Hot-pressing Temperature Research Articles

Synthesis and characterization of a bio-aldehyde-based lignin adhesive with desirable water resistance

Wood-based panels find widespread application in the furniture and construction industries. However, over 90 % of adhesives used are synthesized with formaldehyde, leading to formaldehyde emission and associated health risks. In this study, an entirely bio-based adhesive (OSL) was innovatively proposed through the condensation of multi-aldehyde derived from the oxidization of sucrose (OS) with sodium lignosulfonate (L). This approach positioned oxidized sucrose (OS) as a viable substitute for formaldehyde, ensuring safety, simplicity, and enhance water resistance upon reaction with L. The optimization of the OSL adhesive preparation process involved determining the oxidant level for high sucrose conversion to aldehyde (13 % based on sucrose), the mass ratio of OS to L (0.8), and hot-pressing temperature (200 °C). Notably, the shear strength of 3-plywood bonded with the developed adhesive (1.04 MPa) increased to 1.42 MPa after being immersed in hot water at 63 ± 3 °C for 3 h. Additionally, the plywood specimens exhibited excellent performance after soaking in boiling water for 3 h, resulting in a shear strength of 1.03 MPa. Chemical analysis using Fourier-transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) confirmed an addition reaction between L and OS, forming a dense network structure, effectively enhanceing the water resistance of OSL adhesives. Furthermore, compared with lignin-formaldehyde resin adhesive (LF), the OSL adhesive exhibited superior wet shear strength. This study offered an innovative approach for developing lignin-based adhesives utilizing a biomass aldehyde (OS), as a promising substitute for formaldehyde in the wood industry. The findings indicated that this approach may advance lignin-based adhesives, ensuring resistance to strength deterioration under highly humid environmental conditions.

Study on strengthening and toughening mechanism of Ti-Ni-Al ternary metallic-intermetallic laminated composites: Effect of interlaminar phase and Ti2Ni morphology

Further improving the strengthening and toughening properties of traditional binary metallic-intermetallic laminated (MIL) composites has become an urgent problem to be solved. In this work, a thin 0.02 mm Ni layer was added between the Ti and Al layers to prepare novel Ti-Ni-Al ternary MIL (TNA-TMIL) with multi-layer heterostructure (HS) characteristics, which significantly improved strength and toughness. TNA-TMIL composites include intermetallic layers (Ni-Al and Ni-Ti), unreacted metal layers (Ti-6Al-4V and Ni) and special morphology Ti2Ni in the Ti-6Al-4V layers. With the rise of hot-pressing temperature from 710 ℃ to 900 ℃, the eutectoid reaction and the increase of Ni element in Ti-6Al-4V alloy caused the morphology of Ti2Ni in the Ti-6Al-4V layer transition from island-like to network-like/needle-like to transition regions and finally formed needle-like Ti2Ni morphology. The electron backscatter diffraction (EBSD) analysis of the needle-like Ti2Ni shows that it has a weak cubic texture, and its fine grains are composed of dynamic recrystallization (DRX) and deformed grains. Nano-indentation and compression experiments indicated that the mechanical properties of TNA-TMIL composites are related to the different HS combinations and the morphology changes of Ti2Ni in the Ti-6Al-4V layer. This discovery may provide experience for designing and developing ternary MIL composites.

A closer examination of white-rot fungal mycelia assisted wood bonding

This study investigated the adhesion at the interface between fungal mycelia and wood in detail, focusing on the evaluation of different bonding systems and the influence of hot-pressing temperature on bonding strength.

Curing Behavior of Sucrose with p-Toluenesulfonic Acid.

