scholarly journals Effects of aluminum sulfate soaking pretreatment on dimensional stability and thermostability of heat-treated wood

2020 ◽  
Author(s):  
Lijie Qu ◽  
Zhenyu Wang ◽  
Jing Qian ◽  
Zhengbin He ◽  
Songlin Yi
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Changes ◽  
Aluminum Sulfate ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Chinese Fir ◽  
Heat Treated ◽  
Thermal Stability Of

Abstract Acidic aluminum sulfate hydrolysis solutions can be used to catalyze the thermal degradation of wood in a mild temperature environment, and thus reduce the temperature required for heat treatment process. To improve the dimensional and thermal stability of Chinese fir during heat treatment at 120 °C, 140 °C and 160 °C, this study investigated the effects of soaking pretreatment with 5%, 10% and 15% aluminum sulfate on the chemical and structural changes of the heat-treated Chinese fir. The results indicated that the samples treated at 15% aluminum sulfate concentration and 160 °C heat treatment achieved the best dimensional and thermal stability. Chemical analyses by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the catalysis of aluminum sulfate resulted in degradation of hemicelluloses during the heat treatment, and an increase in the soaking concentration and heat treatment temperature also affected the thermal degradation of celluloses. The scanning electron microscope (SEM) and mass changes test results proved that the hydrolyzed aluminum flocs mainly adhered to the inner wall of the wood tracheid as spherical precipitates, and when the soaking concentration reached 10% and 15%, a uniform soaking effect could be achieved. The thermogravimetric (TG) analysis revealed the soaking pretreatment effectively improved the thermal stability of the heat-treated wood by physically wrapping and promoting the formation of a carbon layer on the wood surface during heat treatment. Thus, aluminum sulfate soaking pretreatment exerted a great effect on the dimensional and thermal stability of wood, allowing heat treatment to be performed at a lower temperature.

Thermal Degradation Study of Functionalized MWNT Reinforced Segmented Polyurethane Membrane

2006 ◽  
Vol 38 (3) ◽  
pp. 261-271 ◽  
Author(s):  
S. Mondal ◽  
J. L. Hu
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Nitrogen Atmosphere ◽  
Segmented Polyurethane ◽  
Degradation Study ◽  
Heat Treated ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Thermal Stability Of ◽  
Mwnt Content

The thermal degradation of polytetramethylene glycol (PTMG, Mn 1/42900) based polyurethane (PU), along with four different weight contents (such as 0.25, 0.50, 1.0, and 2.5 wt%) of functionalized multiwalled nanotube (MWNT) reinforced PUs are studied in air as well as in nitrogen atmosphere. The degradation results are reported in 10 and 50% weight loss and derivative of thermogravimetry (DTG). As expected, PUs are thermally more stable in nitrogen than in air. However, the influence of MWNT content on thermal stability is unclear. At 0.25 and 0.50 wt% of MWNT content, thermal stability declined and a further increase of MWNT improved the thermal stability of PU. Fourier-transform infrared (FTIR) analysis is also performed for untreated and heat treated films in order to understand the degradation at different temperatures. Free C1/4O stretching neck dimension increases with increasing temperature which signifies breaking of H-bonding detected by FTIR measure ments.

scholarly journals Optimization of the Solidification Method of High-Level Waste for Increasing the Thermal Stability of the Magnesium Potassium Phosphate Compound

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3789
Author(s):  
Svetlana A. Kulikova ◽  
Sergey S. Danilov ◽  
Kseniya Yu. Belova ◽  
Anastasiya A. Rodionova ◽  
Sergey E. Vinokurov
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Compressive Strength ◽  
Potassium Phosphate ◽  
Treatment Temperature ◽  
High Level Waste ◽  
Leaching Rate ◽  
High Level ◽  
The Impact ◽  
Thermal Stability Of

The key task in the solidification of high-level waste (HLW) into a magnesium potassium phosphate (MPP) compound is the immobilization of mobile cesium isotopes, the activity of which provides the main contribution to the total HLW activity. In addition, the obtained compound containing heat-generating radionuclides can be significantly heated, which increases the necessity of its thermal stability. The current work is aimed at assessing the impact of various methodological approaches to HLW solidification on the thermal stability of the MPP compound, which is evaluated by the mechanical strength of the compound and its resistance to cesium leaching. High-salt surrogate HLW solution (S-HLW) used in the investigation was prepared for solidification by adding sorbents of various types binding at least 93% of 137Cs: ferrocyanide K-Ni (FKN), natural zeolite (NZ), synthetic zeolite Na-mordenite (MOR), and silicotungstic acid (STA). Prepared S-HLW was solidified into the MPP compound. Wollastonite (W) and NZ as fillers were added to the compound composition in the case of using FKN and STA, respectively. It was found that heat treatment up to 450 °C of the compound containing FKN and W (MPP-FKN-W) almost did not affect its compressive strength (about 12–19 МPa), and it led to a decrease of high compressive strength (40–50 MPa) of the compounds containing NZ, MOR, and STA (MPP-NZ, MPP-MOR, and MPP-STA-NZ, respectively) by an average of 2–3 times. It was shown that the differential leaching rate of 137Cs on the 28th day from MPP-FKN-W after heating to 250 °C was 5.3 × 10−6 g/(cm2∙day), however, at a higher temperature, it increased by 20 and more times. The differential leaching rate of 137Cs from MPP-NZ, MPP-MOR, and MPP-STA-NZ had values of (2.9–11) × 10−5 g/(cm2∙day), while the dependence on the heat treatment temperature of the compound was negligible.

