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The main goal of this study is to improve the mechanical properties of low-alloy steels using an austempering heat treatment that involves combined molten bismuth and gallium (Bi-Ga) alloys. The cooling media is an alternative to the salt media, which is commonly used for austampering heat treatment. The steel was maintained at a constant temperature of 500 °C by immersing it in a cooling medium containing gallium and bismuth. The steel achieved an improvement of 229% in hardness and a 50% increase in tensile strength. Some slight decreases in thermal conductivity and diffusivity occurred as a result of the development of bainite in austempered steel, which affected the thermal behavior of the material. Through the process of bismuth diffusion into the steel grains, phase hardening was improved. To accomplish this, maintaining carbide stability and encouraging uniform carbon distribution were key. 500 °C was the best choice for austempering, where improved mechanical qualities were equally balanced. With its enhanced tensile strength, lightweight applications are now within reach, and the steel's enhanced hardness makes it perfect for uses requiring high durability and resistance to wear. This research emphasizes the potential of molten Bi-Ga austempering to enhance the performance of low-alloy steel across several industrial applications.

The development of transforming Belulang grass (Eleusine indica) fiber into high-value-added products has not been explored. Microcrystalline cellulose (MCC) is a promising natural material that has been widely used in several sectors. This study is focused on the MCC isolation from Belulang grass fibers using alkalization, bleaching, and acid hydrolysis. The effects of these treatments on the chemical composition, surface morphology, crystallinity, and thermal stability of the fibers were evaluated using various techniques. Fourier-transform infrared (FTIR) analysis confirmed the removal of lignin and hemicellulose content through treatments like alkalization and acid hydrolysis. Scanning electron microscopy (SEM) revealed a transformation in the fiber surface from a bundled structure to individual rods with average lengths of 15.64 μm after acid hydrolysis. Acid hydrolysis significantly increased the cellulose content by 119.2 %, while simultaneously reducing hemicellulose and lignin contents by 72.6 % and 84.1 %, respectively. X-ray diffraction (XRD) analysis demonstrated a remarkable increase in crystallinity index from 51.87 % to 75.76 % following hydrolysis. Moreover, thermogravimetric analysis (TGA) confirmed the enhanced thermal stability of MCC, with a decomposition temperature reaching up to 366.53 °C. These findings suggest that MCC derived from Belulang grass has the potential to be a sustainable alternative to synthetic materials for reinforcing biocomposites.

Sansevieria trifasciata fiber (STF) has a high cellulose content and considerable potential as a polymer composite reinforcement. This study aims to investigate the effect of alkali treatment on the physicochemical properties, tensile strength, thermal properties, and surface characteristics of STF. We explored the chemical changes in STF that had undergone alkali treatment and achieved an optimum increase in cellulose content of 51.8 % by weight. Soaking the STF for 120 minutes significantly changed its chemical composition. XRD analysis results indicated an increase in crystallinity index and fiber size by 75 % and 68 nm, respectively. After surface treatment, the density of STF increased to 1225 kg/m3, while the percentage of total weight decreased. Thermogravimetric testing provided relevant data for mechanical and thermal characteristics, including an increase in tensile strength to 535 MPa, a tensile modulus of 4.23 GPa, and thermal stability up to 371 °C. In addition, modification of the fiber surface by alkalization increased the wettability of the matrix, which in turn improved the ability of the fibers to interact with the resin. Observation of fiber morphology showed a reduction in lignin and hemicellulose content, which in turn improved the properties of the resulting composite. These results indicate that STF with optimized surface modification has the potential to be an excellent reinforcement for polymer composites.

Purun fiber (PF), which has been used as a raw material for handicrafts, can be used as a filler in composite materials. The purpose of this study is to determine the characteristics of polyester composites with the addition of PF filler at concentrations (5, 10, and 15 %) with arrangements, namely parallel, random, and woven. In this study, the method used was the press molding method with a size of 20 × 20 × 0.3 cm. The resulting composite was analyzed for functional groups, physical properties, morphological properties, mechanical properties, and thermal properties. The functional group results of PF treatment showed a sharp absorption at wave numbers 1724–2983 cm−1, indicating the presence of C=C vibrations in the aromatic ring. For all fiber arrangements, the addition of 10 % PF resulted in the best composite structure. The results of the highest composite physical properties include density, water absorption, and thickness swelling of 0.958 g/cm−3, 10.079 %, and 24.57 × 10−3, respectively. The results of the highest composite mechanical properties are tensile strength, tensile modulus, elongation, and flexural strength of 813.9519 MPa, 9345.737 MPa, 14.06 MPa, and 58.8399 MPa, respectively. While the results of the thermal properties that can be seen from the percent weight loss of the composite obtained the best results in random samples with a variation of 10 %, the effect of the PF filler ratio on composite heat flow obtained the best results, namely in samples parallel to 5 % with a temperature of 500.87 °C. It can be summarized that PF has the potential as a filler in the manufacture of composites.

