Properties of Thermally Modified Southern Pine Wood Pretreated with Alkylalkoxysilanes

Abstract

The alkyl-alkoxysilane (AAS) pre-impregnation method and thermal modification were combined to improve the water-related properties of southern yellow pine (Pinus spp.) sapwood. Four types of AAS with varied alkyl chain lengths, including butyltrimethoxysilane (BTMOS), octyltrimethoxysilane (OTMOS), dodecyltrimethoxysilane (DTMOS), and cetyltrimethoxysilane (CTMOS), were used to pre-impregnate wood samples at a concentration of 5% or 15% mass fraction, and the subsequent thermal modification was processed at either 180 °C or 200 °C. The water absorption, dimensional stability, equilibrium moisture content (EMC), mechanical properties (modulus of rupture (MOR), and modulus of elasticity (MOE)), and mold resistance of the treated wood were evaluated. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to reveal the mechanism of the combined treatments in improving the properties of wood. Compared with thermal modification alone, the AAS combined treatment improved the water repellency, mechanical properties, and mold resistance of the modified wood. The study also identified the penetration of AAS into the wood cell wall and its reaction with the chemical components of the cell wall.

Siloxane-Starch-Based Hydrophobic Coating for Multiple Recyclable Cellulosic Materials

“…Of these signals, only the one at 1034 cm −1 may be evidence of the covalent bonding of silanol condensation products to the hydroxyl groups of cellulose and starch. The others prove that the organosilicon material has deposited on the paper surface but is not necessarily covalently bound with it [ 17 , 26 ]. This is complicated by the fact that some of these key signals overlap with the cellulose and starch spectra.…”

“…Most of them are based on reactive aminosilanes [ 8 ] or chlorosilanes [ 9 , 16 ] in organic solvents, which rapidly condense with water, releasing harmful by-products into the environment; therefore, their application in the highly humid environment of paper machines seems to be impossible. The most promising agents are those based on alkoxysilanes [ 13 , 17 ]. Their condensation with water results in relatively harmless aliphatic alcohols as side products, and the progress and equilibrium of this reaction can be controlled by pH buffers and the relative concentration of di-, tri-, and mono functional silanes [ 18 ].…”

Resistance of Scots pine (Pinus sylvestris L.) after treatment with caffeine and thermal modification against Aspergillus niger

“…or other mould species. Works by Ahola et al (2002) and Chen et al (2016) revealed that there is no difference in fungal growth between thermally modified wood and untreated wood tested. Further studies by Gobakken and Lebow (2010) showed that thermally modified Scots pine acts similarly to non-modified Scots pine sapwood against fungal attack.…”

“…Similarly to previous works, control samples after thermal modification were covered with the mycelia of the A. niger rapidly. In the work of Chen et al (2016), A. niger mycelium covered about 75% of the surface of modified Southern pine sapwood at 180 °C to 200 °C. A similar phenomenon was noticed in the studies by Yilgör and Nami Kartal (2010).…”

INFLUENCE OF COMMERCIAL THERMAL TREATMENT ON Eucalyptus grandis Hill ex Maiden WOOD PROPERTIES

“…Wood thermally treated can be described as a physical-chemical process that change wood anatomy and wood constituents, such cellulose, hemicellulose, lignin and extractives, performing this process under temperature varying between 150 and 280 °C on controlled atmosphere, which can be vacuum, steam or under heated oil (Batista et al, 2016b;Lee et al, 2018;Wikberg and Maunu, 2004), and for a controlled time, improving physical properties reducing shrinkage, permeability and hygroscopicity, increasing dimensional stability (Barboutis and Kamperido, 2019;Batista et al, 2018;Ribeiro et al, 2019). Otherwise, with wood constituents degradation, such as cellulose and hemicellulose, mechanical properties are reduced proportionally with thermal treatment (Chen et al, 2016;Kariz et al, 2016;Kubovský et al, 2020;Lahtela and Kärki, 2014).…”