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Magnesium alloy/PC/ABS composites were prepared by hot-press molding technology. The bonding strength is the crucial factor to influence the comprehensive performance of this composite, and it was closely related to the different processing parameters such as temperature, pressure and time. After exploring their relationship, the optimal hot-press processing condition was obtained. The micro- and nano-structure of composites also received attention. Before hot-pressed, the magnesium alloy surface was treated by micro-arc oxidation in order to construct the nano-sized pores. With the aid of scanning electron microscope (SEM) and atomic force microscope (AFM), a refined mechanical interlocking structure was observed with the formation of coordinate bonds at the interface of an alloy-polymer hybrid. The binding energy of the chemical elements at the bonding interface of the composite was also tested by X-ray photoelectron spectroscopy (XPS) and the analysis concluded that coordination bonds were formed at the bonding interface. The maximum tensile shear strength of the composite reached 9.48 MPa. [ABSTRACT FROM AUTHOR]

Polymer-metal hybrids were prepared by using the ultrasonic-assisted hot-press molding process. The surface of the aluminum alloy is anodized to produce nano-pores with a pore size distribution of 60 to 210 nm. The surface of the anodized aluminum alloy is soaked with a silane coupling agent solution to alter its surface polarity. In addition, PP-g-MAH was used to alter the polarity of polypropylene. The structure and properties of the composites were investigated by tensile shear tests, the microstructure of the bonding interface, and elemental analysis. The results show that adding silane coupling agents can create a chemical connection based on the mechanical interlocking structure of the composite bonding interface, leading to an increase in tensile shear strength. When the aluminum alloy surface was treated with a silane coupling agent with a volume fraction of 4%, the tensile shear strength reached 21.02 MPa, increasing by 20.32% compared to the specimen without the silane coupling agent treatment. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the laser-ablated pattern designs on the bonding performance of single-lap dissimilar joints between Polyamide 6 (PA6) composite reinforced with 15% short glass fibers (PA6-15GF) and 7075 aluminium (Al) alloy in O-temper condition, manufactured through hot-pressing technique, is studied by tensile-shear testing. From the optical microscopy (OM) and scanning electron microscopy (SEM) observations, it is found that laser ablation can create a favorable surface morphology for the adhesiveless joints. This is proved by obtaining a significant improvement in the lap-shear strength of the treated samples which can be up to 36%. According to the X-ray photoelectron spectroscopy (XPS) results, the surface chemistry is altered by generating an active oxide layer which is a more suitable condition for the PA6-Al direct bonding. Moreover, achieving favourable surface characteristics is shown by the static contact angle (SCA) findings with the acquired increase in surface wettability after the laser ablation. It is observed that the SCA can be decreased from 83 ± 2 (for as-received Al) by approximately more than 65%. The results gained from the experiments demonstrate that the shape of the laser-induced surface pretreatment markedly affects the strength of metal/composite single-lap joints (SLJs). [ABSTRACT FROM AUTHOR]

In the study, the bonding strength of phenol-formaldehyde (PF) adhesive on plywood under different hot press temperature and time was evaluated. A mechanical mathematical model was established to analyze the curing process of PF adhesive, in which the parameters of model could be used to predict the bonding strength and change rate of plywood. The thermal curing degree of the adhesive was determined by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) as well as Nuclear magnetic resonance (NMR) were used to analyze the chemical structure of adhesives with different curing degree. The results show that higher of hot press temperature, the shorter of time to reach the target temperature. The changed rate constant of bonding strength and the maximum bonding strength of plywood could be calculated by the mechanical mathematical model accurately, and the temperature at 130°C was the optimal temperature for plywood manufacture in the study. FTIR analysis indicated that the primary reaction of PF adhesive in the alkaline medium was the condensation occurring between hydroxymethyl groups and residual active position of other phenolic rings. NMR data presented that the ratio of -CH2- (34.5–35.1 ppm)/CH2-OH (62.4–63.1 ppm) could be used to evaluate the curing degree of PF adhesive. [ABSTRACT FROM AUTHOR]

The metal and carbon fiber reinforced plastic (CFRP) hybrid parts are increasingly used in automobile industry to meet the demand for vehicle weight reduction. The interface bond strength between metal and CFRP is the key to the part properties. The effects of different surface treatments on the interface bond strength of DP780 Steel/CFRP composite laminate based on hot-press curing integration were studied. Single lap test and single-leg bending (SLB) test were used to characterize the interface bond strength of the hybrid composite laminate. Interface failure mechanism was analyzed through surface roughness, fracture mode and fracture morphology. The experimental results showed that the steel surface treated by laser exhibited the highest surface roughness and the greatest surface energy in contrast to other surface treatments, such as degreasing, acid corrosion and grinding. The single lap test results showed that the laser-treated specimen had the maximum interface bond strength and there were a lot of fibers residues on the steel fracture surface. In SLB tests, there was no gap between the laser-treated steel and CFRP interface. The interface was bonded finely, which greatly improved the interface bond strength. [ABSTRACT FROM AUTHOR]

An isotactic polypropylene/aluminum alloy hybrid was fabricated by a self-made ultrasonic-assisted hot press molding (UAHPM) technology, and the properties and structure at the plastic-metal interface were explored. The surface of aluminum alloy was chemically etched and anodized to form micro- and nano- pore structures. The field emission scanning electron microscopy (FE-SEM) was used to observe the strong micro-nano two-scale mechanical interlocking structures formed at the interface of PP/aluminum hybrid. The element diffusion at the plastic-metal interface was detected by the energy dispersive spectrum. The results showed the stronger isotactic polypropylene/aluminum hybrids were manufactured by the UAHPM technology compared with the traditional press-molded samples. The maximal tensile shear strength of the UAHPMed hybrid reached up to 18.96 MPa, compared with 9.77 MPa for the conventional hybrid. The bonding layer between isotactic polypropylene and the aluminum alloy was 3.7um prepared by the UAHPM technique against 6.2 um for the conventional press molding technology. The thermal property of polypropylene was examined by differential scanning calorimetry (DSC), and crystal structure was characterized by X-ray diffraction (XRD), and the β-crystal of PP existence at the PMH's interface contributes to the excellent plasticity and strong bonding strength. [ABSTRACT FROM AUTHOR]

