Intrinsic flame‐retardant urea formaldehyde/graphene nanocomposite foam: Structure and reinforcing mechanism

Abstract

Based on the industrialized graphene (GN) product, a series of intrinsic flame‐retardant urea‐formaldehyde/graphene‐silane coupling agent (UF/GN‐SA) nanocomposite foams were fabricated via in situ polymerization and water‐based foaming process. It was found that at low GN content, GN sheets dispersed homogeneously in the foams. Compared with neat UF foam, the composite foam exhibited circular cells with smaller cell size, narrower cell size distribution, thicker cell walls, lower porosity, and less water absorption. Introduction of 0.5 wt% GN resulted in about 29.5% decrease in pulverization ratio, 71.8% increase in compressive strength, and 132.6% increase in compressive modulus. The reinforcing mechanism of the UF/GN‐SA nanocomposite foam was explored. Due to the dense cell structure, formation of GN centered network structure, and reinforcing effect of GN, greater compressive stress was required to destruct the foam. UL‐94 V‐0 rating was achieved for the composite foams with remarkably suppressed flame expansion. POLYM. COMPOS., 40:E811–E820, 2019. © 2018 Society of Plastics Engineers