Carbon-containing compositions of refractory products with additives of aluminum, silicon, graphite of fractional composition have been developed and optimized, and their technical properties, as well as the phase-mineral composition, have been determined.An experimental setup has been developed to study temperature parameters in given hypothetical layers, calculated heat fluxes and temperature stresses of carbon containing products up to 1300 °C.Temperature stresses and specific heat flows are calculated at the heating rate of the working surface from 4.3 °C/min to 55 °C/min with isothermal exposure of products at 700 °C, 950 °C and 1300 °C.This study is devoted to the technology of obtaining carbon-containing refractories by solid-state combustion method (in SHS mode) with the maximum transformation of low-melting phases into refractory ones using ferroalloy metallurgy waste, as well as to the study of thermophysical properties, composition, and influence of specific heat fluxes on temperature stresses in conditional hypothetical layers obtained carbon-containing SHS refractory products.

The influence of functionalised graphene nanoplatelets with melamine on the thermal and mechanical properties of a 3D-printed photopolymerisable resin is investigated. In this work, a liquid-based 3D printer and stereolithography were employed to fabricate the 3D-printed parts, and a commercial dimethacrylate-based resin was used. The 3D-printed parts were subjected to ultraviolet and thermal post-curing stages to improve thermal and mechanical behaviour. The quality of the graphene nanoplatelets’ functionalisation was characterised by Fourier transform infrared spectroscopy and thermogravimetric analysis. Thermal and mechanical characterisations were performed via thermogravimetric, tensile, and Izod impact tests. The fractured surfaces were observed via scanning electron microscopy. The degree of graphene nanoplatelet dispersion in the polymer matrix is enhanced by bonding with melamine via π–π interactions and inhibited surface defect formation. Results show property enhancements of up to 35% in tensile strength, 78% in impact strength, and 38% in residual weight at 400 °C.

The effects of substituting the B cation in A3BO7 ceramics on their thermal physical properties were investigated by applying a large mass difference. Y3(Nb1‐xTax)O7 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized, and their structural characteristics were determined. All the fabricated Y3(Nb1‐xTax)O7 ceramics showed defective fluorite structures and glass‐like low thermal conductivity (1.18−2.04 W/m∙K at 25°C) because of the highly distorted crystal structure and significant mass difference. Substitution with Ta5+ enhanced the sintering resistance, leading to superior thermal‐insulating performance via grain boundary scattering. Furthermore, the ceramics exhibited excellent coefficients of thermal expansion, implying the promising applicability of Y3(Nb1‐xTax)O7 as new thermal barrier materials. The effect of mass difference on the thermomechanical properties of the ceramics was examined, suggesting a simple strategy for engineering the chemical composition of new thermal barrier materials. [ABSTRACT FROM AUTHOR]

In this study, the addition of carbon nanotubes (MWCNT) and modified carbon nanotubes (MWCNT-COOH) in the range of 0.5 wt. % to 5 wt. % in polyamide (PA) obtained as a residue upon 3D printing, was investigated. PA and nanocomposite samples were prepared by melt mixing. PA/MWCNT and PA/MWCNT-COOH nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), THB thermal conductivity determination method, electrochemical impedance spectroscopy (EIS), and tensile test. Results of DSC analysis showed that both types of carbon nanotubes (MWCNTs) acted as nucleation centres of PA matrix, but had no effect on the order of the crystalline structure. Due to the polar nature of the surface and better dispersion, MWCNT-COOH filler accelerated PA crystallization more significantly compared to MWCNT. Due to the presence of nanofiller, the PA chains had limited motion space, which interfered with the crystallization process of the matrix. The thermal stability of the PA matrix increased with the addition of both MWCNT and MWCNT-COOH fillers. Higher thermal conductivity was achieved with the addition of MWCNT-COOH filler compared to the addition of MWCNT. The results of the tensile test showed that with the addition of both types of MWCNT fillers in the PA matrix, the modulus of elasticity and yield stress had reduced, but the yield strain increased. Results of the EIS showed that MWCNT nanofiller had not changed the electrical conductivity regardless of modification.

