Design of solid foams for flame retardant based on bionanocomposites systems

Abstract Bionanocomposites are hybrid materials obtained from the interaction between two or more components. The construction of this type of material comes from a continuous phase, usually organic, and the dispersed phase, usually inorganic. Both phases are naturally occurring and at least one of them has a nanoscale structure. The bionanocomposites in this work were synthesized from the biopolymers rice starch and pectin reinforced by the clay mineral palygorskite. During synthesis, the freeze-drying method was used for production of low-density solid foams. Spectroscopic techniques were applied in order to identify the interaction mechanism established between the inorganic fibers and the polysaccharide chains, which is established between the hydroxyl groups in the biopolymers and the silanol groups at the external surface of the palygorskite fibers. Besides, X-ray diffraction showed that the structure of palygorskite was not affected during the synthesis and Energy-Dispersive X-ray spectroscopy (EDX) revealed a good dispersion of palygorskite on biopolymers. Horizontal burning tests were carried out based by ASTM D4986–03 for a preliminary study of flame-retardant materials, revealing that bionanocomposite foams based on rice starch with palygorskite content > 5% behave as auto-extinguishable materials.