Cellulose Nanocrystals/Melamine/Phytic Acid Nanocomposites as Thermally Insulating and Flame-Retardant Structural Materials

Traditional halogenated flame retardants (FRs) have been severely hindered because they are toxic and hazardous carcinogenic byproducts during their application. In this study, we present a biobased FR composite consisting of cellulose nanocrystals (CNCs) modified with melamine (MEL) and phytic acid (PA) through successive grafting and electrostatic adsorption processes. It was found that the CNC/MEL/PA nanocomposite had a noticeable highly improved thermal blocking performance of the cellulose nanofibril aerogel, excellent carbon layer formation, and high thermal insulation ability because of a synergistic FR effect between the components in both the condensed and gas phases. These findings highlight the potential of nanoscale engineering in producing structural foams with excellent fire-retardant properties using cellulose and other nanosized fibrous biomaterials.