Modification of biobased PLLA properties by mixing with conventional PMMA via melt mixing in Brabender mixer was performed. Despite negative results of theoretical miscibility calculations by the group contribution approach of Coleman, Graf and Painter, homogeneous blend morphologies were prepared as recorded with scanning electron microscopy (SEM). All PLLA/PMMA blends displayed a single glass transition temperature. With increasing fraction of PMMA in blends, the increase in Tg from 58 °C to 93 °C was recorded by differential scanning calorimetry (DSC). Added PMMA improved mechanical properties, while the flexibility of PLLA/PMMA blends gradually decreased as revealed by DMA measurements.

The elastomeric materials based on NR/BR/SBR ternary rubber blend were investigated. The polyisoprene (NR), butadiene (BR) and styrene butadiene (SBR) rubbers were used as network precursors and carbon black (CB) as an active filler (60 phr) for elastomeric materials preparation. For sample preparation, the mass ratio of NR to BR was constant, 1:1, but the SBR content was varied from 0 to 80 phr. The morphological, mechanical and thermal properties of prepared elastomeric materials were determined using scanning electron microscopy (SEM), mechanical tensile measurements and thermogravimetric analysis (TGA). Mechanical properties were assessed before and after thermooxidative aging during 168 h at 100 °C. The values of tensile strength, elongation at break, and hardness decrease up to 40 phr of SBR content and after that are increasing, but abrasion resistance of ternary rubber blends increases. Тhe thermal decomposition temperature obviously shifted to a higher temperature for the sample with 40 phr of SBR. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45022 and Grant no. 45020]

Nowadays, increasing attention is devoted to the search for polymeric composite materials that are characterized by reduced flammability. In this work, the layer-by-layer (LbL) technique was applied to form multilayered protective coatings for polyamide 6/montmorillonite (PA6/MMT) hybrid nanocomposites. This time, the double layers LbL deposition was used in order to improve the thermal properties or flammability of PA6 materials. Our goal was to check how five, 10, and 15 triple-layer deposition onto the surface of PA6 and PA6/MMT composites influenced these relevant properties. For this reason, disodium H-phosphonate, sodium montmorillonite, and iodo-bis(triphenylphosphino)copper were used for polyelectrolyte solution preparation. It was found that the LbL method could be successfully used to improve the flammability characteristics of polyamide 6-based composites. Nevertheless, the deposition of the copper complex should be combined with other flame retardants—preferentially containing phosphorus—which enable synergistic effects to occur. Moreover, microscopic observations confirmed that the surfaces on which the formation of interwoven fibrous crystal structures was observed had a tendency to protect the entire material against the destructive effects of heat, contributing, among other things, to reduce the maximum point of heat release rate (PHRR). [ABSTRACT FROM AUTHOR]

A new and efficient catalyst of Na-Montmorillonite (Na+-MMT) was employed in this paper for α-methylstyrene (AMS) cationic polymerization. Maghnite clay, obtained from Tlemcen Algeria, was investigated to remove heavy metal ion from wastewater. “Maghnite-Na” is a Montmorillonite sheet silicate clay, exchanged with sodium as an efficient catalyst for cationic polymerization of many vinylic and heterocyclic monomers. The various techniques, including 1H-NMR, 13C-NMR, IR, DSC and Ubbelohde viscometer, were used to elucidate structural characteristics and thermal properties of the resulting polymers. The structure compositions of “MMT”, “H+-MMT” and “Na+-MMT” have been developed. It was found that the cationic polymerization of AMS is initiated by Na+-MMT at 0 °C in bulk and in solution. The influences of reaction temperature, solvent, weight ratio of initiator/monomer and reaction time on the yield of monomer and the molecular weight are investigated. The kinetics indicated that the polymerization rate is first order with respect to the monomer concentration. A possible mechanism of this cationic polymerization is discussed based on the results of the 1H-NMR Spectroscopic analysis of these model reactions. A cationic mechanism for the reaction was proposed. From the mechanism studies, it was showed that monomer was inserted into the growing chains.