With respect to the fossil resources shortage, the development of bio-based wood adhesives is an important research topic in wood science. There has been research on using sucrose for bio-based adhesives. However, a high acid catalyst content and a high hot-pressing temperature are required when manufacturing particleboards. In this study, to explore the possibility of p-toluenesulfonic acid (PTSA) as a promising acid catalyst for sucrose-based adhesives, the curing behavior of sucrose with PTSA (Suc-PTSA) was clarified. The thermal analysis results showed that the thermal properties of sucrose decreased significantly with the addition of PTSA. Based on the results of the insoluble matter rate, the optimal mixture ratio and heating conditions were determined to be 95:5 and 180 °C for 10 min, respectively. According to the results of FT-IR, the heat-treated Suc-PTSA contained furan compounds. In the context of the dynamic viscoelasticity, the onset temperature at which the storage modulus (E') begins to rise was significantly lower than those of the other sucrose-based adhesives. PTSA has the potential to cure sucrose more efficiently and at lower temperatures than previous sucrose-based adhesives, making it a promising acid catalyst for sucrose.

Mechanical properties and moisture diffusion in hot-pressed jute fiber composite subjected to hygrothermal ageing

Jute fiber is one of the most extensively used eco-friendly natural fibers that are hydrophilic. The performance of natural fiber-reinforced composites is affected by the diffusion of heat and moisture from the environment in addition to the exposure time. In the present investigation, the ultimate tensile strength, displacement at fracture, and energy at yield of the jute fiber-reinforced composite under different hygrothermal (temperature and relative humidity) conditions are investigated. The samples were prepared by hand lay-up technique and the laminates were hot pressed on a hydraulic press apparatus. The specimens were further exposed to a hygrothermal environment using a humidity cabinet (with an inbuilt thermometer and hygrometer) for varied intervals of time of 4, 16, and 64 h. The longitudinal tensile stress ( σ) increased at lower hot-pressing temperatures and minimum hygrothermal ageing and it decreased at a higher temperature. Upon increase in hygrothermal ageing, σ decreased at all temperatures. The energy at yield point ( E) decreased significantly at lower temperatures and minimum hygrothermal ageing while minimum changes were observed at a higher hot-pressing temperature. The diffusion of moisture as a function of time and temperature explained using Fickian law. The initial region showed nearly linear variation. With continuous hygrothermal ageing, the equilibrium, considering partial pressure, was achieved between the environment and moisture inside the sample. The microstructure of the sample processed at lower hot-pressing temperatures followed by hygrothermal ageing of 16 h showed diffusion and fiber pull-out. However, at a higher temperature, matrix cracking was also observed.

Dopant dependent microstructure of hot-pressed SiGe alloys and its implications on thermoelectric properties

SiGe is a proven high temperature thermoelectric material for space application. We have investigated the role of dopants (P and B) on the densification of SiGe alloys. It was observed that on P doping there is a formation of liquidous SiP phase in the SiGe matrix during hot pressing that improves the diffusion across grain boundaries and as a result ∼98 % of theoretical density was achieved. In case of identically prepared B doped samples, the segregation of B resulted in porous microstructure and low density ∼89 %. Such a difference in microstructure resulted a figure-of-merit of ∼1.29 (at 1100K) for n-type SiGe (P doped) and ∼0.86 (at 1100K) for p-type SiGe (B doped) at a hot press temperature of 1273 K. The study suggests that in case of SiGe apart from doping the densification of materials plays a very important role in improving its thermoelectric performance.

Significant impact of melt-blend and hot-press technique operating condition on polyethylene/thermoplastic starch/aloe vera gel film properties

