Impact of thermal modification combined with silicon compounds treatment on wood structure

In the present study silicon containing formulations were investigated for their applicability in solid wood modification. Black pine sapwood was thermally modified at 180oC and 200oC (3, 5 and 7 hours) and afterwards, an additional chemical treatment with silicon containing systems (N-2-aminoethyl-3-aminopropyltrimethoxysilane) followed, in an attempt to invigorate hydrophobicity and durability of wood. Infrared spectroscopy (FTIR) was used to examine the formation of new bonds in the treated materials and atomic absorption spectrometry (AAS) to measure the silane concentration. The results showed a high reactivity between thermally modified wood and organosilicon compounds. The presence of bands representing vibrations of the Si–O–CH3 group in IR spectra of modified wood and after extraction confirms the stable character of the formed bonds between the hydroxyl group of wood and the methoxy groups of organosilanes. Furthermore, reactivity between wood and AE-APTMOS and alkyd resin solution was confirmed by the AAS results. Alkyd resin caused a higher concentration of silica in wood mass, which increases as the thermal treatment temperature increases. The organosilicon compounds caused a much higher resistance to water washout, revealing permanent binding of silanes to wood mass.

Comparative study of wood color stability using accelerated weathering process and infrared spectroscopy

The objective of this study was to investigate effects of artificial weathering on color stability of six tropical wood species: Apuleia leiocarpa (Vog.) Macbride, Bagassa guianensis Aubl., Dipteryx odorata (Aubl.) Wild., Hymenea courbaril/Linn., Manilkara bidentata A. Chev., Tabebuia sp. Chemical composition of weathered wood was also studied by FT-IR spectra. With the progressive artificial weathering color of wood changed gradually. Hymenea courbaril Linn. wood occurred the greatest range of the total color change. The largest changes in intensity of the wood color took place at the beginning of artificial weathering process. FT-IR analysis indicated the occurrence of lignin and hemicellulose oxidative changes resulting in formation of carbonyl and carboxyl compounds during weathering. Oxidation products are the main cause of wood surface discoloration. Additionally, changes suggesting depolymerisation of cellulose were identified as well.

Characterizations and properties of torrefied Quercus variabilis cork

The energy properties and physicochemical structure of torrefied Quercus variabilis cork were investigated with torrefaction between 150°C and 300°C in a tubular furnace. The mass yield, energy yield, and physicochemical properties of torrefied cork were characterized via proximate analysis, elemental analysis, colour analysis, and scanning electron microscope. The results showed that volatiles, moisture content, and the ratios of oxygen to carbon and hydrogen to carbon decreased with increasing torrefaction temperature. Ash content and fixed carbon content increased with increasing temperature, and the enhanced fixed carbon content resulted in the increase of high heating value (HHV) of cork. The HHV compared to untreated cork increased by around 16% after torrefaction at 300°C for 1h. With increasing torrefaction temperature, the cell cavity increased in size, the corrugation was less deformed, and less sediment appeared on cell walls. In conclusion, torrefaction improved both the energy and physicochemical properties of cork. In addition, FTIR and CP/MAS 13C NMR spectra analysis showed that polysaccharide degraded at 200°C, and lignin degraded between 250 and 300°C. Although suberin had better thermal resistance, its NMR signal intensity decreased after torrefaction at 300°C.

Characteristics of nontoxic bamboo bioboard by melamine and cellulose adhesive

In this research, the influence of various factors on the performance of the melamine bamboo cellulose gum is investigated by orthogonal test method, with the pressing temperature, pressing time, the added amount of cellulose gum, melamine dosage as factors. And analyze the samples by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), DTG, etc. The amount of melamine is the main factor affecting the quality of bamboo composite material and its physical and mechanical properties, it has a significant impact on MOR board, internal bond strength, elastic modulus and other properties; cellulose gum is a secondary factor affecting performance. The results showed that cellulose gum ratio of 5 %, ratio of melamine of 2.5 % and the hot press time of 9 min provided the optimum conditions for hot press.

Study of the discoloration behaviour of teak wood (Tectona grandis Linn. fil.) caused by simulated sunlight

To investigate the discoloration behaviour of teak (Tectona grandis Linn. fil.) during irradiation, teak veneer specimens were exposed to xenon lamp light simulating sunlight for 80 h and subsequently analysed with a colorimeter. The colour changes were explained by recording Fourier transform infrared (FTIR) and gas chromatography-mass spectrometry (GC-MS) spectra at different exposure times. Forty hours of simulated irradiation marked a key point in the colorimetric analysis. During irradiation of 40 h, the increase in the CIELAB parameters ∆a* and ∆b* originated from the generation of carbonyl derivatives that were determined by FTIR analysis. Besides that, by combining GC-MS and microscopic analyses, the decrease in ∆L* in the first 20 h resulted from extractives migrating from the interior to the surface, and that the subsequent increase in ∆L* mainly arose from volatilization of the extractives. Additionally, the decrease in ∆b* after another 40 h of irradiation was mainly due to decreasing volatile extractive contents. Our conclusion reveals the causes of photo-induced discoloration in teak.

Changes in gross calorific value of thermally treated scots pine (Pinus Sylvestris L.) and sessile oak (Quercus Petraea L.) wood and their explanation using ftir spectroscopy

Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea L.) wood were thermally treated in an oven at the temperatures of 160°C, and 200°C under atmospheric pressure in the presence of air for 3 and 9 hrs. The mass loss and gross calorific value were determined. Non-treated wood samples achieved a gross calorific value of 22 193 J.g-1 for pine wood and 19 277 J.g-1 for oak wood. Whereas the calorific value of pine wood with increasing severity of treatment decreased, in the case of oak it increased. The mass loss increased with increasing treatment severity by both wood species. Mentioned differences in pine and oak wood behaviour using ATR-FTIR spectroscopy were explained. In the case of pine wood with increasing temperature and time of exposure a decrease of resin acids was observed. This may be contributed to decrease in GCV. In the case of oak wood, mainly at temperature of 200°C the degradation of hemicelluloses was observed that results in relative increasing in the lignin content with followed increase in the GCV.