Hot-press compression molding was used to resinify a renewable source-derived linear 1,4-linked β-D-glucan copolymer, i.e., konjac glucomannan (KGM), via the generation of reactive aldehyde groups that tend to crosslink with hydroxyl groups of the glucans. The optimal molding temperature was found to be around 170 °C, with keeping the pressure at 20 MPa for 3.5 min and controlling the water content of the starting KGM powder to be around 22%. The molded KGM resin sheets were found to be crystallized in the annealed KGM polymorph form. Dynamic mechanical analysis revealed that the softening initiation temperature of the KGM resin was ca. 100 °C due to an onset of an increase in the loss modulus, E". The representative KGM resin sheets obtained under the optimal molding conditions were transparent, colored brown, and exhibited a tensile strength of 20.8 ± 4.5 MPa, Young's modulus of 2.2 ± 0.3 GPa and elongation at break of 1.1 ± 0.2%. [ABSTRACT FROM AUTHOR]

Hot-press compression molding was attempted to resinify two renewable source-derived linear (1→3)-β-D-glucan polymers, i.e., paramylon or curdlan via the generation of reactive aldehyde groups that tend to crosslink with hydroxyl groups of the glucans. As for the paramylon, the optimal molding temperature was found to be around 220 °C, keeping the pressure at 20 MPa for 3 min, due to its highly crystalline structure. On the other hand, the curdlan resin was producible in the temperature range of 180–240 °C at the same pressure and pressing time. Dynamic mechanical analysis revealed a large temperature dependence of the loss modulus, E", for the paramylon-based polymer resin whereas the semi-crystalline curdlan resin was stable in terms of both the storage and loss moduli, E' and E", up to 160 °C. The vaporization of the water formed during the molding, due to the thermal decomposition, and the adsorption of moisture due to the hydrophilic property of the paramylon affected the thermal stability. The curdlan resin exhibited flexural strength and modulus extremely superior to those of regenerated and esterified curdlan films, and even a little superior to those of polyamide-12. The strain at break was comparable to the yield strain of an epoxy resin. On the other hand, the paramylon-based polymer resin was producible, but the resinification property and thermal stability of the paramylon resin was inferior to the curdlan resin due to the former's highly crystalline structure. [ABSTRACT FROM AUTHOR]

The aim of this research was to evaluate the effect of the popped amaranth flour on the rheology, chemical composition, protein digestibility and physical properties of hot-press tortillas elaborated with a wheat, oat and quinoa flour, compared with refined wheat flour. Mixolab C1 (dough stability) increased 33% with amaranth addition. Results showed that tortillas containing 5:5:20 oat:quinoa:amaranth increased 31.4% and 27.1% soluble dietary fiber and protein than control, respectively. Protein "in vitro" digestibility increased 1.02% and crude fat reduced 35.6%. Tortilla treatment 5:5:20 required same force to deform and to rupture at day 6, and showed a lower L* (16.1%) and higher a*(27.4) and b* (23.1%) than control. Texture acceptance was the same, and odor acceptance was lower for tortilla treatment 5:5:20, compared to control. The partial replacement of wheat flour with amaranth:quinoa:oat flour positively influences the protein content, total dietary fiber content and protein digestibility of tortillas. [ABSTRACT FROM AUTHOR]

The microstructures and properties of powder metallurgy Ti-45Al-10Nb (at.%) alloys fabricated by vacuum hot pressing consolidation of milled powder have been investigated. Under the sintering conditions, the alloy exhibits much fine-grained microstructure, which consists of a double phase γ + α2 microstructure containing Ti2AlC precipitates. Tensile properties are measured at 900 °C–1000 °C under a strain rate of 1 × 10−4 s−1. This alloy displayed outstanding high-temperature tensile strength, with tensile strength (UTS) 410.2 MPa and elongation (ε) 12.5% at 900 °C, and UTS 189 MPa and ε 16.7% at 1000 °C, respectively. [ABSTRACT FROM AUTHOR]

The sintering behaviour of 17Ni/(10NiO-NiFe2O4) cermet not only is influenced by the characteristics and impurities of the raw materials but also is dependent on extra pressure during the fabrication process. Our work was concerned with the effect of sintering pressure on the relative density, mechanical properties and electrical conductivity of 17Ni/(10NiO-NiFe2O4) cermet. The nickel-ferrite based cermet was prepared by hot press sintering technology at 1100°C for 120 min, and sintered at pressures ranging from 12 to 24 MPa. The microstructure, phase compositions and mechanical properties were studied by scanning electron microscopy, X-ray diffraction and three-point bending strength tests respectively. It was found that the relative density and bending strength of NiFe2O4 based cermet have a great influence upon the sintering pressure, and that the highest bending strength of 125·89 MPa could be obtained under a sintering pressure of 16 MPa. Meanwhile, it was shown that thermal shock resistance decreased as the sintering pressure increased. [ABSTRACT FROM AUTHOR]

