The aims of the present study are to produce bamboo fiber reinforced composite (BFRC) with high yield and to investigate the mechanical properties of BFRC comparing with those of commercial bamboo ...scrimber (BS) and laminated bamboo lumber (LBL). A novel process was developed for production of BFRC using oriented bamboo fiber mat (OBFM) made by a pilot machine. The yield and the mechanical properties of BFRC were investigated and analyzed in comparing with those of raw bamboo and other bamboo-based composites. The results show that the novel process produces 92.54% yield of OBFM due to without any chemical and special removing of inner and outer layer of bamboo during processing. In addition, all the mechanical properties and the variability of BFRC were significantly enhanced comparing with those of raw bamboo and other bamboo-based composites.
Moso bamboo (
Phyllostachys heterocycla
(
Carr
.) Mitford cv. Pubescens) was subjected to heat treatment with saturated steam at 140, 160, and 180 °C for 10–30 min to evaluate the effects of the ...treatment on the properties of bamboo. The changes in the physical, mechanical, and chemical properties as well as microscopic structures of moso bamboo were analyzed in this study. Results indicated that its equilibrium moisture content (EMC) decreased gradually after being treated by high-temperature saturated steam mostly due to the hemicelluloses’ degradation. Both the temperature and duration of treatment affect the mechanical properties of bamboo. The modulus of elasticity (MOE) of bamboo was prone to be affected by heat treatment with saturated steam as compared to the modulus of rupture (MOR). The MOR and MOE increased as compared to the control when the sample was treated at 140 °C. However, a severe treatment negatively affects the mechanical properties of bamboo. The MOR and MOE decreased by 47% and 20% as compared to the control when the sample was heated at 180 °C for 30 min.
Heat-treated wood, a relatively new product treated at high temperatures of 180–260 °C, possesses new versatile and attractive properties, which makes it popular for outdoor applications. It is of ...considerable importance to investigate the influence of sunlight on the weathering degradation processes. In order to understand the degradation processes, kiln-dried (untreated) and heat-treated (210 °C) jack pine woods (Pinus banksiana) were exposed to artificial sunlight irradiation for different periods. Before and after exposure, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using SEM, FTIR spectroscopy, and XPS. Degradation of middle lamellae, checking of cell wall and destruction of bordered pits were observed on heat-treated wood surfaces due to sunlight irradiation by SEM analyses. FTIR spectroscopy and XPS studies provided information about the behavior of functional groups of lignin during irradiation. The oxygen to carbon ratios revealed that the photo-degradation of lignin and presence of extractives played important roles in discoloration and wetting behavior of heat-treated wood surfaces during irradiation. The structural changes during irradiation also influenced wettabilty of the irradiated samples.
► Investigate the detailed color variation caused by artificial weathering of three heat-treated regional North American species due to artificial weathering with Kubelka–Munk (K–M) spectra and ...CIE-L*a*b* system. ► Chemical analysis of heat-treated wood main components during weathering. ► Identify the connection between heat-treated wood discolorations and the degradation of wood components.
Effect of artificial weathering on the wood surface color modifications of three North American species (jack pine, aspen, and birch) heat-treated under different temperatures was studied by spectrocolorimetric colormeter (datacolor, CHECK TM). Data was analyzed using the reflectance spectra (400–700nm) as well as the CIE-L*a*b* system and ΔE. Kubelka–Munk (K–M) spectra of samples were recorded as a function of artificial weathering time to obtain the absorption maxima of the chromophore woods formed during artificial weathering. The results were compared with those of the respective untreated (Kiln-dried) species. Analysis of chemical components shows that the lignin percent of jack pine, aspen, and birch increased after heat treatment (28.66–35.9%, 20.27–26.41%, and 19.04–22.71% respectively) which might be due to smaller influence of heat treatment on lignin content than hemicelluloses. This improves the resistance of heat-treated wood to photo-degradation. This is also supported by the smaller change observed in K–M spectra and total color parameters in CIE-L*a*b* system of heat-treated wood samples compared to those of untreated wood when weathered for72h. However, the lignin percent of heat-treated woods reduce to maximum 2.5% after artificial weathering of 1512h. This suggests that the weathering degrades most lignin matrix; consequently, both the colors of heat-treated woods and untreated woods are lighter and very similar after a long period of artificial weathering.
► Investigate detailed structural changes of heat-treated wood due to weathering. ► Identify connection between physical structural changes and chemical degradation. ► Study effect of heat treatment ...conditions on weathering degradation process.
