Oxidation characteristics of chars generated from wood impregnated with (NH₄)₂HPO₄ and (NH₄)₂SO₄

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• 作者：Carmen Branca ; Colomba Di Blasi
• 关键词：Wood ; Flame retardants ; Char reactivity ; Reaction mechanisms ; Combustion
• 刊名：Thermochimica Acta
• 出版年：2007
• 期刊代码：110_00406031
• 类别：ch
• 出版时间：15 May 2007
• 卷：456
• 期：2
• 页码：120-127
• 文件大小：1852 K

摘要

Thermogravimetric analysis (heating rates between 5 and 15 K/min up to 873 K) has been carried out in air of chars, generated from the pyrolysis of wood and wood impregnated with (NH₄)₂HPO₄ and (NH₄)₂SO₄ (5%, dry wood basis) which are widely used as flame retardants. Salts significantly alter the char reactivity, but a mechanism consisting of three parallel reactions always provides a good description of the measurements. The estimated activation energy and reaction order of the most important combustion reaction, which causes the release of about 71–80%of the volatile matter, are nearly the same for untreated and (NH₄)₂SO₄ impregnated samples (about 190–200 kJ/mol and 0.86). A lower activation energy (about 150 kJ/mol) and a higher reaction order (1.35) are obtained for (NH₄)₂HPO₄ treatments. Scanning electronic microscope (SEM) images show significant modifications in the morphological structure of both wood and char as a consequence of salt impregnation.