Melt-blend and hot-press techniques were among the most popular methods for producing polyethylene/thermoplastic starch (PE/TPS) polymer blends. However, different operating conditions contributed to the various quality of film made. Thus, this paper focuses on determining the most suitable operating conditions involving melt-blend and hot-press techniques on specific PE/TPS/aloe vera gel (AV) film formulations. Thus, this study determines the best operating condition for producing PE/TPS/AV blend. One-factor-at-a-time (OFAT) method was implemented under six operating conditions: different melt-blending temperatures, pre-heating, hot-pressing pressure, temperature and duration, and cooling application. The result demonstrated that the best melt-blending temperature was 170 °C, having the highest tensile strength (TS) performance. Pre-heating application reduced the thickness, which is suitable for applying single-used plastic and more economical than thicker film. Importantly, this study found the lowest pressure to obtain a smooth surface of film without stickiness during the peeling process from the steel plate after applying the hot-press technique. The same condition faced at 130 °C, hot-pressing temperature produced a smooth and clear film structure. The pro-longed hot-pressing duration reduced the bonding strength of the polymer matrix. Finally, a fast-cooling rate enhances the TS of the film. Therefore, the melt-blending and hot-pressing operating conditions significantly impact the physical and mechanical properties of PE/TPS/AV film. The results of this study are valuable for understanding that each formulation needs a specific processing condition essential as an initial assumption in simulation processes.

Impact of Hot Isostatic Pressing Temperature on Tensile Properties of TA15 Titanium Alloy Produced via Laser Powder Bed Fusion

TA15 titanium alloy holds great significance as a crucial material in the aerospace industry. In order to gain deeper insights into the influence of hot isostatic pressing (HIP) temperature on the tensile characteristics of materials formed through laser powder bed fusion (L-PBF), a comparative heat treatment experiment was crafted, aligning with the HIP treatment temperature settings. Specifically, the temperatures selected for this investigation were 900 °C, 940 °C, 980 °C, and 1020 °C, while the duration of the holding time was set at 2 h. Notably, the microstructure within the β phase region demonstrated distinct disparities between the HIP-treated specimens and those subjected to heat treatment. The heat-treated specimens exhibited the formation of Widmanstatten structure at 980 °C, while the metallographic structure of the HIP-treated specimens consisted of the lath α phase. In heat-treated specimens, an upward trend in temperature from 900 °C to 1020 °C led to a gradual decrease in UTS (995 MPa, 947 MPa, 886 MPa, and 892 MPa), YS (921 MPa, 865 MPa, 799 MPa, and 784 MPa). The elongation (15.7%,14.6%, and 13.3%) diminished as the temperature increased from 900 °C to 980 °C. At 1020 °C, the elongation slightly increased to 13.9%. The HIP-treated specimens showcased a declining trend in UTS (1008.5 MPa, 947 MPa, 886 MPa, and 892 MPa) and YS (939 MPa, 897.5 MPa, 839.5 MPa, and 844.5 MPa) with an increase in HIP treatment temperature from 900 °C to 980 °C, after which they experienced a slight increment upon further elevation to 1020 °C. The elongation (16%,18.3%, and 20.5%) demonstrated a remarkable improvement from 900 °C to 980 °C. At 1020 °C, the elongation decreased to 17.5%.

A fully bio-based soy protein wood adhesive modified by citric acid with high water tolerance

Despite the widespread application prospect of soybean meal flour (SF) as a non-toxic and renewable wood adhesive, the practical application is limited by its poor mechanical properties and water resistance. In this work, a novel SF-based wood adhesive (CSP) was developed using citric acid (CA) as a modifier, which was further designated to produce plywood on a laboratory scale. Moreover, the effects of the mass ratio of CA/SF, hot-pressing temperature, and hot-pressing time on the bonding properties and water resistance of the resulting plywood were investigated in detail. As a result, under the optimal hot-pressing conditions (180 °C, 5 min), high-performance plywood bonded by CSP (CA/SF = 15/100) adhesive was fabricated, whose dry shear strength, cold-water wet shear strength (20 °C for 24 h), and hot-water wet shear strength (63 °C for 3 h) reached 1.65 MPa, 1.99 MPa, and 1.58 MPa, respectively. Due to the easy preparation process, sustainability, and favorable properties, the proposed fully bio-based CSP wood adhesive has great potential for the large-scale fabrication of eco-friendly wood panels in industry.