The drying kinetics of poplar lumber was experimentally investigated as a function of drying temperature (115, 135, 160, 185 and 205°C) during a periodic hot-press-drying process. Poplar lumber was dried under contact (compression ratio of 10%) and high-press states (compression ratio of 44%). Compared with the contact-state, the high-press-state showed higher drying rate and higher efficiency of removing free water than bound water in wood. Eight mathematical models from the literature were established to analyze the drying behavior. The Weibull model, with an average determination coefficient R2 of 0.9958, fitted well for all applied drying conditions. The scale parameter decreased with increasing drying temperature and was lower for high-press-state drying compared with that for contact-state drying. Moisture diffusivity and activation energy were calculated according to the Weibull model. Diffusivity increased with increasing drying temperature, with the average value of 1.734 × 10-6 and 3.313 × 10-6 m2/s and activation energy of 34.79 and 32.85 kJ/mol for contact-state drying and high-press-state drying, respectively. Hot-press drying created an M-shaped curve of density distribution, with high density at the two surface regions gradually decreasing toward the core region. The contact state-dried wood showed increased density near the wood surface. Both average density and peak density improved in the case of high-press-state-dried wood. Furthermore, the hydrophilic index of wood for high-press-state drying was lower than that of the contact-state drying, and the opposite was true regarding crystallinity index. The hygroscopicity of high-press-dried poplar decreased with lower equilibrium moisture content and higher moisture excluding efficiency, compared with contact-state-dried poplar. The rapid, high-quality drying of poplar lumber through periodic hot-press was more potentially achieved by the high-press-state compared with contact-state drying. [ABSTRACT FROM AUTHOR]

La modified Pb(Mg1/3Nb2/3)O3-PbTiO3(PLMNT) transparent electro-optic (EO) ceramics with pure perovskite phase were fabricated by the uniaxial hot-press sintering method. An improved hot-press sintering technique with varied atmosphere was proposed to eliminate the pore defects. It consists of four stages: 1) sintering at a relatively low temperature (800°C) in the vacuum atmosphere first, and then in the pure O2atmosphere; 2) sintering in a pure O2atmosphere at high temperature by uniaxial hot-press method; 3) replacing the O2atmosphere with CO2gas to eliminate the residual closed pores; 4) finally exchanging CO2atmosphere with pure O2gas to eliminate the oxygen vacancies. The research results certified that the thermal treatment in the vacuum atmosphere and CO2atmosphere could eliminate the residual closed pores and improve the transmittance of the PLMNT transparent ceramics effectively. By the improved hot-press sintering technique, the optical transmittance of the polished PLMNT transparent ceramics with a thickness of 0.35mm increases from 61% to 64% at 632.8nm. The reasonable explanation was given about the mechanism of the improvements of this sintering technique. [ABSTRACT FROM AUTHOR]

Thermoplastic foams allow manufacturing of lightweight parts with good thermal and acoustic insulation properties. To increase the mechanical properties without changing the part weight, these foams can be transformed into structural foams by a newly developed two-step isochoric and isothermal hot press process. Structural foams consist of a low-density foam core and two high-density polymer skins. The production of a polymer skin on the surface of a foam was realized in a hot press process by heating one tool half to process temperatures above glass transition temperature of the amorphous polymer. To manufacture polymer skins on both sides of the foam, it is necessary to turn the foam upside down and repeat the procedure. Structural foams were manufactured with two different polymer foams with different cell structures and densities. Optical analysis of microsections was used to investigate the formation of the polymer skins and the change in foam structure. This study investigates the applicability of an empirical relationship between part densities and bending properties. It was found, that knowledge about the part density alone is not sufficient for the prediction of the bending properties, because the foam structure (e.g. open or closed foam cells) has a considerable impact on the foam properties. [ABSTRACT FROM AUTHOR]

A new 3D printer equipped novel nozzle structure for continuous carbon fiber-reinforced thermoplastics (C-CFRTP) was developed and the suitable printing conditions were studied. C-CFRTP filament and additional matrix resin were supplied independently using each extruder, which is useful for variety printing and precise form control in 3D printing. To measure the mechanical properties, specimens for tensile strength testing were fabricated using C-CFRTP filament (Vf:50%) without additional matrix resin. The experimental results indicate that the tensile strength and Young’s modulus were approximately 700 MPa and 53 GPa, respectively. The recrystallization effect through annealing after 3D printing yielded no drastic improvement. The mechanical properties were considerably improved by a hot-press treatment after 3D printing. The tensile strength and Young’s modulus increased to approximately 1400 MPa and approximately 90 GPa, respectively. These results suggest that one of the useful applications of C-CFRTP 3D printing technology is preforming of small parts in industrial products. [ABSTRACT FROM AUTHOR]

The 1 to 20 veneers ofEucalyptus salignawere dried using a hot press with a pressure of 0.1–0.4 MPa and a temperature of 120–160°C.The energy consumption and properties of the veneers were examined. Although the contact angle (CA) was increased, the value of modulus of elasticity (MOE) was increased and energy consumption (Q) was reduced as the pressure increased. Three regression equations (pressure, temperature, veneer numbers as functions of Q, CA, MOE) were developed and a nonlinear programming model was derived with operation research theory to obtain the minimum Q or most desirable properties process under some production constraints. In cases where minimum Q is desired, the maximum CA of 180° and MOE of 18 GPa are required. The optimal solution was the minimum Q of 176.48 KJ, which can be obtained with a pressure of 0.4 MPa, temperature of 160°C, and veneer number of 5, which makes CA and MOE for the hot-press-dried veneer equal to 133.30° and 4.53 GPa, respectively. [ABSTRACT FROM PUBLISHER]

Poly (styrene-4-vinylbenzyl chloride) (PSVBC) was synthesized by polymerization of 4-vinylbenzyl chloride and styrene. FTIR was used for characterization of PSVBC and for curing of three protein/PSVBC adhesives (proteins include potato, corn, and pea proteins). Protein-PSVBC adhesives were investigated for bonding maple veneers. The shear strength and water resistance of the resultant maple laminates were evaluated. More specifically, the effects of the NaOH concentration, hot press conditions (temperature and time), total solids content, and protein-PSVBC weight ratios on the shear strengths and water resistance were studied. The addition of PSVBC improved the wet shear strength of the laminates from 0.1 to 0.85 MPa for potato-PSVBC adhesive and from 0.1 to 0.73 MPa for corn-PSVBC adhesive. However, the addition of PSVBC did not increase the wet strength of the laminates for the pea-PSVBC adhesive. [ABSTRACT FROM AUTHOR]

