A combination of reduced graphene oxide (rGO) and hydrated sodium metaborates (SMB) were tested as a PIN fire safety solution for several cellulose products, including particle board and cellulose fibre based structures. rGO was produced by exfoliating graphite flakes (using acid and potassium manganese oxide).
The cellulose products were treated by soaking for 5 hours at 60°C in an aqueous solution of rGO and SMB, resulting in impregnation by SMB and surface coating by rGO to a total loading of up to 13%. Fire testing was carried out by exposing both untreated and treated cellulose materials to a gas flame and by heating them on a hot plate (300°C) in a glass jar, to enable smoke and volatiles assessment. The SMB+rGO treated sawdust showed no self ignition and no flame propagation and UL94-V0 fire performance (3.5mm) and no vertical flame propagation for particle board. Comparable improvements in fire performance were shown with rags-paper. The jar experiments showed significant reductions in release of smoke and of volatile compounds (including hazardous fire products such as hydrogen cyanide, carbon monoxide and hydrocarbons): untreated sawdust showed release of smoke from 3 minutes and of other organic compounds from 10-20 minutes, whereas the SMB-rGO treated sawdust showed no observable smoke or volatiles. The authors suggest that the fire resistance and smoke / volatile emission reduction performance of this PIN combination is due to the heatsink effect of the hydrated sodium metaborates and the structural enclosing char layer generated with the graphene oxide.
“Graphene borate as an efficient fire retardant for cellulosic materials with multiple and synergetic mode of actions” M. Nine et al., Applied Materials & Interfaces (ACS Publications) 2017 http://dx.doi.org/10.1021/acsami.7b00572