Performance of particleboard from fast-growing species

Kelempayan (Neolamarckia cadamba) is a fast-growing tree species that can be cultivated in Malaysia. This species has potential as an alternative resource for the Malaysian furniture and panel board industries in the coming years because of a shortage of the current frequently used raw material (rubberwood). A study on potential as particleboard was done. In accordance with Malaysian Standards (MS), this study examined MOE, MOR, IB, and thickness swelling of particleboard with particle sizes of 0.5 and 1.0 mm, densities of 600 and 700 kgm−3, resin contents of 9 and 11 %, and hot press temperatures of 155 and 165 °C. Boards from 0.5 mm particle size, 700 kgm−3 density, and 11 % resin content at 165 °C hot press temperature had the greatest mechanical performance. The boards constructed from particle size 0.5 mm with the density 600 kgm−3 presence 9 % resin and pressed using 155 °C hot press temperature showed the least amount of thickness swelling. The boards complied with the standard requirements. In general, kelempayan wood is a potential raw material for the manufacture of wood composites.

High-performance CH3NH3PbBr3 Polycrystalline Wafer Prepared by Hot-pressing Method

Considering the drawbacks of the common methods for CH3NH3PbBr3 single crystal growth, such as the complicated and uncontrollable process, a simple hot-pressing (HP) method was introduced to fabricate CH3NH3PbBr3 polycrystalline wafers. The effect of hot-pressing temperature on the crystalline quality and corresponding optical and electrical properties of the CH3NH3PbBr3 polycrystalline wafers was investigated. The hot-pressing temperature for CH3NH3PbBr3 was optimized at 150°C, and the optimized CH3NH3PbBr3 wafer exhibited a low defect density (1.55×1010 cm−3), long carrier lifetime (1734 ns), and high carrier mobility (51.24 cm2V−1s−1) as a photoconductive detector. Furthermore, the detector showed a highly sensitive weak light response under 525 nm LED illumination with an optical power density of 84 nWcm−2, exhibiting a high responsivity of 63 AW−1, EQE of 1.5×104 %, and detectivity of 2.33×1013 Jones, and a fast response speed with a rise time of 17.7 μs and a fall time of 57.4 μs has been achieved.

Enset Fiber-Reinforced Polylactic Acid-Based Biocomposites for High-Performance Application

In recent years, there has been growing interest in using plant fibers to reinforce materials in modern manufacturing. This study focuses on the development of a novel biocomposite made from an enset fiber (EF) and polylactic acid (PLA) matrix using compression molding at a hot-pressing temperature of 170 °C and pressure of 7 MPa for 7 min. Before preparing the biocomposites, the fibers were chemically modified with different concentrations of sodium hydroxide (NaOH) and cut into shorter fibers with a 40 mm average length in size. Then, the extent of modifications on the mechanical properties, dynamic mechanical behavior, morphology, and water absorption were investigated. The tensile, flexural, and Charpy impact tests were carried out to evaluate the mechanical properties of the samples as per ASTM standards. Moreover, dynamic mechanical analysis (DMA) and the water absorbency of the biocomposites were investigated, and the results were graphically shown and explained. The results indicate that the biocomposite treated with 5% NaOH exhibited significant improvements in tensile strength, flexural strength, and impact strength compared to the untreated composite. The tensile modulus and flexural modulus of 5% NaOH-modified enset fiber biocomposite were also enhanced by 55.8% and 70.3% compared to untreated enset fiber biocomposite. The highest tensile strength, flexural strength, and impact strength found for the PLA composite reinforced by EF treated with 5% w/v NaOH solution were 20.16 MPa, 30.21 MPa, and 12.02 kJ/m2, respectively. In general, the modification of natural fibers improves adhesion at the interface and therefore decreases the water absorption and improves the dynamic mechanical properties of biocomposites.

