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Acetylation of tropical hardwood species from forest plantations in Costa Rica: an FTIR spectroscopic analysis
Journal of Wood Science ( IF 2.9 ) Pub Date : 2020-07-16 , DOI: 10.1186/s10086-020-01898-9
Johanna Gaitán-Alvarez , Alexander Berrocal , George I. Mantanis , Róger Moya , Fabio Araya

Acetylation of softwoods has been largely investigated to increase the dimensional stability and biological resistance of wood. However, the knowledge of this technology has not been applied to tropical hardwood species up to date. The objective of this work was to study the effect of acetylation on nine tropical hardwood species, from forest plantations in Costa Rica, by applying acetic anhydride in three different treatment times (1 h, 2.5 h, 4 h), as well as to evaluate this by Fourier-Transform Infrared Spectroscopy (FTIR). Results showed that weight percentage gain (WPG) of wood varied from 2.2 to 16.8%, with Vochysia ferruginea species showing the highest WPG, and Gmelina arborea and Tectona grandis species exhibiting the lowest WPGs. Tropical woods such as Enterolobium cyclocarpum, Hieronyma alchorneoides and Samanea saman exhibited statistical differences among treatment times, whereas the rest of the species studied showed no significant differences. In general, the most effective acetylation time was 2.5 h for all the species. The ratio of intensity (RI) from the FTIR spectra was greater at the 1732 cm−1, 1372 cm−1 and 1228 cm−1 peaks for all tropical species, associated with lignin. A good correlation between the RI of those peaks and WPG was found; the same was also found between all RIs and each other. Meanwhile, RI associated to the hemicelluloses and lignin (1592 cm−1 and 1034 cm−1 peaks, respectively) showed no correlation with WPG, nor between each other or with the other RIs. Furthermore, it was suggested that RI at 1732 cm−1 (associated to acetyl groups C=O) can be considered as a reliable indicator of the degree of acetylation for tropical hardwood species. Finally, it was observed that tropical hardwoods having more suitable anatomical features, like larger vessel diameter, higher ray width and frequency, and lesser deposits such as gums and tyloses in the vessels, resulted in significantly higher WPGs.

中文翻译:

哥斯达黎加森林人工林中热带硬木树种的乙酰化:FTIR光谱分析

大量研究了软木的乙酰化以增加木材的尺寸稳定性和生物抗性。但是,迄今为止,该技术的知识尚未应用于热带硬木树种。这项工作的目的是通过在三个不同的处理时间(1小时,2.5小时,4小时)中使用乙酸酐,研究乙酰化对哥斯达黎加人工林的9种热带硬木树种的影响,并评估这是通过傅立叶变换红外光谱(FTIR)实现的。结果表明,木材的增重百分比(WPG)从2.2到16.8%不等,其中短木(Vochysia ferruginea)品种的WPG最高,而Gmelina arborea和Tectona grandis品种的WPG最低。热带木材,如Enterolobium cyclocarpum,Hieronyma alchorneoides和Samanea saman在处理时间之间显示出统计学差异,而其余研究物种则没有显着差异。通常,所有物种的最有效乙酰化时间为2.5小时。FTIR光谱的强度比(RI)在与木质素有关的所有热带物种的1732 cm-1、1372 cm-1和1228 cm-1峰处更大。发现这些峰的RI与WPG之间具有良好的相关性;在所有RI之间也发现了相同的情况。同时,与半纤维素和木质素相关的RI(分别为1592 cm-1和1034 cm-1峰)与WPG,彼此之间或与其他RI之间均无相关性。此外,有人建议将1732 cm-1处的RI(与乙酰基C = O相关)视为热带硬木树种乙酰化程度的可靠指标。最后,观察到热带硬木具有更合适的解剖特征,例如较大的容器直径,较高的射线宽度和频率以及较小的沉积物(例如容器中的树胶和酪醇),导致WPG明显较高。
更新日期:2020-07-16
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