ABSTRACT

This work focused on the upgrading of non-durable tropical wood species originating from fast-growing plantations of Costa Rica. Modification of such tropical woods with furfuryl alcohol, although has not been broadly studied up to date, offers a potential way to increase their low durability. The purpose of this research was to investigate the modification effects on cell wall, vessels wall, radial and axial parenchyma using confocal laser scanning microscopy (CLSM) as well as the changes in the bands of chemical composition using Fourier-transform infrared spectroscopy (FTIR). In fact, nine tropical wood species such as Cedrela odorata, Cordia alliodora, Enterolobium cyclocarpum, Gmelina arborea, Hieronyma alchorneoides, Samanea saman, Tectona grandis, Vochysia ferruginea and Vochysia guatemalensis were treated with plain furfuryl alcohol (FA), and furfuryl alcohol combined with silver nanoparticles (FA-NPsAg). Furfurylation effects were also assessed by the weight percentage gain (WPG) of wood. Results showed that WPG varied from 14.4% to 44.3% with the FA treatment, and from 12.9% to 44.5% with the FA-NPsAg treatment. In the species which exhibited a WPG over 25% with the FA treatment, fluorescence at 600 nm band occurred mostly in the cell walls of fibres, while the furfurylation degree in radial and axial parenchyma was limited. Moreover, furfurylation occurred in lesser extent in wood species with high abundance of axial parenchyma as revealed by fluorescence. Wood species such as Vochysia ferruginea, Vochysia guatemalensis, Cedrela odorata, Samanea saman, Enterolobium cyclocarpum, which showed WPGs>25%, evidenced considerable changes in the lignin structure as observed in the FTIR spectra. In particular, with the FA treatment, the changes were observed in the bands of 1711, 1652, 1561, 889, 796 and 733 cm^–1, whereas, with the FA-NPsAg treatment, the changes occurred in the bands of 1711, 1505, 1426, 1370, 1224 and 1016 cm^–1. Overall, no significant difference was found in FTIR spectra and anatomical fluorescence between the FA and FA-NPsAg treatment, probably because the NPsAg concentration was insufficient for a change to occur in the bonds.

摘要

这项工作的重点是升级源自哥斯达黎加速生种植园的非耐用热带木材品种。用糠醇对这种热带木材进行改性，虽然迄今为止尚未得到广泛研究，但提供了一种提高其低耐久性的潜在方法。本研究的目的是使用共聚焦激光扫描显微镜 (CLSM) 研究对细胞壁、血管壁、径向和轴向薄壁组织的修饰效果，以及使用傅里叶变换红外光谱 (FTIR) 研究化学成分波段的变化. 事实上，九种热带木材品种，如雪松、Cordia alliodora 、 Enterolobium cyclocarpum、Gmelina arborea，Hieronyma alchorneoides、Samanea saman、Tectona grandis、Vochysia ferruginea和Vochysia guatemalensis分别用普通糠醇 (FA) 和糠醇与银纳米粒子 (FA-NPsAg) 结合处理。还通过木材的重量百分比增加 (WPG) 评估了糠基化效应。结果显示，FA 治疗的 WPG 从 14.4% 到 44.3% 不等，FA-NPsAg 治疗的 WPG 从 12.9% 到 44.5% 不等。在FA处理后WPG超过25%的物种中，600 nm波段的荧光主要出现在纤维的细胞壁中，而径向和轴向薄壁组织的糠基化程度有限。此外，荧光显示，在轴向薄壁组织丰度高的木材品种中，糠酰化发生的程度较低。木种，例如Vochysia ferruginea、Vochysia guatemalensis、Cedrela odorata、Samanea saman、Enterolobium cyclocarpum, 显示 WPGs > 25%, 证明了在 FTIR 光谱中观察到的木质素结构的相当大的变化。特别是，在 FA 处理下，变化发生在 1711、1652、1561、889、796 和 733 cm ^–1的条带中，而在 FA-NPsAg 处理下，变化发生在 1711、1505 的条带中, 1426, 1370, 1224 和 1016 厘米^–1。总体而言，FA 和 FA-NPsAg 处理之间的 FTIR 光谱和解剖荧光没有发现显着差异，可能是因为 NPsAg 浓度不足以使键发生变化。