Mechanical properties of flexible composites reinforced with high-performance glass fiber multi-axial warp-knitted fabrics

This paper investigates the quasi-static mechanical properties and damage behavior of flexible composites prepared from high-performance glass fiber-based multi-axial warp knitted fabrics as reinforcement and high tenacity environmentally friendly thermoplastic polyurethane as a matrix. The composites were produced by attaching thermoplastic polyurethane (TPU) to the top and bottom of the fabric using a vulcanization machine, followed by hot-pressing for different temperatures and time settings. Moreover, the effects of different preparation processes on the tensile strength, static puncture resistance, and tear strength of flexible composites were investigated in this paper. The results indicated that both hot-pressing temperature and vulcanization time had a significant impact on the mechanical properties of the composites. With an optimum vulcanization temperature of 185°C and a vulcanization time of 10 min, the composite provides optimum tensile strength and puncture resistance. Tear strength is the worst and is related to the reinforcement’s organisational structure and the interfacial bond’s strength. The results of this study are of theoretical and practical significance for applying high-performance multi-axial warp-knitted flexible composites as raw materials in the construction field.

Preparation and characterization of plywood panels using recycled HDPE as a formaldehyde-free adhesive: A comparative study

Formaldehyde-based resins such as urea-formaldehyde (UF) are the most widely used adhesives in the plywood industry. However, due to the concerns about formaldehyde toxicity, there is a need to develop formaldehyde-free adhesive materials. Therefore, the present study aimed to minimize or eliminate the harmful effects of UF resin by using recycled high-density polyethylene (HDPE) from post-consumed fruit packing boxes as a nontoxic adhesive. Three-layer plywood panels using poplar veneers and recycled HDPE films were prepared. UF was used as a control adhesive for the comparison. The influence of three variable parameters in terms of HDPE content (from 80 to 320 g/m2), hot-pressing temperature (from 140 to 180 °C), and pressing duration (from 3 to 8 min) on the properties of plywood panels were evaluated. For evaluation, physical properties, namely water absorption (WA), thickness swelling (TS), and mechanical properties, namely modulus of elasticity (MOE), modulus of rupture (MOR), and glue-line shear strength of the samples, were studied. The findings of this work confirmed that HDPE films gave the values of mechanical properties of plywood panels comparable to those obtained with UF adhesive, even though the adhesive content and pressing time were lower than when the UF adhesive was used. The obtained bonding strength values of HDPE-bonded plywood panels ranged from 0.82 to 1.60 MPa and met the requirement for the European Standard EN 314-2. According to FE-SEM micrographs, the fractured surface of plywood panels with 240 g/m2 of HDPE displayed a homogeneous cross-section area, and a large amount of HDPE was attached to the veneer surfaces. It was found that the average mechanical properties tended to increase with an increase in the pressing temperature and time. The type of adhesive had a significant effect on WA and TS. The smallest values of WA and TS were observed in plywood samples using high contents of HDPE films (240 and 320 g/m2). The optimum conditions were an HDPE loading of 240 g/m2, a hot-pressing temperature of 160 °C, and a hot-pressing time of 5 min. The overall results showed that recycled HDPE had enough potential to reuse as a promising adhesive for the environmentally-friendly plywood manufacturing.

Melamine–Urea–Formaldehyde Resin Adhesive Modified with Recycling Lignin: Preparation, Structures and Properties

The wettability, bonding strength and flexibility of modified melamine–urea–formaldehyde resin adhesive with hydroxymethyl lignin (LMUF) were investigated. Moreover, the curing performance, thermal properties and chemical structure of LMUF were analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electronmicroscopy (SEM), X–ray diffraction (XRD), Fourier–transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C–NMR). The synthesis mechanism of LMUF was also discussed. The results demonstrated that: (1) LMUF resin is characterized by low free formaldehyde and a short pot life. (2) With the increase in hydroxymethyl lignin, the bonding strength and flexibility of the LMUF increased first and then decreased. They reached their maximum when the hydroxymethyl lignin content was 6%–8%, which represented increases of 36% and 102%, respectively. (3) The DSC and TG analyses showed that the LMUF resin had a high hot-pressing temperature, but its thermostability was increased. (4) The XRD and SEM analyses proved that the LMUF resin was characterized by flexibility failure, especially at 6% of hydroxymethyl lignin. (5) Hydroxymethyl lignin is a type of flexible long-chain molecule, which was introduced into spaces between the rigid triazine rings through adhesion and penetration, thus improving the regular single structural form of MUF resin and increasing the compactness of the system. As a result, the resin had stronger deformability and cohesion in the molecules. The bonding strength and flexibility were improved to different degrees.