scholarly journals Haptic and Aesthetic Properties of Heat-Treated Modified Birch Wood

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1081
Author(s):  
Vlastimil Borůvka ◽  
Přemysl Šedivka ◽  
David Novák ◽  
Tomáš Holeček ◽  
Jiří Turek
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Heat Capacity ◽  
Moisture Content ◽  
Thermal Characteristics ◽  
Treated Wood ◽  
Treatment Temperature ◽  
Birch Wood ◽  
Positive Perception ◽  
Heat Treated

This paper deals with the effect of heat treatment on the selected physical properties of birch wood. Five stages of heat treatment were used, ranging from 160 °C to 200 °C, in 10 °C increments, having a peak treatment duration of 3 h for each level. Primarily, changes in thermal characteristics, namely conductivity, diffusivity, effusivity, volume heat capacity, changes in colour and gloss parameters, mass loss due to modification and different moisture content in wood under given equilibrium climatic conditions, were monitored. The ISOMET 2114 analyser was used to measure the thermal characteristics. The measurement principle of this analyser is based on the analysis of the thermal response of the analysed material to pulses of heat flow. Measurements of colour, gloss, density and moisture content were carried out according to harmonised EN standards. The aim was to experimentally verify the more or less generally known more positive perception of heat-treated wood, both by touch and sight, i.e., the warmer perception of darker brown shades of wood. In terms of thermal characteristics, the most interesting result is that they gradually decrease with increasing treatment temperature. For example, at the highest treatment temperature of 200 °C, there is a decrease in thermal conductivity by 20.2%, a decrease in volume heat capacity by 15.0%, and a decrease in effusivity by 17.7%. The decrease in thermal conductivity is nearly constant at all treatment levels, specifically at this treatment temperature, by 6.0%. The fact mentioned above is positive in terms of the tactile perception of such treated wood, which can have a positive effect, for example, in furniture with surface application of heat-treated veneers, which are perceived positively by the majority of the human population visually or as a cladding material in saunas. In this context, it has been found that the thermal modification at the above-mentioned treatment temperature of 200 °C results in a decrease in brightness by 44.0%, a decrease in total colour difference by 38.4%, and a decrease in gloss (at an angle of 60°) by 18.2%. The decrease in gloss is only one essential negative aspect that can be addressed by subsequent surface treatment. During the heat treatment, there is also a loss of mass in volume, e.g., at a treatment temperature of 200 °C and subsequent conditioning to an equilibrium moisture content in a conditioning chamber with an air temperature of 20 ± 2 °C and relative humidity of 65 % ± 5%, there was a decrease by 7.9%. In conclusion, the experiments clearly confirmed the hypothesis of a positive perception of heat-treated wood in terms of haptics and aesthetics.

Study on the Longitudinal Tensile Strength of Tracheids of Heat-Treated Wood

2011 ◽  
Vol 183-185 ◽  
pp. 1896-1900
Author(s):  
Rong Jun Zhao ◽  
Xian Bao Cheng ◽  
Wei Wei Shuangguan ◽  
Juan Sun ◽  
Ben Hua Fei
Keyword(s):  
Heat Treatment ◽  
Treated Wood ◽  
Chinese Fir ◽  
Chemical Components ◽  
Cellulose Crystallinity ◽  
Cell Level ◽  
Masson Pine ◽  
Longitudinal Tensile Strength ◽  
Heat Treated ◽  
Relationship Of

In this paper, the zero-span tensile strengths of tracheids of Chinese fir and Masson pine were investigated, and the effect of the moisture on the tracheid strength was also discussed. Furthermore, the influence of thermal treatment on the zero-span tensile strengths of tracheids were analysed, and research of relationship of zero-span tensile strengths, chemical components and cellulose crystallinity were also conducted. This study tried to explore the inherent mechanism of heat treatment on the cell level.