Nucleophilic substitution on hexachlorocyclotriphosphazene (HCCTP) with allylamine in order to give hexa(allylamino)cyclotriphosphazene (HACTP) is performed for the first time under mild conditions by using diethylether as solvent to replace benzene which is very toxic. The reaction time is reduced to half and also performed at room temperature but especially in the presence of an eco-catalyst called Maghnite-H+. This catalyst has a significant role in the industrial scale. In fact, the use of Maghnite is preferred for its many advantages: a very low purchase price compared to other catalysts, the easy removal of the reaction mixture. Then, Maghnite-H+ is became an excellent catalyst for many chemical reactions. The structure of HACTP synthesized in the presence of Maghnite-H+ to 5% by weight is confirmed by 1H-NMR, 13C-NMR, 31P-NMR (Nuclear magnetic resonance) and FTIR (Fourier Transform Infrared spectroscopy). MALDI-TOF (Matrix-Assisted Laser Desorption/Ionisation-time-of-flight mass spectrometry) is used to establish the molecular weight of HACTP which is 471 g/mol. DSC (Differential Scanning Calorimetery) and TGA (Thermogravimetric Analysis) show that HACTP is a crystalline product with a melting point of 88 °C. It is reactive after melting but is degraded from 230 °C.

Polycaprolactone (PCL) and poly(butylene terephthalate) (PBT) blend was prepared by melt processing. The PCL/PBT blend showed similar morphology with that of pure PCL.The crystallization temperature of PCL was increased by the incorporation of PBT. It was also observed that the peak height in the DSC thermograms decreased and then disappeared by adding 40 % or more PBT which might be due to the transestrification between –OH end groups of PCL and ester groups of PBT. The size of PCL spherulites was about 13 µm which decreased highly in the case of blends due to the nucleation effect. The thermal stability of the PCL/PBT blend was higher than pure PCL.

Biodegradable polymer blends prepared by blending poly(3-hydroxybutyrate) (PHB) and corn starch do not form intact films due to their incompatibility and brittle behavior. For improving their compatibility and flexibility, poly(vinyl acetate) (PVAc) was grafted from the corn starch to prepare the PVAc-modified corn starch (CSV). The resulting CSV consisted of 47.2 wt% starch- g-PVAc copolymer and 52.8 wt% PVAc homopolymer and its structure was verified by FT-IR analysis. In comparison with 35°C of the neat PVAc, the glass transition temperature ( Tg) of the grafted PVAc chains on starch- g-PVAc was higher at 44°C because of the hindered molecular mobility imposed from starch on the grafted PVAc. After blending PHB with the CSV, structure and thermal properties of the blends were investigated. Only a single Tg was found for all the PHB/CSV blends and increased with increasing the CSV content. The Tg-composition dependence of the PHB/CSV blends was well-fitted with the Gordon-Taylor equation, indicating that the CSV was compatible with the PHB. In addition, the presence of the CSV could raise the thermal stability of the PHB component. It was also found that the presence of the PHB and PVAc components would not hinder the enzymatic degradation of the corn starch by α-amylase. POLYM. ENG. SCI., 55:1321-1329, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

New oleogel formulations based on high-oleic sunflower oil (HOSO) and ethylene vinyl acetate copolymer (EVA)/polypropylene (PP) blends were prepared using the mixing rheometry technique and further characterized. The effects of PP tacticity and EVA vinyl acetate (VAc) content on the rheological, morphological, and thermal behavior of derived oleogels were investigated. Differential scanning calorimetry (DSC) and polarized-light optical microscopy (PLOM) observations indicated that VAc segments markedly influence the crystalline structure of polymeric fractions and phase morphology of oleogels. The normalized crystallinity of isotactic polypropylene (iPP) phase increased linearly with its concentration whereas syndiotactic polypropylene (sPP) content does not exert a significant influence. PLOM observations showed that VAc content plays an important role in the phase morphology of PP frictions (size and shape of crystals). The viscoelastic response of oleogels depended on PP tacticity and VAc content, which may be explained attending to the different microstructures attained. POLYM. ENG. SCI., 55:1429-1440, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

