The Components’ Roles in Thermal Stability and Flammability of Cork Powder

Abstract

In this study, an analysis of the influence of extractives, suberin and lignocellulosic components on the pyrolysis decomposition and fire reaction mechanisms of a cork oak powder from Quercus suber L. is presented. The summative chemical composition of cork powder was determined. Suberin was the main component at 40% of the total weight, followed by 24% of lignin, 19% of polysaccharides and 14% of extractives. The absorbance peaks of cork and its individual components were further analyzed by means of ATR-FTIR spectrometry. Thermogravimetric analysis (TGA) showed that the removal of extractives from cork slightly increased the thermal stability between 200 °C and 300 °C and led to the formation of a more thermally stable residue at the end of the cork decomposition. Moreover, by removing suberin, a shift of the onset decomposition temperature to a lower temperature was noticed, indicating that suberin plays a major role in enhancing the thermal stability of cork. Furthermore, non-polar extractives showed the highest flammability with a peak of heat release rate (pHRR) of 365 W/g analyzed by means of micro-scale combustion calorimetry (MCC). Above 300 °C, the heat release rate (HRR) of suberin was lower than that of polysaccharides or lignin. However, below that temperature it released more flammable gases with a pHRR of 180 W/g, without significant charring ability, contrary to the mentioned components that showed lower HRR due to their prominent condensed mode of action that slowed down the mass and heat transfer processes during the combustion process.

Transforming wastes into functional materials: natural cork-based physical structural components and polymers

“…While synthetic polymers may degrade and melt at relatively low temperatures, cork retains its cellular structure at high temperatures (350 °C) despite cell expansion and thinning of the cell walls, making it an ideal choice for use as an insulating layer in the event of a fire. 15,16 In addition, the material burns slowly and does not release toxic fumes when exposed to fire. Although thickness plays an important role in the effectiveness of cork, the density of a particular species largely determines the thermophysical value of the material.…”