Thermal Stability of Cu and Cu2O Nanoparticles in a Polyimide Film

2008 ◽  
Vol 8 (9) ◽  
pp. 4822-4825 ◽  
Author(s):  
Jae-Youn Choi ◽  
Wenguo Dong ◽  
Dong Joo Choi ◽  
Chong S. Yoon ◽  
Young-Ho Kim
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Polyimide Film ◽  
Cu Nanoparticles ◽  
Transmission Electron ◽  
Heat Treated ◽  
Cu Film ◽  
Vis Spectroscopy ◽  
Cu2o Nanoparticles ◽  
Thermal Stability Of

Nanoparticles of Cu or Cu oxide dispersed in a polyimide (PI) film were fabricated by reaction of polyamic acid with a thin Cu film during imidization. In this paper, the thermal stability of the Cu or Cu oxide nanoparticles was investigated under various atmospheres. The PI/nanoparticle composites were heat-treated at 140 °C and 250 °C in air, N2, Ar, and 5% H2 atmospheres. Nanoparticles in the PI film were characterized by UV-VIS spectroscopy and transmission electron microscopy. The optical absorption peaks originating from Cu or Cu2O nanoparticles were changed by heat-treatment in different atmospheres. When Cu nanoparticles were oxidized by heat-treatment in air, the surface plasmon resonance (SPR) peak originating from the Cu nanoparticles disappeared. The quantum confined absorption peak of Cu2O was not affected by heat-treatment in N2 or Ar. Cu2O nanoparticles were reduced by heat-treatment at 250 °C in 5% H2 atmosphere and a new SPR peak appeared. Our results show that Cu nanoparticles are easily oxidized and highly dense Cu nanoparticles can be formed by reducing Cu2O nanoparticles.

Microstructure and Phase Composition of Iridium Coating on Molybdenum after Heat Treatment at 1400°C

2011 ◽  
Vol 189-193 ◽  
pp. 688-691 ◽  
Author(s):  
Wang Ping Wu ◽  
Zhao Feng Chen ◽  
Xin Lin
Keyword(s):  
Phase Transition ◽  
Heat Treatment ◽  
Thermal Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface And Interface ◽  
Heat Treated ◽  
Glow Plasma ◽  
Ar Gas ◽  
Thermal Stability Of

Iridium (Ir) could be taken as high temperature protective coating for the refractory metals. Ir coating was deposited on the surface of molybdenum (Mo) substrate by double glow plasma. Thermal stability of the coating was investigated at 1400°C for 90 min, while Ar gas was inputted to hold the vacuum pressure. The microstructure of the surface and interface of the Ir coating were observed by SEM and TEM. The phase transition of the coating was determined by X-ray diffraction. Many micropores and microbubbles appeared in the surface of the as-heat treated coating. The interfacial reaction between the Mo substrate and Ir coating occurred during heat treatment, and Ir21.5Mo8.5 phase was formed at 1400°C. The experimental results indicated that the integrity of the Ir coating was not degraded after heat treatment.

Strength properties and dimensional stability of particleboards with different proportions of thermally treated recycled pine particles

Holzforschung ◽  
2016 ◽  
Vol 70 (5) ◽  
pp. 467-474 ◽  
Author(s):  
Paulo Ivan Andrade ◽  
Solange de Oliveira Araújo ◽  
Duarte Miranda Neiva ◽  
Benedito Rocha Vital ◽  
Angélica de Cássia Oliveira Carneiro ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Dimensional Stability ◽  
Lignin Content ◽  
Strength Properties ◽  
Raw Material ◽  
Heat Treated ◽  
Wood Particles ◽  
Partial Degradation ◽  
Thermal Stability Of

Abstract Wood-based panels made of waste and recycled raw material are lacking of dimensional stability. The aim of this study is to evaluate the potential beneficial effect of heat treatment (HT) on the properties of particleboards produced from waste of Pinus sp. used for packaging. The wood particles were heat treated at 180°C, 200°C and 220°C after grinding, and panels were produced with incorporation of 25%, 50%, 75% and 100% HT particles. The materials served as reference were particles without HT. Mass loss at 180°C and 200°C was small but increased significantly to 10.6% at 220°C. The HT caused a partial degradation of hemicelluloses, thereby the relative lignin content increased from 29.7% to 37.8% for the HT220°C samples. Thermogravimetry revealed higher thermal stability of the HT particles. The equilibrium moisture content decreased with HT, e.g. panels with HT220°C showed 30% lower compared to the reference. Swelling of the panels was lowered by 30% (panel with 75% HT material) compared to the reference. The results with HT pine were successful in terms of dimensional stability and lower hygroscopicity; however, the panels lost some strength properties.

scholarly journals Termite Resistance, Chemical and Mechanical Characterization of Paulownia tomentosa Wood before and after Heat Treatment