The demand for carbon fiber-reinforcement plastic is expanding rapidly in the vehicle industry because of its specific strength and stiffness. More lightweight vehicle bodies need to be mass produced, resulting in a need for the development of lower cost materials and lower cost fabricating methods. Hot-press molding requires less time than conventional processes, such as autoclave processes. In this study, the hybrid material chosen was carbon fiber-reinforced plastic-X5CrNi18-9 stainless steel. The hybrid material fabricated by hot-press molding was examined to determine the optimal fabrication. The fabrication conditions were considered with respect to the temperature, time, pressure, etc. A tensile test and 3-point bending test were conducted to examine the mechanical properties of the hybrid material. In addition, bonding interfaces were observed by optical microscopy. The results suggest that the epoxy resin tends to be lost to the outside if the pressure is too high (>1.2 MPa). Therefore, it is important to identify the appropriate pressure level. The hybrid material rupture faces were examined through a bending experiment. As a result, the hybrid material, which was fabricated by hot-press molding, exhibited good cohesion between the carbon fiber-reinforced plastic and X5CrNi18-9 stainless steel surfaces. [ABSTRACT FROM PUBLISHER]

This study aims to optimize and characterize hot pressed polyamide/steel hybrid joints as a potential solution for reducing energy costs in public transport through structural lightweighting. The mechanical performance of these joints is compared to traditional bonding methods, specifically investigating two types of joints: PA66/steel and PA12/steel. A design of experiments approach is employed to explore the influence of process parameters, with a particular focus on the cooling rate and heating temperature as key factors. By determining the optimal process parameters, the study emphasizes the importance of reaching the polymer pyrolysis point and achieving the fastest cooling rate to achieve optimal results. The findings reveal that these hybrid joints exhibit comparable average shear strength values to bonded joints, showcasing their potential as effective joining methods. In conclusion, future developments in hybrid polymer/metal joining processes utilizing thermal methods should prioritize rapid and uniform heating at the polymer/metal interface to initiate pyrolysis selectively at the polymer surface for bond formation. Subsequent rapid cooling is essential to cease pyrolysis and prevent polymer degradation within its volume. These insights are crucial for successful implementation of such processes in various industrial applications. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research is conducted to improve the performance of plant fiber-based composites by inserting microcrystalline cellulose (MCC). MCC was incorporated into a mixture of recycled high-density polyethylene (rHDPE) and cantala fiber at a ratio of 1, 2, 3, and 4% wt. The composites rHDPE/cantala fiber/MCC were fabricated via a twin screw extruder followed by a hot press. The composite's mechanical, physical, and thermal properties were tested to investigate the effect of adding MCC. It was observed that the enhancement of MCC led to a significant improvement in the mechanical performance of the composite. Adding 4%wt MCC resulted in a significant improvement in mechanical properties of 50.7%, 31%, and 37.7%, respectively, in tensile strength, bending strength, and impact strength compared to rHDPE/cantala composite without MCC. Adding MCC up to 4% wt slightly increased the composite density from 0.88gr/cm3 to 0.90 gr/cm3. The enhancement of MCC did not significantly change the diffraction peak position of the composite. However, composite crystallinity increased by 6.7%. In addition, the augment of MCC increased the thermal stability of the composite, as indicated by the delay in composite degradation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the mechanical properties of single and double-layer woven sisal mat-reinforced PP composite panels. Sisal fibers were extracted using the manual decortication method, resulting in fibers with a density of 1.43 g/cm3 and a diameter ranging from 0.4 mm to 0.6 mm. To improve the bonding between the sisal fibers and the matrix, the fibers were hand-spun into yarn and woven into mats. The study focuses on the unique material combination and the use of sisal as a natural fiber reinforcement. The 18 mm thick panels were tested for water absorption following ASTM D570, compression strength, and tensile strength following ASTM D3039 using the UTES-100 High Precision universal strength tester machine. Composite panels with single layers of 10% and 15% woven fabric mat, loaded with 8 kg and 10 kg, exhibited compressive strengths of 11.6KN and 12.5KN, respectively. Panels reinforced with two layers of 20% and 30% sisal woven fabric mat, loaded with 8 kg and 10 kg, had compression strengths of 12.2KN and 12.5KN, respectively. Moreover, composite samples with 15% single layer and 30% double-layer sisal woven fabric mat demonstrated a equal compression strength of 12.5KN, falling within the range recommended by ISO13006:2012. The tensile strength of 16.99MPa, although slightly below the recommended ISO13006 value of 20MPa for commercial-grade panels, indicates promising results. The study's findings suggest that higher fiber content and additional reinforcement layers lead to increased compression and tensile strength. Furthermore, the moisture absorption rate of the developed composite panels was significantly lower than the 0.5% water absorption rate authorized by the American National Standard Institute. [ABSTRACT FROM AUTHOR]

In the present study, lightweight high-strength carbon nanotubes (CNTs) reinforced aluminium-based composite was fabricated through powder metallurgical processing. The effect of planetary milling and cryogenic assisted milling on the structure, morphology, mechanical properties, phase composition, and thermal stability of CNTs reinforced Al6082 Al nanocomposites powders was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM)- Energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), and indentation techniques. The CNTs in the Aluminium (AL) matrix were distributed uniformly after 50 h of milling. Further, the cryomilling of 50 h milled Aluminium matrix composites (AMC) decreases agglomeration even more and was successful in cleaving the nanotubes as well as minimising entanglements. The broadening of diffraction peaks suggests a reduction in the crystallite size (from ~36 to ~20 nm) and an increase in induced strain. Milled powders were consolidated through the hot-press and spark plasma sintering technique. The mechanical properties of these AMCs were evaluated through indentation for hardness (>250 HV) and compressive testing techniques. SPSed samples reported better properties in comparison to hot-pressed samples. It is discovered that post-CM of Mechanical Milling (MM) powder aids in overcoming issues related to the agglomeration of Al/CNT composites, and the goal to fabricate tangle-free CNT reinforced composite was achieved. Moreover, it showed enhanced mechanical properties with a maximum yield strength of 210 MPa and good synergy between strength and ductility. [ABSTRACT FROM AUTHOR]

