Papers by Keyword: Thermal Property

Abstract: The harmonic structure composites with Ti-Ni alloy and Cu were fabricated by mechanical milling (MM) / spark plasma sintering (SPS) process and were investigated mechanical and thermal properties in detail. Fine Ti-Ni alloy powder and coarse Cu powder were mechanically milled using planetary ball mill equipment at cryogenic temperature. The MM powder was sintered by using the SPS apparatus at 1073 to 1273 K. Tensile tests carried out at 383 K as mechanical properties evaluation. Thermal expansion to 1073 K was evaluated using thermomechanical analyzer equipment. Microstructural observation of the MM powders and SPS compacts was achieved using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SPS compacts is the harmonic structure composite having the network structure with Ti-Ni alloy and the dispersive area with Cu. Such a Ti-Ni/Cu harmonic structure composite exhibits unique mechanical properties. T ensile strength and elongation increase with increasing the sintering temperature in the Ti-Ni/Cu harmonic structure composite. The coefficient of linear thermal expansion of the Ti-Ni/Cu harmonic structure composite lies between that of Ti-Ni alloy and Cu, and a sufficient reduction in the coefficient of linear thermal expansion is confirmed.

Abstract: Oil palm empty fruit bunches (OPEFB) are wastes from oil palm processing. The objective of this work is to study the effect of composition on the physical, mechanical, and thermal properties of OPEFB epoxy resin biocomposite. Particles of OPEFB (100 mesh) were mixed with epoxy resin with the ratio of OPEFB to epoxy resin 60/40, 70/30, 80/20, and 90/10 (vol.%/vol.%). Biocomposites were produced by a press method at room temperature with 9 tons-load. The physical properties (density, porosity, water absorption, thickness swelling) of the biocomposite were evaluated. The mechanical properties (modulus of rupture and modulus of elasticity) of biocomposite were determined by using a universal testing machine. The thermal gravimetric analyzer (TGA) was used to examine the thermal properties of the biocomposite. The results show that the density of biocomposite is 1.18 g/cm³ for 60 vol.% of OPEFB composition. It decreases significantly as the OPEFB composition increases. For 60 vol.% of OPEFB, the porosity, water absorption, and thickness swelling of biocomposite (after soaking in water for 24 hours) are 11.9%, 10.1%, and 6.5%, respectively. All these values increase significantly with the increase of OPEFB composition. For 60 vol.% of OPEFB, the modulus of rupture (MOR) and modulus of elasticity (MOE) of biocomposite are 2.31 kgf/mm² and 267 kgf/mm², respectively. The values of MOR and MOE decrease significantly with the increase in OPEFB composition. TGA results show that degradation of biocomposites occurs significantly at 350°C for 60 vol.% OPEFB. The degradation temperature reduces as the composition of OPEFB increases. In general, the physical, mechanical, and thermal properties of biocomposites decrease with increasing OPEFB composition. This happens because the bond between the matrix and the particles decreases as the OPEFB composition increases. The maximum OPEFB composition that can be used for particleboard applications is 80 vol.%, which meet the ANSI 208.1-2009 requirements for application as grade M-2 particleboard.

Abstract: The sepiolite and Al₂O₃-doped sepiolite contents in the as-received sepiolite/epoxy systems were maintained at 2 and 4wt %, respectively. The flame-retardant capabilities and combustion behavior of Al₂O₃-doped sepiolite in epoxy resin were meticulously evaluated through a series of tests including cone calorimetry (CC), limiting oxygen index (LOI), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). Several features, including degradation kinetics, combustion characteristics, thermomechanical properties, flame retardancy, and thermal degradation were evaluated with the intention of drawing comparisons to standard sepiolite. The findings from the studies were positive. In contrast, Al₂O₃-doped sepiolite not only further improved the LOI values and char formation post-cone testing but also decreased the previously mentioned combustion-related parameters in the composites. A potential synergistic interaction between sepiolite and Al₂O₃ in augmenting the flame retardancy of the composite was suggested. The thermal degradation of composites was only little affected by addition of sepiolite, although Al₂O₃-doped sepiolite addition seemed to speed up the deterioration process. The epoxy composite’s glass transition temperature (Tg) was shown to increase when sepiolite or Al₂O₃-doped sepiolite was added, as determined by DMA. The findings presented in this research provided a practical approach to improving the fireproofing of polymers. Keywords: Al2O3-doped sepiolite; TGA, flame retardancy; DSC, epoxy; thermal properties.

Abstract: Open-cell type aluminum foam possesses unique structural characteristics comprising numerous interconnected pores within. This intriguing structure facilitates the passage of fluids (gas or liquid) through the interior of the open-cell type aluminum foams, enabling easy transfer to the exterior. The objective of this study is to manufacture open-cell type aluminum foams with varying pore sizes using the replication casting process and to evaluate their thermal properties. The equipment designed for the production of open-cell type aluminum foams consists of a chamber and an inner container. The chamber is connected to a vacuum line and an Ar gas line, with the container positioned inside. The aluminum alloys utilized for the foams were A356 and ADC12, and Na2CO3 served as the space holder. As a result of manufacturing the foams, there was no significant difference of porosity with space holder size and alloy types, the porosity averaged around 62%. To investigate the thermal properties of open-cell type aluminum foams in relation to pore size and alloy types, temperature variations were measured during sample heating via the hot plate method. Consequently, it was confirmed that the thermal properties of the foams were influenced by the structural conditions and alloy types.

