Characterisation of the fire behaviour of wood: From pyrolysis to fire retardant mechanisms

Abstract

Wood is undeniably the most useful and readily available natural raw material. However, the susceptibility of wood products to fire is one of the crucial challenges faced in the wood industry. The fire behaviour of wood is a very complex phenomenon due to the different constituents and their independent reactions to fire. This article presents a thorough overview of the flammability stages of wood. It covers pyrolysis, thermal oxidative decomposition, ignition, combustion and heat release as well as flame extinction mechanisms. In the area of flame retardancy, conventional wood fire retardants, nanocomposites fire retardants and wood modification processes are investigated. Factors such as wood species, moisture content, density, experimental conditions such as external heat flux, heat exposure time, wood permeability and porosity are some of the deterministic parameters characterising the fire behaviour. This paper is a one-stop-shop for researchers analysing wood flammability due to the inclusion of all aspects pertaining to the burning of wood.

Research Progress on the Improvement of Flame Retardancy, Hydrophobicity, and Antibacterial Properties of Wood Surfaces

“…For the most part, lignin, cellulose, and hemicellulose make up the xylem of wood [ 9 ] ( Figure 1 ). It is prone to thermal disintegration at medium and high temperatures, which releases a lot of heat, smoke, and hazardous fumes, starting fires and posing a major risk to human life [ 8 , 9 , 10 ]. The majority of researchers use added flame retardants [ 11 ] to make wood fire-resistant using straightforward physical techniques.…”

“…Following the COVID-19 outbreak, the demand for timber has been on the rise and is anticipated to do so in the upcoming years. The development trend for wood composite materials in the future is to enhance the surface function of wood and its flame-retardant, hydrophobic, and antibacterial qualities [ 10 ]. Then, the three sections of this essay are flame-retardant, hydrophobic, and antibacterial, respectively.…”

High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation

“…Water-soluble ammonium phosphate salts have been extensively used as fire-retardant (FR) additives both for solid wood and wood-based panels due to their effectiveness, very low toxicity, and competitive prices. − The FR mechanism of nitrogen-containing compounds such as ammonium, urea, and melamine primarily involves gas phase dilution resulting from decomposition into non-flammable gases, such as N 2 , at elevated temperatures to decrease the probability of wood contact with O 2 . Phosphates are very effective in enhancing the fire-retardancy of hydroxyl group-rich polymers, for example, lignocellulosic materials.…”

The curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation

“…The generated heat from combustion will maintain the pyrolysis of the material and release more volatile gases 14 . The decrease in HRR is caused by the formation of a char layer that has an insulating effect slowing down the pyrolysis process as well as hindering the transport of heat and volatile gases through the material 15,16 . The second/end peak is believed to be a result of material burn through and char cracking, which enable the escape of additional volatile gases 17 .…”

“…14 The decrease in HRR is caused by the formation of a char layer that has an insulating effect slowing down the pyrolysis process as well as hindering the transport of heat and volatile gases through the material. 15,16 The second/end peak is believed to be a result of material burn through and char cracking, which enable the escape of additional volatile gases. 17 The final decrease in HRR occurs when no more volatiles are released and the flaming combustion ends, resulting in a steady baseline.…”