Elrhayam Youssef, El Bachiri Abderrahim
Laboratory of Advanced Materials and Process Engineering, Department of Chemistry, Faculty of Sciences, Ibn Tofaïl University, B.P. 14000, Kenitra, Morroco; Laboratory of Organic Chemistry, Catalysis and Environment, Department of Chemistry, Faculty of Sciences, Ibn Tofaïl University, B.P. 14000, Kenitra, Morroco.
University Department, Royal Naval School of Marine Engineering - Boulevard Sour Jdid Casablanca, Morocco.
Spectrochim Acta A Mol Biomol Spectrosc. 2024 Nov 15;321:124576. doi: 10.1016/j.saa.2024.124576. Epub 2024 Jun 4.
This study describes the effect of heat treatment on some physical, chemical, and mechanical properties of Eucalyptus Camaldulensis (EC) wood at different temperatures and treatment times (200 °C-260 °C for 5, 60, and 90 min). The evaluation of hygroscopic properties was determined by relative humidity, mass loss, dimensional stability tests, and density. The results showed that the heat treatment leads to an increase in mass loss of 5.2 %-11.9 % at 200 °C. The density changed significantly for this studied species as well as the dimensional stabilization. Chemical changes in wood structure were assessed by Fourier Transform Infrared Spectroscopy.To verify the validity of the superposition "Mass loss-Density-water absorption" on the mechanical properties (modulus of elasticity (MOE) and modulus of rupture (MOR)) during heat treatment, we have developed a mathematical model based on Multiple Linear Regression (MLR), in order to establish a relationship between the independent parameters and the dependent parameters (MOE and MOR). The evaluation of the quality of the models developed was based on several statistical tools, namely R = 0.99, R = 0.99, R = 0.98, and F = 132.33. The results demonstrated that elaborate models of mechanical properties have a high predictive capacity (MOR and MOE). The wood's carbohydrates (particularly hemicelluloses) are then degraded during the heat treatment. The % of carbon increases from 47.8 to 49.8 %, which is proportional to mass loss, while the % of oxygen decreases by 46.1 %, which is inversely proportional to mass loss. Furthermore, FTIR analysis revealed that the effect of heat-treated wood chemical changes was related to the hydroxyl OH function of cellulose, functional groups, and aromatic system of lignin. In conclusion, the results demonstrated that at 200 °C, heat treatment caused a 5.2-11.9 % increase in mass loss; dimensional stability and density underwent considerable changes. FTIR spectroscopy confirmed the chemical changes in the wood structure during heat treatment. Furthermore, the "MLR" mathematical model showed that density contributed to the increase in MOR and MOE properties, while water absorption and mass loss contributed to the decrease in MOR and MOE properties. Finally, the % of oxygen decreased by 46.1 %, which is inversely proportional to the loss of mass, and the % of carbon increased from 47.8 % to 49.8 %, which is proportional to the loss of mass.
本研究描述了在不同温度和处理时间（200℃ - 260℃，处理5、60和90分钟）下，热处理对赤桉（EC）木材的一些物理、化学和机械性能的影响。通过相对湿度、质量损失、尺寸稳定性测试和密度来评估吸湿性能。结果表明，在200℃时，热处理导致质量损失增加5.2% - 11.9%。对于该研究的树种，密度以及尺寸稳定性都发生了显著变化。通过傅里叶变换红外光谱法评估木材结构中的化学变化。为了验证在热处理过程中“质量损失 - 密度 - 吸水率”叠加对机械性能（弹性模量（MOE）和抗弯强度（MOR））的有效性，我们基于多元线性回归（MLR）开发了一个数学模型，以便建立独立参数与因变量参数（MOE和MOR）之间的关系。基于几种统计工具对所开发模型的质量进行评估，即R = 0.99、R = 0.99、R = 0.98和F = 132.33。结果表明，精心构建的机械性能模型具有较高的预测能力（MOR和MOE）。木材中的碳水化合物（特别是半纤维素）在热处理过程中会降解。碳的百分比从47.8%增加到49.8%，这与质量损失成正比，而氧的百分比下降了46.1%，这与质量损失成反比。此外，傅里叶变换红外光谱分析表明，热处理引起的木材化学变化的影响与纤维素的羟基OH官能团、官能团以及木质素的芳香体系有关。总之，结果表明在200℃时，热处理导致质量损失增加5.2% - 11.9%；尺寸稳定性和密度发生了相当大的变化。傅里叶变换红外光谱证实了热处理过程中木材结构的化学变化。此外，“MLR”数学模型表明，密度有助于提高MOR和MOE性能，而吸水率和质量损失则导致MOR和MOE性能下降。最后，氧的百分比下降了46.1%，这与质量损失成反比，碳的百分比从47.8%增加到49.8%，这与质量损失成正比。