Abstract: Three polyethylene glycol propargyl ethers (PGPEs), namely 4,7,10-trioxatrideca-1,12-diyne (TOTDY), 4,7,10,13-tetraoxahexadeca-1,15-diyne (TOHDY) and 4,7,10,13,16-pentaoxanonadeca-1,18-diyne (TONDY) were designed and successfully synthesized as curing agents for glycidyl azide polymer (GAP). Their structures were characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis, and their glass transition temperatures (Tg) were measured by DSC. The films of GAP cured by the title compounds were prepared via 1,3 dipolar cycloaddition, and then the influences of PGPEs on the Tg, decomposition temperature (Td) and mechanical properties of the films were studied accordingly. The results showed that the Tg of GAP cured by TOTDY and TOHDY were-38.1 oC and-38.2 oC, respectively. The Td of GAP cured by PGPEs was in the range of 235.5 oC - 241.0 oC. The results of tensile tests showed that the maximum stress of GAP films cured with PGPEs were in the range of 0.11 MPa to 0.52 MPa at elongation from 29% to 48%. These results indicated that PGPEs would have potential application in GAP based high energy solid propellant formulations.

Abstract: Recently cold spray coating technology was used for many applications in petrochemical business especially for high temperature required section. For this reason, the applied coating must be able to withstand at least 800 °C. The developed Ni/Cr cold spray coating was studied mainly on high temperature resistant property. Ni/Cr with the ratio of 80/20 feedstock powders revealed the highest deposition efficiency and it was selected to use as optimum feedstock powder compositions for the less of experimental study. Finally, it was found that Ni/Cr cold spray coatings reveal excellent thermal stability performance after completed both corrosion and thermal shock tests.

Abstract: The objectives of this work are to prepare keratin/egg white blend particles by emulsification solvent diffusion method and characterize their properties. The different factors including concentration, water: oil phases, spinning rate, and blending ratio were optimized. The morphological observation indicated that the shapes and sizes of particles were variable by the condition used. FTIR spectra indicated that all particles co-existed of α-helix and random coil structures. The decomposition rate of all particles found at least 4 steps and the blend particles have lower Td, max than the native protein particles. The obtained results were advantaged for the development of the keratin/egg white blend particles for specific applications such as drug-controlled release systems.

Abstract: In this paper, the effect of nanoTiO₂ content on the thermal properties, mechanical properties, photocatalytic properties of PA6/TiO₂-GO composites were investigated. The results indicated that the melting point of the composites decreased gradually with an increase of nanoTiO₂ content, and the degree of crystallinity exhibited an increasing trend at first and then tended to decrease. Meanwhile, the breaking strength decreased gradually, whereas the elongation at break increased gradually. Moreover, the nanoTiO₂ exhibited an increasing photocatalytic activity for degradation of the methylene blue solution. The incorporation of graphene oxide (GO) could effectively improve the photocatalytic effectiveness of nanoTiO₂ by approximately 11%.

Abstract: Natural rubber is an elastomeric material to make rubber products such as toys, households, automobiles, wheel tires, medical and health care products. Natural rubber compound is one kind of polymer matrix composites (PMCs) composed of natural rubber compound acted as a matrix phase and filler acted as a dispersed or reinforcement phase. There are many kinds of fillers used in the PMCs in terms of particles, fibers, and structural sheets. Adding organic/inorganic fibers into the natural rubber composites can increase the mechanical-thermal-physical properties and sound absorption. The natural rubber embedded fiber composite samples were prepared via the vulcanization process at the curing temperature 150°C by the two-roll mill. The amount of whisker alumina (Al₂O₃), coconut coir and water hyacinth fiber were varied from 0 to 50 phr on 100 phr of natural rubber in a sulfur curing system. The obtained rubber composite samples were of good mechanical properties, low thermal conductivity and good acoustic-sound absorption, suitable for various applications such as automobile, insulation and storage tank. The obtained rubber composite with 10 phr whisker alumina added (NR-Al-10) possessed the tensile strength, Young’s modulus, elongation at break and thermal conductivity values equal to 14.38 ± 1.95 MPa, 545.63 ± 25.67 MPa, 1038.4 ± 41.45% and 0.02527 ± 0.0003 W/m.K, respectively. Furthermore, the sound absorption value of natural rubber composite added 10 phr whisker alumina (NR-Al-10) is equal to 45.09% in the range of 3000‒4000 Hz of acoustic sound level better than the pure natural compound without adding filler.

Abstract: Epoxy resin composites filled with alumina (Al₂O₃) particles of different morphology and content were fabricated by vacuum casting method. Electric and thermal properties of the composites were tested at room temperature to investigate the influence of Al₂O₃ morphology on epoxy resin composites. Electrical tests demonstrated that, volume resistivity of epoxy resin composites filled with spherical Al₂O₃ was bigger than with spherical-like Al₂O₃, relative permittivity and dielectric loss of epoxy resin composites increased with increasing of Al₂O₃ content, the effect on dielectric properties of spherical-like Al₂O₃, which had larger specific surface areas, was larger than spherical Al₂O₃ for the same content of filler. Thermal conductivity tests proved that, at the same content, thermal conductivity of epoxy resin composites filled with spherical-like Al₂O₃ was higher than with spherical Al₂O₃. According to the Agari model, spherical-like Al₂O₃ particles were easier to form conducting pathways in epoxy resin composites than spherical Al₂O₃ particles, considering their matte edges.