Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Roger M. Rowell
    Date: 2005
    Source: Handbook of wood chemistry and wood composites. Boca Raton, Fla. : CRC Press, 2005: pages 121-138.
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (451 KB)

    Description

    The traditional question at the start of a class on thermal properties of wood is, “Does wood burn?” The students have all been warmed in front of a wood-burning fire before, so they are sure the answer is yes—but since the professor asked the question, there must be some hidden trick to the obvious answer. Going with their experience, their answer is “yes, wood burns.” But, the actual answer is no, wood does not burn. In short, wood undergoes thermal degradation as it heats up, giving rise to volatile, flammable gases which burn when they contact a source of ignition. So it is the flammable gases that burn, not the wood itself. This is, of course, an oversimplified explanation of the pyrolysis and burning processes which are the subject of this chapter. Lignocellulosic materials decompose on heating and when exposed to an ignition source by two different mechanisms. The first, dominant at temperatures below 300˚C, degrades polymers by the breaking of internal chemical bonds; dehydration (elimination of water); formation of free radicals, carbonyl, carboxyl, and hydroperoxide groups; formation of carbon monoxide and carbon dioxide; and finally, the formation of reactive carbonaceous char. Oxidation of the reactive char results in smoldering or glowing combustion, and further oxidation of the combustible volatile gasses gives rise to flaming combustion. The second mechanism, which takes over at temperatures above 300˚C, involves the cleavage of secondary bonds and formation of intermediate products such as anhydromonosaccharides, which are converted into low molecular weight products (oliosaccharides and polysaccharides), which lead to carbonized products.

    Publication Notes

    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Rowell, Roger M. 2005. Thermal properties. Handbook of wood chemistry and wood composites. Boca Raton, Fla. : CRC Press, 2005: pages 121-138.

    Keywords

    Char, oxidation, thermal properties, pyrolysis, combustion, fireproofing agents, fire testing, ignition, fire retardants, thermal degradation

    Related Search


    XML: View XML
Show More
Show Fewer
Jump to Top of Page
https://www.fs.usda.gov/treesearch/pubs/22046