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1114
Author(s):  
Bruno Esteves ◽  
Helena Ferreira ◽  
Hélder Viana ◽  
José Ferreira ◽  
Idalina Domingos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
New Species ◽  
Thermal Degradation ◽  
Dimensional Stability ◽  
Treated Wood ◽  
Extractive Content ◽  
Paulownia Tomentosa ◽  
Termite Resistance ◽  
Heat Treated

The introduction of new species in forest management must be undertaken with a degree of care, to help prevent the spread of invasive species. However, new species with higher profitability are needed to increase forest products value and the resilience of rural populations. Paulownia tomentosa has an extremely fast growth. The objective and novelty of this work was to study the potential use of young Paulownia trees grown in Portugal by using heat treatment to improve its properties, thereby allowing higher value applications of the wood. The average chemical composition of untreated and heat-treated wood was determined. The extractive content was determined by successive Soxhlet extraction with dichloromethane (DCM), ethanol and water as solvents. The composition of lipophilic extracts was performed by injection in GC-MS with mass detection. Insoluble and soluble lignin, holocellulose and α-cellulose were also determined. Physical (density and water absorption and dimensional stability) and mechanical properties (bending strength and bending stiffness) and termite resistance was also determined. Results showed that extractive content increased in all solvents, lignin and α-cellulose also increased and hemicelluloses decreased. Compounds derived from the thermal degradation of lignin were found in heat-treated wood extractions. Dimensional stability improved but there was a decrease in mechanical properties. Resistance against termites was better for untreated wood than for heat-treated wood, possibly due to the thermal degradation of some toxic extractives.

scholarly journals Tailoring the Glass Composition to Increase the Thermal Stability without Impacting the Crystallization Behavior of Oxyfluorophosphate Glass

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 148-159
Author(s):  
Nirajan Ojha ◽  
Iuliia Dmitrieva ◽  
Wilfried Blanc ◽  
Laeticia Petit
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
Glass Network ◽  
Thermally Stable ◽  
Heat Treated ◽  
The Impact ◽  
Thermal Stability Of

Even though the (75 NaPO3-25 CaF2) (in mol%) glass can be heat-treated into transparent glass-ceramic with Er3+ doped CaF2 crystals precipitating in the volume of the glass during heat-treatment, this glass was found to be a poor glass former, limiting its use as upconverter under 975 nm pumping. In this study, the impact of the glass composition on the thermal, optical and structural properties of the glass was investigated in order to understand how the glass composition can be tailored for the development of thermally stable upconverter glass-based material. The addition of MgO, Fe2O3 and Al2O3 in the NaPO3-CaF2 glass system increases the thermal stability of glass due to the depolymerization of the glass network. However, the changes in the glass composition also impacted on the nucleation and growth process. Indeed, CaF2 and other crystals were found in the newly developed glasses after heat-treatment leading to glass-ceramics with lower intensity of upconversion than the (75 NaPO3-25 CaF2) glass-ceramic used as a reference. Glasses were also prepared with different concentrations of Er2O3 and ErF3. These glasses were found to be promising as not only are they thermally stable, but they also exhibit green and red emission with high intensity under 975 nm pumping due to Er3+ clustering.

scholarly journals Effect of Heat Treatment on Water Absorption of Chinese fir Using TD-NMR

2018 ◽  
Vol 9 (1) ◽  
pp. 78 ◽  
Author(s):  
Yulei Gao ◽  
Kang Xu ◽  
Hui Peng ◽  
Jiali Jiang ◽  
Rongjun Zhao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Water Absorption ◽  
Bound Water ◽  
Treated Wood ◽  
Free Water ◽  
Scientific Basis ◽  
Transport Processes ◽  
Chinese Fir ◽  
Frequency Coding ◽  
Heat Treated

Knowledge of the dynamic changes in the water absorption process of heat-treated wood is important for providing a scientific basis for the reasonable application of heat-treated wood, especially for outdoor applications. Nuclear magnetic resonance (NMR) techniques provide detailed information about the moisture components and moisture transport processes in wood, which are not available with other methods. In this work, water absorption of untreated and heat treated Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) heartwood was investigated using various NMR methods. The heat treatment temperatures were varied between 160 °C and 220 °C. According to the spin-spin relaxation time (T2), there were two components of water in the samples heat-treated at 160 °C and 180 °C as well as the untreated sample, while three components of water were found in the samples heat-treated at 200 °C and 220 °C, and the mass of each component was calculated by the integral peak areas of the T2 curve. The amount of bound water and free water in heat-treated samples were less compared to the untreated ones, and the water absorption decreased correspondingly, due to the increasing heat-treated temperature. The results obtained by one dimensional frequency coding indicated that the heat treatment made wood difficult to be accessed by moisture. Besides, NMR images revealed that the free water absorption in latewood was faster than in earlywood, but earlywood could absorb more water than latewood.

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