In the present work, acrylonitrile-butadiene-styrene (ABS)/glass fiber (varying fiber orientation angle) and with different % of carbon black (CB) particles-based hybrid composites are fabricated by hot press compression molding technique. Prepared composites were examined under marine conditions in sea water medium and erosion behavior under erodent particles entrained in gas fluid and found reduced impact. Morphological studies are studied through scanning electron microscope. Material removal mechanism is found to be micro-cracking at the impingement angle of 90°. Additionally, numerical analysis for the composite material with respect to single particle impact for erosion was conducted using LS-DYNA. [ABSTRACT FROM AUTHOR]

This article investigates the free vibration and damping characteristics of carbon fiber-reinforced sandwich cylindrical shells with 3D reentrant auxetic cores (3D RSCSs). Finite element analysis based on the modal strain energy method is utilized for simulated predictions, while a theoretical model based on the Rayleigh-Ritz method and third-order shear deformation theory (TOSDT) is used for theoretical predictions. Through a combination of hot press molding and interlocking assembly, all-composite 3D RSCSs specimens are manufactured. The modal characteristics of 3D RSCSs are obtained by hammer excitation modal tests. The prediction for modal properties shows good agreement with the experimental tests. Furthermore, the influences of fiber ply angles and geometric parameters on the natural frequency and damping loss factor are thoroughly investigated, which could be helpful to guide vibration analysis of lightweight metamaterials cylindrical shells with negative Poisson's ratio and promote its engineering application in vibration reduction. [ABSTRACT FROM AUTHOR]

In our research described herein, the hot pressing treatment at 90 °C under 2 tons of pressure on solution cast polymer nanocomposite (PNC) films based on a host matrix of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) and poly(ethylene oxide) (PEO) with varying polymer blend compositions (20, 50, and 80 wt% P(VDF-HFP) or PEO) and 2 wt% zinc oxide (ZnO) nanofiller, was performed; the effects of this treatment and the composition variations on the optical, thermal, and dielectric properties was explored. The ultraviolet-visible wavelength range study revealed slightly reduced absorbance and a little increased energy band gap after the hot pressing of the nanocomposite films. Differential scanning calorimetry of the solution cast-hot pressed (SC-HP) PNC films explained the reduced thermal stability of the poly(ethylene oxide) crystallites and also the degree of crystallinity. The broadband dielectric measurements of these materials, at 27 °C, confirmed significant changes in various dielectric polarization processes, demonstrating a large redistribution of constituent interfaces by the hot press treatment. Additionally, the 90 °C hot pressed PNC film of equal polymer compositional ratio was further hot pressed at 130 °C and 160 °C, step by step, and characterized to examine the variations in dielectric properties. The properties of these thermally treated composite films are discussed concerning their use for flexible device applications. [ABSTRACT FROM AUTHOR]

Employing plant and animal-based biodegradable resources as reinforcement in polymeric composites has undeniable advantages on synthetic fibres, including low cost, renewability, biodegradability, low energy consumption, and easy and safe handling. Bagasse is agricultural waste, while chicken feathers can also be collected from poultry industry waste – both hold the potential to be used as fibre reinforcement in polymer matrix composite. The incorporation of both hybrid fibres together might have a synergistic effect on several properties. In the present research, composites at 5% fibre weight were prepared using a hot-press machine, altering the contribution of individual fibre, keeping bagasse and chicken feather at the ratio of 1:1, 3:1 and 1:3. Subsequently, tensile, flexural, impact, hardness and water absorption tests and thermo-gravimetric analysis were executed. Composite materials with a greater portion of chicken feathers (bagasse:chicken = 1:3) demonstrated superior mechanical properties, as well as better water absorption, thermal stability as compared to composite materials with a more significant proportion of bagasse fibre. To ensure excellent adhesion between polymer matrix and fibre, a significant factor for excellent reinforcement, chemical treatment with 5% NaOH was conducted on both fibres. Five per cent NaOH-treated hybrid fibre-reinforced composite outperformed untreated composite in impact strength, hardness, and water absorption. [ABSTRACT FROM AUTHOR]

This study investigated the influence of moisture absorption on the electromagnetic (EM) wave absorption performance and mechanical strength of a radar-absorbing structure (RAS) with nickel-coated pristine glass fibers and polyamide 6. To construct the RAS, nickel was deposited on pristine glass fibers via electroless plating, and the RAS was fabricated using a hot-press process. An environmental test was conducted under a high humidity of 85%, and the EM wave absorption capacity of the RAS was measured at 2-week intervals. Moreover, compressive and interlaminar shear tests were conducted to verify the degradation of mechanical strength and the effect of the nickel coating on moisture absorption resistance. The test results revealed that immersion in moisture degraded the EM absorption capacity of the RAS. Nevertheless, an improvement in the mechanical strength of the RAS after saturation was observed due to the nickel coating. [ABSTRACT FROM AUTHOR]

In this study, poly(glycidyl methacrylate-co-styrene) (PGS) was investigated as a curing agent for soybean flour (SF)-based wood adhesives in the presence of polyethyleneimine (PEI). The seven-ply plywood panels made with the SF-PGS-PEI adhesives passed a three-cycle soak test that is the industrial standard test for evaluation of the water resistance of decorative plywood panels in the USA. SF, PGS, and PEI were found to be all essential components for the adhesives. The mixing of SF and PGS first, followed by addition of PEI, was found to be the only mixing order that was able to result in superior properties of the adhesives. The viscosity of SF-PGS-PEI adhesives remained relatively low for at least 60 min of the storage, which made the adhesives easy to use. Effects of weight ratios among SF, PGS, and PEI in the adhesives, the molar ratio between glycidyl methacrylate and styrene in the PGS, and hot-press conditions of making the plywood panels on the water resistance of the resulting plywood panels were extensively investigated. The adhesion mechanisms are discussed in detail. [ABSTRACT FROM AUTHOR]

