressive modulus of 4.92 MPa, making it suitable for discontinuous panel applications.