Bonding wood with uncondensed lignins as adhesives

Plywood is widely used in construction, such as for flooring and interior walls, as well as in the manufacture of household items such as furniture and cabinets. Such items are made of wood veneers that are bonded together with adhesives such as urea–formaldehyde and phenol–formaldehyde resins1,2. Researchers in academia and industry have long aimed to synthesize lignin–phenol–formaldehyde resin adhesives using biomass-derived lignin, a phenolic polymer that can be used to substitute the petroleum-derived phenol3–6. However, lignin–phenol–formaldehyde resin adhesives are less attractive to plywood manufacturers than urea–formaldehyde and phenol–formaldehyde resins owing to their appearance and cost. Here we report a simple and practical strategy for preparing lignin-based wood adhesives from lignocellulosic biomass. Our strategy involves separation of uncondensed or slightly condensed lignins from biomass followed by direct application of a suspension of the lignin and water as an adhesive on wood veneers. Plywood products with superior performances could be prepared with such lignin adhesives at a wide range of hot-pressing temperatures, enabling the use of these adhesives as promising alternatives to traditional wood adhesives in different market segments. Mechanistic studies indicate that the adhesion mechanism of such lignin adhesives may involve softening of lignin by water, filling of vessels with softened lignin and crosslinking of lignins in adhesives with those in the cell wall.

Preparation a novel high performance glucose-based wood adhesive with hyperbranched cross-linked network by air oxidation

Utilizing biomass resources to develop environmentally friendly and sustainable adhesives, replacing traditional petroleum-based adhesives, has become an effective way to solve resource shortages and environmental pollution. Glucose, as the most widely distributed reducing monosaccharide in nature, has great potential to replace aldehyde-based adhesives in the production of artificial boards. In this study, G-PEI adhesive was prepared from glucose and PEI by one pot one-step method on the basis of air oxidation and Maillard reaction. The crosslinking mechanism between glucose and PEI was confirmed through detailed Fourier transform-infrared (FT-IR), 13C nuclear magnetic resonance (13C NMR), X-ray photoelectron spectroscopy (XPS), and liquid chromatography-mass spectrometry (LC-MS) analysis. The results showed that the improvement of G-PEI adhesive bonding properties was attributed to the formation of cross-linking network and the synergistic effect of covalent bond and hydrogen bond. As a biomass adhesive prepared without additional oxidant, the maximum wet strength in boiling water of wood-based panels prepared with G-PEI adhesive reaches 1.55 Mpa under the hot pressure condition of 200 °C. Even if the hot-pressing temperature drops to 160 °C, the wet shear strength in boiling water can still reach 0.67 MPa, which is better than relevant reports. This study revealed a method for the simple preparation of high performance wood adhesives by oxidizing glucose through air.