Urea-formaldehyde (UF) resin is one of the most commonly used wood adhesives for making particleboards. However, UF emits carcinogenic formaldehyde and is derived from nonrenewable petrochemicals. In this study, a new formaldehyde-free wood adhesive that is based on soy flour and a renewable material-based curing agent (CA) were prepared and evaluated for the preparation of M-2 grade particleboards. The new CA was derived from ammonia and epichlorohydrin that can be derived from renewable glycerol. The composition of the adhesive was soy flour/sodium hydroxide/CA at a dry weight ratio of 9/0.3/1.0. The modulus of rupture, modulus of elasticity, and internal bond strength met the minimum industrial requirements of M-2 particleboards using the following variables: hot-press temperature of 190 °C, hot-press time of 240 s, the adhesive usage of the face particles of 12 wt.%, the adhesive usage of the core particles of 10 wt.%, and the target particleboard density of 0.80 g/cm3. [ABSTRACT FROM AUTHOR]

A formaldehyde-free adhesive consisting of soy flour, polyethylenimine, maleic anhydride, and sodium hydroxide was investigated for making randomly oriented strandboard (R-OSB) and oriented strandboard (OSB). The hot-press conditions and the adhesive usage rate were optimized in terms of enhancing internal bond strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE) of the resulting R-OSB and OSB. The IB, MOR, and MOE were the highest at a hot-press temperature of 170°C, a hot-press time of 4-5 min, and an adhesive usage rate of 7%. The strengths of the OSB panels made with this formaldehyde-free adhesive were compared with those of commercial OSB panels purchased at a local Home Depot store. [ABSTRACT FROM AUTHOR]

Thallium doped bismuth telluride alloys (Bi2-xTlxTe3) are synthesized using solvothermal method, and pellets are formed using hot-press machine by applying 60 MPa pressure at 553 K temperature for 5 min. The X-ray powder diffraction for the as-synthesized Bi2-xTlxTe3alloys indicates phase purity and crystallographic structures. Scanning electron microscopy indicates highly compact plate-like structures for hot-pressed pellets. The energy dispersive X-ray spectrophotometer predicts a stoichiometric ratio of 2:3 for Bi and Te in the Bi2Te3. The newly prepared Bi2-xTlxTe3pellets could be utilized as an efficient material in thermoelectric devices for power generation from waste heat. [ABSTRACT FROM AUTHOR]

The presented research investigates the influence of braided flax woven-fabric filled with polylactic acid (PLA) polymer on interlaminar shear strength (ILSS), free vibration, heat deflection temperature (HDT) and water absorption. For this purpose, flax fibre-braided yarn and its fabric are prepared using solid braiding and plain weaving techniques. Then, PLA biocomposites are developed by solution casting and hot-press moulding processes. Shear test results showed, the addition of braided flax fibre increased the ILSS of composites compared to unreinforced PLA. Natural frequencies of the composite beams are improved with the braided flax reinforcement. Composites filled with three fabric layers showed higher frequency due to higher structural strength and stiffness associated with these composites. Bio-composites HDT is enhanced with the addition of braided flax fibre from 61.78% to 132.97%. The results of a water absorption test in distilled and seawater revealed that the composites have a relatively high water uptake in distilled water. [ABSTRACT FROM AUTHOR]

Novel Ti/Al laminated composite embedded with particles of the high entropy alloy Al0.5CoCrFeNi were produced by vacuum hot press sintering at 650°C. The microstructure of the laminated composite was investigated using XRD, SEM, EDS, TEM and EBSD techniques. It was found that a thin layer of Al3Ti was formed at the Ti/Al interface. There were no obvious defects between the Al0.5CoCrFeNi particles and Al matrix, achieving a good interfacial bond. The tensile properties of the material were tested at room temperature. The results of the tensile test indicated that the material exhibited an elongation to failure of 59% and an average tensile strength of 240 MPa, demonstrating excellent plastic deformation capability. During the tensile process, the expansion of fractures and cracks in Al0.5CoCrFeNi particles can consume energy, which helps to improve the material's ability to undergo plastic deformation. Based on the morphologies of tensile fracture, it has been observed that the fracture surface of high entropy alloys exhibits a mixed fracture mode consisting of both brittle and plastic fracture. The brittle BCC phase has been identified as the main cause of cracking in HEA. Ultimately, the material fractures due to necking. [ABSTRACT FROM AUTHOR]

It is crucial to develop practical procedures for the control and reduction of pesticide residues in oil productions from farm to dining table. In this study, the dissipation behaviors of typical fungicide from rapeseed to oil production were studied to reveal relationship among spraying stage, application dosage, household oil processing stage, and pesticide residues. In the field trials, rape plants were sprayed with carbendazim at three different dosages during flowering period. Transfer assessment of carbendazim residues from rapeseed to oil production during household oil processing via different press techniques was determined using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS). The recoveries of carbendazim in rapeseed samples, meals after squeezing samples, and rapeseed oil samples ranged from 82.5% to 93.6% with relative standard deviations (RSDs) ＜5.2%. The validation results illustrated that the methods were reliable and sensitive. The average processing factor (PF) during household oil processing via hot press technique and cold press technique was 0.15 and 0.51, respectively. This study demonstrated that household oil processing could significantly reduce the pesticide residues, especially by hot press technique. [ABSTRACT FROM AUTHOR]

The selection of materials with the required properties was developing rapidly. There is no single rule to choose suitable material for a particular product. The complexes interrelation among the properties of composites makes more difficult to suggest suitable material for material scientist. The forecasting of relationship among material properties with throughput screening methods can help for the discovery of novel materials. The conventional way of selection of material need more investigations and time consuming. Recently, machine learning approaches are widely used in mechanical domain. Hence in this work, machine learning-based method was proposed to discover the relationship between the properties of natural fibres composites. To apply machine learning approach, there are 26 different natural fibres composites of Coir, Jute, Banana etc. were taken in to consideration. These materials are reinforced with pure export with different manufacturing methods such as Hand layup, Spray layup, Hot press moulding, and Compression moulding to produce the samples as per ASTM standards. The properties like density, tensile strength, hardness etc. were measured and interrelation among them was recognised using proposed method. [ABSTRACT FROM AUTHOR]