Effect of artificial weathering on the surface structural changes of birch (Betule papyrifera) wood, heat-treated to different temperatures, was studied using the fluorescence microscopy and the scanning electron microscopy (SEM). Changes in the chemical structure of wood components were analyzed by FTIR in order to understand the mechanism of degradation taking place due to heat treatment and artificial weathering. The results are compared with those of the untreated (kiln-dried) birch. The SEM analysis results show that the effect of weathering on the cell wall of the untreated birch surface is more than that of heat-treated samples. The FTIR spectroscopy results indicate that lignin is the most sensitive component of heat-treated birch to the weathering degradation process. Elimination of the amorphous and highly crystallised cellulose is observed for both heat-treated and untreated wood during weathering. It is also observed that heat treatment increases the lignin and crystallised cellulose contents, which to some extent protects heat-treated birch against degradation due to weathering.
This study aimed at developing a thermo-hydro-mechanical (THM) processing to compress poplar wood and investigating the effects of high temperature, moisture, and pressure during the THM processing ...on the changes in microstructure, porosity, mechanical properties, and dimensional stability of compressed poplar wood. The variations in these properties were correlated and their mathematical relations were determined. Poplar woods with high moisture content were compressed using different pressures at a temperature of 160 °C for different periods. The compression level was characterized by the volume compression ratio (CR), which is defined as the ratio of the compression volume and the original volume of sample before and after THM processing. The obtained results indicated that the high pressure of THM process caused the collapsing of wood cell lumens and the developing of a certain amount of fractures in the cell wall. The damage level of wood cells increased with increasing pressure and time. Moreover, the pressure narrowed the cell lumens, which decreased significantly the pore volume in wood substrate. The pore size distribution shifted from the level of macropores to those of mesopores and micropores after THM process. The THM process created superior mechanical property, especially for those with higher CR. Besides, it was revealed that the process decreased dramatically the set recovery of treated woods and improved their dimensional stability. A significant improvement was achieved in terms of the mechanical and physical properties of compressed poplar wood via the structural reformation during the THM process.
The electric arc furnace (EAF) has the potential to significantly contribute to the decarbonization of the iron and steel industry. However, during EAF steelmaking, carbon still needs to be injected ...into the molten slag to initiate slag foaming, which is beneficial to the energy efficiency and protection of the furnace. To move away from fossil carbon, biocarbon has gained attention as an injection carbon agent. In this study, two biochar candidates were added to the molten slag layer of an induction furnace for steel melting, to simulate EAF steelmaking conditions. The resultant slag foaming height was measured, and a ranking in comparison to two fossil carbon candidates was developed. The results indicate that the injection biochar sample, in the form of a bio-briquette, has a considerable degree of slag foaming capacity. More work is ongoing to develop a standardized testing methodology of ranking various injection biochar candidates for their suitability and qualification for use on a larger scale.
The objective of this study is to investigate the relevance of hybrid poplar compreg density and its physical properties and surface characteristics, such as hygroscopicity, dimensional stability, ...wettability, roughness, surface energy, and porosity. The different desired densities (ranging from 0.6 to 1.2 g/cm
3
) of compreg were achieved using manufacturing processes with various parameters. The results indicated that the water absorption decreased and dimensional stability improved with the density increasing in the range of this study. In addition, the density was contributed to the reduction of the wettability and the roughness of compreg. Furthermore, the evaluation of the surface energy showed that the total surface free energy declined significantly due to the densification process. The high density reduced the apertures present in the vessels and the fiber cells and, consequently, decreased the total porosity of compreg. This, in turn, impeded the penetration of moisture into compreg and reduced its hygroscopicity.
The effects of high temperature, moisture, and mechanical action during the thermo-hydro-mechanical (THM) processing, on the changes in surface properties of poplar, namely, surface color, roughness, ...wettability, and microstructure, were investigated in this study. The correlation between observed changes in surface properties and chemical characteristics was also analyzed. Poplar woods with high moisture content were compressed using different pressures at temperature of 160 °C for four different periods. The wood surfaces became darker and smoother, and their surface free energy decreased significantly after the THM process. THM process markedly reduced surface hygroscopicity compared to the control wood. The cell lumens of THM wood became narrow with increasing compression ratio due to the enhancing high pressure. Collapse and fractures of cell walls developed during THM treatment. Furthermore, results indicated that a series of chemical reactions in different components of wood took place during THM process, such as degradation of hemicelluloses, condensation of lignin, and decomposition of extractives. In turn, these chemical modifications contributed to the darkening of color as well as the reduction of wettability and surface free energy of THM wood.
PDF