The characterizations of nanofluid type urea formaldehyde resins

For reducing the emission of formaldehyde, urea formaldehyde (UF) resin adhesives used in the wood-based panel industry are mainly synthesized by adding urea in stages to reduce the molar ratio of formaldehyde and urea. Although the lower molar ratio UF resin has lower formaldehyde emissions, it also has the defects of longer curing time and lower bonding strength when being used in wood-based panel products. In this study, nanofluid type UF resins adhesives were prepared by dispersing SiO2 and TiO2 nanoparticles with six concentrations levels, 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1% into UF resins with 1.0 and 1.3 M ratio by the assistance of ultrasound, respectively. It was found that the excellent thermal conductivity of the nanofluid type adhesives could eliminate the defects of the low molar ratio UF resins. When nano-SiO2 and nano-TiO2 were incorporated, the viscosity increased as the nanoparticles concentration increased, the maximum viscosity increased by 11.7% (1.0UF) and 15.0% (1.3UF) with nano-SiO2, the free formaldehyde content, curing time, and pot life of UF resins declined in varying degrees with nanoparticles loading level increased, the maximum amount of free formaldehyde content reduced by 41.2% (1.0UF) and 43.9% (1.3UF) with nano-TiO2, the maximum reduction of curing time was 25.80% (1.0UF) and 42.6% (1.3UF) with nano-TiO2, the pot life maximum decreased by 39.7% (1.0UF) and 43.0% (1.3UF) with nano-SiO2. Nanofluid type UF resins had much higher bonding strength with lower formaldehyde emission than pristine UF resins after being treated with same hot-pressing in plywood manufacture. The maximum of bonding strength increased by 28.1% (1.0UF) and 28.8% (1.3UF) with nano-SiO2, and the maximum amount of formaldehyde emissions reduced by 48.7% (1.0UF) with nano-SiO2 and 41.9% (1.3UF) with nano-TiO2. Meanwhile, the results showed that nanofluid type UF resin used in plywood manufacture exhibited the ability to decrease the hot-pressing temperature or shorten the hot-pressing time.

Utilization of lychee pruning timber as alternative raw materials for manufacturing tubular particleboard

Lychee pruning timber can annually provide approximately 7.8-million-ton lignocellulose resources for particleboard manufacturing in China instead of discharging or burning, which cause various forms of environmental pollution. Herein, tubular particleboards are manufactured using lychee wood particles and epoxy resin tubes. Chemical composition analysis shows that lychee wood is abundant in cellulose and lignin, and TG and FTIR characterize the degradation of lignin at high temperatures, facilitating close bonding between shavings and enhancing the mechanical properties of tubular particleboards. In addition, principal component analysis (PCA) was applied to comprehensively evaluate the mechanical strength and dimensional stability of particleboard with different hot-pressing temperatures, hot-pressing pressures, and board thicknesses. The 20 mm tubular particleboard manufactured at 210 °C and 3.5 MPa exhibited a modulus of rupture (MOR) of 16.71 MPa, modulus of elasticity (MOE) of 1810.25 MPa, and internal bonding strength (IB) of 0.5 MPa, qualifying the EN standard for P2-type particleboard, which can be used in construction and furniture manufacturing.

Evolution Behavior of Rapidly Solidified Microstructure of a Ti-48Al-3Nb-1.5Ta Alloy Powder during Hot Isostatic Pressing

In this study, Ti-48Al-3Nb-1.5Ta powders were manufactured from cast bars by the supreme-speed plasma rotating electrode process (SS-PREP) and used to prepare hot isostatically pressed (HIPed) material at 1050–1260 °C with 150 MPa for 4 h. The phase, microstructure and mechanical performance were analyzed by XRD, SEM, electrical universal material testing machine and other methods. The results revealed that the phase constitution changed from γ phase to α2 phase and then to γ phase with the material changing from as-cast to powders and then to as-HIPed. Compared with the as-cast material, the grain size and element segregation were significantly reduced for both powders and as-HIPed. When the hot isostatic pressing (HIP) temperature was low, the genetic characteristics of the powder microstructure were evident. With the HIP temperature increasing, the homogeneity of the composition and microstructure increased, and the prior particle boundaries (PPBs) gradually disappeared. The elastic moduli of powder and as-HIPed were superior to those of as-cast, which increased with the HIP temperature increasing. The hardness of as-HIPed was lower than that of the powder. The compressive strength, compressive strain, bending strength, and tensile strength of as-HIPed were higher than those of as-cast. With an increase in the HIP temperature, the compressive strength decreased gradually, and the compressive strain first decreased and then increased.