A new formaldehyde-free wood-adhesive system consisting of kraft lignin and polyethylenimine (PEI) was investigated for making two-ply plywood. The lignin-PEI adhesive was prepared by mixing a kraft lignin solution and a PEI solution at room temperature. The mixing time of the lignin and PEI had little effect on the shear strength when it was ≥40 min. The shear strength of the resulting wood composites increased slightly as a function of increased hot-press time from 2 to 9 min. The optimum hot-press temperature was 140°C. The lignin-PEI adhesive with a lignin/PEI weight ratio of 2:1 resulted in the highest shear strength and the highest water resistance. The wood composites bonded with the lignin-PEI adhesives retained very high shear strengths after undergoing a water-soaking-and-drying test, as well as a boiling water test. Storage of the lignin-PEI adhesive for three days did not have detrimental effect on plywood shear strength. The molecular weight (Mw) of PEIs in the range of 70 000 to 150 000 had little effect on the shear strength of the resulting wood composites. The cure chemistry of this lignin-PEI adhesive was proposed to be similar to that of the quinone-tanning process. [ABSTRACT FROM AUTHOR]

Milled waste feathers and chopped kenaf short fibers were used as the matrix resin and reinforcements, respectively, and the production of totally bio-based composites was attempted via hot-press compression molding, changing the fiber content and/or fiber length of the kenaf fibers to optimize the properties. The tensile strength of the composites increased with increasing the fiber content at first. However, the increase of the tensile strength of the composites leveled off and then decreased over the fiber content of 30 wt% due to the occurrence of insufficient filling of the matrix feather resin around the fibers which, we suggest, was due to the low fluidity of the feathers during the molding. However, the thermal stability could be enhanced when the fiber content was set at over 50 wt%. The increase of the loss modulus, E″, of the composites in the temperature range above the softening temperature of the feather resin was greatly suppressed, and E″ became almost unchanged, even at 200 °C, when the fiber content was set at 60 wt%. [ABSTRACT FROM AUTHOR]

Cu-Al2O3 composite materials combining the good electrical of copper matrix and the high hardness of Al2O3 ceramic particles show great performance in electronics, electrical sliding contacts fields. However, the relationship of a dilemma between strength and ductility has become a limitation for the development of copper matrix composites. The previous works indicated that fine grain powders can improve interfacial bonding between the copper matrix and Al2O3 particles to further enhance strength while maintaining ductility. In the present work, the multiscale-alumina particles reinforced copper matrix composites were successfully fabricated by mixing high-energy ball milling and consolidation of hot-press sintering. SEM and TEM were used to observe the powder morphology and microstructure of Cu-Al2O3 composites. The results show that the reinforcing phase Al2O3 particles are uniformly dispersed in the copper matrix, which improves interfacial bonding between the copper matrix and Al2O3 particles. Especially, the micro Al2O3 particles play an important role in achieving an excellent tradeoff of strength and ductility in the Cu-Al2O3 composite. In addition, the microhardness of Cu-Al2O3 composites can be greatly improved by using the high-energy ball milling and hot-press sintering process. The research idea of this paper can provide a reference for other composite materials that need to improve mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, hexagonal barium ferrite thick films with a thickness of about 90 μm were prepared on alumina substrates by screen printing method. Microstructure and magnetic properties of the thick films have been studied. The results show that organic vehicles have a great influence on the microstructure of the ferrite thick films. It is found that the density and surface flatness of the barium ferrite thick films can be improved greatly by hot-press sintering process. The barium ferrite films prepared by hot-press sintering show a clear magnetic anisotropy. Along the easy axis, the squareness ratio of the hexagonal barium ferrite thick films is about 0·75 with a coercive field of 3·4 kOe. A prototype of microwave circulator with the prepared BaM thick films was fabricated. [ABSTRACT FROM AUTHOR]

Densification, i.e. the transverse compression of sawn timber has been studied and commercialised for well over 100 years but remains an expensive niche product with low annual production volumes. One reason for this is the reliance on time-consuming batch processes in a hot press. To solve this, a continuous densification process using a belt press, capable of densifying full-sized sideboards was developed. However, there is insufficient knowledge about the effect of knots on the densification outcome. The objective of this study was to assess how different knot parameters affect the densified wood in terms of damage and deformation to the knot itself and the surrounding wood material. Multivariate data analysis methods were applied to a dataset of 171 knots, described by 23 variables. The data showed that it is possible to densify knots in a continuous process without causing damage. Especially sound knots are often unproblematic, even at relatively large sizes, while densifying dead knots often resulted in unacceptable damage to the knot or the surrounding wood. From a material selection standpoint, any knots bleeding into the board edge and dead knots greater than 20 mm in diameter should be avoided altogether. [ABSTRACT FROM AUTHOR]

In this study, glycidyl methacrylate (GMA) was grafted onto spirulina protein isolate (SPPI), a novel raw material, to increase its water resistance and create an eco-friendly wood adhesive. Papain used as the denaturing agent in the grafting procedure and ammonium persulfate (APS) as the radical polymerization initiator. Based on the water-resistant bonding strength of the grafted polymer, the factors that affect the grafting reaction were analyzed and the reactive conditions were optimized single-factor experiments. According to the most optimum reaction conditions and the optimal preparation conditions, the SPPI-GMA adhesive showed that the wet strength 1.45 MPa was improved around 210% (the dry strength improved around 100%) compared to the untreated SPPI. The results of Fourier transform infrared spectroscopy (FT-IR),13C-Nuclear magnetic resonance (13C-NMR) and X-ray diffraction (XRD) indicated that the GMA had been grafted on the SPPI successfully. In addition, the cure temperature of SPPI-GMA adhesive was analyzed by the Differential scanning calorimetry (DSC). Thus, the SPPI- GMA adhesive has the potential to be applied to the wood industry. [ABSTRACT FROM AUTHOR]

