Chemical changes induced in Pinus radiata and Eucalyptus nitens following the densification process

Densification of wood leads to improvement of its mechanical properties. Specimens of Pinus radiata and Eucalyptus nitens wood were densified using heat, steam, and pressure to improve their mechanical properties and thus enhance their utilization. At a maximum steam pressure of 550 kPa and a maximum press hydraulic pressure ranging from 4.5 to 9 MPa, selected temperatures of 160°C, 180°C, and 200°C were used to check the mechanical properties and to identify the chemical composition of wood samples before and after densification. Densified wood samples showed markedly reduced hygroscopicity. The chemical changes in the wood constituents occurring during densification were characterized using FT-IR, Py-GC/MS, and XPS. According to the densification process between pine and eucalyptus, the results obtained showed that the densification effects were better for Eucalyptus nitens than for Pinus radiata. The FT-IR analysis revealed a high condensation index for pine lignin and the low condensation index for eucalyptus lignin, indicating easier formation of C-C linkages by densification in pine lignin. Py-GC/MS analyses were performed to follow the lignin/carbohydrate ratio, and these revealed major carbohydrate losses during densification at the highest temperature

Study of Organosolv Lignins as Adhesives in Wood Panel Production

Organosolv lignins obtained from sugar maple bark and wood were studied as adhesives for wood particleboard production. Organosolv pulping of sugar maple wood and bark was carried out in the presence of Lewis acid FeCl3 as a catalyst. The organosolv lignins recovered from this process were investigated by determination of Klason plus acid-soluble lignin content, of sugars by HPLC analysis, and of ash content. Structural characterizations of these lignins were performed by Fourier-transform infrared (FT-IR) and by 31P NMR. The results of the latter studies indicate that the content of free phenolic groups was more important in bark than in wood lignin. The gel permeation chromatography (GPC) analyses results suggested that the weight-average molecular mass of wood lignin was higher than that of bark lignin. The studied organosolv lignins were used for the preparation of particleboards as recovered and in combination with glyoxal or isocyanate. It was found that sugar maple bark lignin, as such or modified with isocyanate, was a more efficient adhesive than its wood counterpart. On the contrary, it was the organosolv wood lignin combined with glyoxal which was a more efficient adhesive than its bark counterpart. In combination with isocyanate, it was the sugar maple bark organosolv lignin which was determined to have the best adhesive performance of all studied lignins

Transformation of Sugar Maple Bark through Catalytic Organosolv Pulping

The catalytic organosolv pulping of sugar maple bark was performed adopting the concept of forest biorefinery in order to transform bark into several valuable products. Our organosolv process, consisting of pre-extracting the lignocellulosic material followed by pulping with ferric chloride as a catalyst, was applied to sugar maple bark. The pre-extraction step has yielded a mixture of phenolic extractives, applicable as antioxidants. The organosolv pulping of extractives-free sugar maple bark yielded a solid cellulosic pulp (42.3%) and a black liquor containing solubilized bark lignin (24.1%) and products of sugars transformation (22.9% of hemicelluloses), mainly represented by furfural (0.35%) and 5-hydroxymethyl furfural (HMF, 0.74%). The bark cellulosic pulp was determined to be mainly constituted of glucose, with a high residual lignin content, probably related to the protein content of the original bark (containing cambium tissue). The biorefinery approach to the transformation of a solid bark residue into valuable biopolymers (lignin and cellulose) along with phenolic antioxidants from pre-extraction and the HMF derivatives from black liquor (applicable for 2,5-diformylfuran production) is an example of a catalytic process reposing on sustainable engineering and green chemistry concepts

Synthèse d'analogues cinnamiques (inhibiteurs potentiels contre mycobacterium tuberculosis)

TOULOUSE3-BU Sciences (315552104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Effect of Wood Welding Treatment on Chemical Constituents of Australian Eucalyptus species

Introduction: The potential of wood welding as a fast and cost-effective alternative to gluing for Australian hardwood species has been demonstrated in recent studies (Belleville et al. 2016, 2017). The technique consists in assembling solid wood pieces by mechanical friction to generate heat, which induces the thermochemical changes in lignin which lead to wood welding. The results so far confirm the importance of density and occurrence of anatomical features in the weld line strength and consequently the definition of optimal welding parameter (Leban et al. 2005; Properzi et al. 2005; Belleville et al. 2016). Polymeric material and other compounds present in woods studied previously have commonly been identified to explain observed differences between Canadian wood species (Rodriguez et al. 2010; Sun et al. 2010; Belleville et al. 2013, 2016)