Resinification of milled waterfowl feathers was attempted via a conventional hot-compression molding and its resinification behavior and the physical properties of the resultant resin were investigated. The hot-compression molding using the wet feather powder was found to be effective to achieve full resinification of the feathers, suppressing its thermal decomposition. The starting milled feathers showed a halo X-ray diffraction (XRD) scattering, indicating the destruction by the milling of the four fold screw crystal structure embedded in the feather microfibrils. Fourier-transform infrared (FTIR) spectroscopic measurements revealed that the amide I peak of the pristine feathers was slightly shifted to the higher wavenumber side by milling or resinification, which means a decrease in the strength of hydrogen bonds between the adjacent β-strands. After the hot-press compression molding, a non-oriented crystalline WAXD peak was clearly recognized again, indicating the partial recrystallization of the feather keratin. The glass transition temperature of the feather keratin resin was estimated at around 120 °C from the onset of the increase of the loss modulus (E″) in the dynamic mechanical analysis (DMA) measurements. Further, it was confirmed that resinification of the milled feathers followed by the hydrothermal treatment could produce a carbonizing precursor having stacked polyaromatic carbon clusters which may be applicable to design a functional electrode. [ABSTRACT FROM AUTHOR]

The phase structures of quenched, annealed, and compression-molded samples of polypropylene/polystyrene/styrene–butadiene block copolymer (PP/PS/SB) blends were compared with the aim to elucidate the phase structure evolution during individual steps of compression molding. It was found that PS particles partitioned with SB are formed by coalescence in a hot press. Measurement of the temperature during cooling of compression-molded samples showed that a decrease of the temperature in molten PP to its crystallization temperature is fast, and coalescence during this step is small. Coalescence induced by rejection of dispersed particles from the crystallizing front of PP matrix gives a remarkable contribution to the size of PS particles in compression-molded samples. This should be considered, besides coalescence in a hot press, for description of the phase structure evolution during compression molding for all blends with a semicrystalline matrix. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the mechanical performance (tensile, bending, and impact properties) of polypropylene (PP) composites filled with betel nut (Areca catechu) short fiber (Bn) at different compositions (3, 5, 10, 20, 30wt%), using extruding and hot press moulding technique. Results showed that Bn10:PP90 mixture composite (BnPP) had better performance among the composites prepared. Because of the suitability of seaweed (Sw) as a filler in PP composite, as shown in our previous work, seaweed is subjected to hybridize with betel nut short fiber in PP composite to achieve superior mechanical performance. Water sorption capacity, degradation behavior such as simulating weathering and soil buried test of different composites were also performed. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) being the main mineral constituent of human hard tissues is highly bioactive. Good chemical bonds can be generated between HA and natural bone. However, the low strength and inherent brittleness of HA restrict its application usually to non-load-bearing conditions. In this work, production of a new kind of HA–ZrO2 composite by hot-press sintering method is described. Bioglass which has been widely used in reconstruction of damaged or diseased tissues was added into HA–ZrO2 composites. Comparing with pure HA ceramic, this type of composite possesses better mechanical strength and retains the bioactivity of HA as well. The liquid phase generated by bioglass has been effective in improving the sintering process of HA–ZrO2 composites. The phase composition of HA composite was characterized by XRD and their fracture surfaces were observed by SEM. The XRD results show that introducing a small amount of bioglass into HA–ZrO2 composite cannot enhance decomposition of HA. The SEM images show that there were fewer pores on the fracture surfaces of HA–ZrO2–bioglass composite than in the HA–ZrO2 composite. The flexural strength and toughness of HA–ZrO2 composite containing 2 wt% bioglass were 157 MPa and 1.63 MPa·m1/2, respectively. [ABSTRACT FROM AUTHOR]

PEO: IL(1-ethyl-3-methylimidazolium Tosylate) and (PEO: IL) + xAl2O3 polymer composite films have been obtained by (a) hot press and (b) solution cast techniques. The films prepared by hot press techniques give higher conductivity than their corresponding solution-casted samples. The PEO: IL polymer films conductivity has been found to increase with the amount of IL in PEO polymer matrix at a given temperature. The temperature dependence conductivity of PEO: IL films have been studied and discussed for the films prepared by two preparatory methods (a) hot press and (b) solution cast. The temperature dependence of conductivity exhibited an Arrhenius-type thermally activated behaviour. The ceramic filler Al2O3 concentration-dependent conductivity of PEO + IL (20 wt.%) film shows two conductivity maxima at 2 and 10 wt.%, respectively, which has been explained on the basis of double percolation threshold model. [ABSTRACT FROM AUTHOR]

Five group of different layering methods of basalt/carbon fiber (BF/CF) hybrid reinforced resin matrix composites are prepared by vacuum infiltration hot-press forming process. The bending properties with different layering methods have obvious distinguishing, B5C1 (B-Basalt fiber, C-Carbon fiber) has the lowest bending strength of 283 MPa, and B1C5 has the highest bending strength of 404 MPa. The observation of microstructure shows that infiltration effect of composites is good, and matrix is fully and evenly distributed in fibers. The bending fracture morphology is also relatively ideal. Some of the fibers show brittle fracture morphology and others show pull-out morphology, further indicating that the fibers are tightly bound to the matrix. In addition, the ultimate bending strength of composite single-layer plate is calculated, and the formula for calculating the bending strength of the composite laminate is established based on the laminate principle. By modifying the calculation formula, more accurate results are obtained. The experimental results are in good agreement with the theoretical ones, and the reliability of the calculation method is verified. The results showed that carbon fiber enhanced the bending strength of hybrid laminates, but with the increase of carbon fiber content, the strengthening effect decreased [ABSTRACT FROM AUTHOR]