To study the relation between cold-hot-water mixing ratio and outlet-water temperature of a mixer, the geometrical model of the mixer was built. On the basis of theoretical analysis, the outlet-water temperature with different mixing ratio of cold and hot water was simulated by FLUENT software. The results show that: flow field in mixer can be divided into recirculation zone and convection zone, in which there are different thermal resistances individually, and it result in the nonlinear relation in outlet average temperature and mixing ratio; there is a linear relation between outlet average velocity and mixing ratio, which accords to the mass conservation principle of non-compressible and continuous fluid flow. [ABSTRACT FROM AUTHOR]

Polycarbonate-based polyurethane (PC-PU) nanostructured composites were obtained using a one-step technique, by the addition of 1 wt.% organically modified clays (either bentonite or montmorillonite). Only aliphatic components (polycarbonate diol, hexamethylene-diisocyanate and 1,4-butane diol) were used as reactants. The hard segment content of the obtained polyurethanes was 30 wt.%. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) were performed to investigate the morphology and hydrogen bonding formation in prepared elastomers. The influence of nanofiller addition on thermal properties of PC-PUs was studied using differential scanning calorimetry (DSC). The degree of phase separation of polyurethane nanocomposites was not influenced by the dispersion of silicate layers in the elastomeric matrix. It was determined that bentonite and montmorillonite affect the melting transition of hard segments and the recrystallization process, which is very important for the processing and recycling of the prepared polyurethane hybrid materials.

Abstract: The knowledge of thermal properties of technical components or internals in chemical reactors is often a key characteristic for planning and designing chemical engineering processes. As an alternative to packed beds or packings, sponges turned out to be used in new application fields in chemical and process engineering. Therefore an experimental study was performed to investigate the two-phase thermal conductivity of solid ceramic sponges made of alumina, mullite and oxidic-bonded silicon carbide (OBSiC) at moderate temperatures. A two-dimensional model is used for analysing the measured temperature profiles and for calculating the thermal conductivity. It can be observed, that the thermal conductivity increases with decreasing porosity and is nearly constant when the pore size (ppi number) is varied. The thermal conductivity data are modelled by an approach similar to the well known Krischer model. Compared to a packed bed of spherical particles, the values of the thermal conductivity of sponges turn out to be about five times higher. [Copyright &y& Elsevier]

Abstract: According to the fact that long-term excess-standard CO in low-to-medium metamorpic grade coal seams has not caused coal spontaneous ignition, this paper has carried out the experimental research on adsorption test of eight typical coal samples with different maceral compositions on CO under different pressures. Comprehensive thermodynamic studies on the corrected adsorption volume were conducted by applying physical chemistry, interface chemistry, coal petrology and coal chemical engineering knowledge. Adsorptivity was evaluated from three aspects, including specific surface area, adsorption capacity on per surface area, and interaction between CO molecule and coal surface. The results show that the adsorption of inertinite is better than that of vitrainite. The change rule in free energy of coal surface under different balance conditions shows that the surface free energy of coal samples with higher vitrinite content is greater than that with higher inertinite content. This explais the main reason why the inertinite has a better adsorption. The isosteric heat of coal samples with higher inertinite content is greater than that with higher vitrinite content and the interaction between CO molecular and coal morphology in coal samples with higher inertinite is greater than that with higher vitrinite. [Copyright &y& Elsevier]

The article provides information on measuring temperature correctly. According to the author, temperature can be accurately measured by making sure of a proper specification, installation and operation of the temperature-measurement sensor. He cited ways to improve accuracy which include determining the level of accuracy, choosing of sensor for the achievement of accuracy and the consideration of sensors that are of quality and tough construction. Other information related to the accurate measurement of temperature are also mentioned.

The article presents a study on the effect of fill factor in the use of a batch mixer in a nanocomposite preparation. It is also stated that in comparing samples a quantitative measurement of the degree of mixing is expected. TEM particle density, skewness, and Morisita's index are statistical analysis techniques which are based on the particle counting that were used to the alumina/polyethylene terephthalate (PET) nanocomposites. DSC was used to measure nonisothermally the thermal properties and the percent of crystallinity. The article also states that TEM particle density and skewness are both useful techniques, but skewness from quadrat method was found to be the most suitable method to determine the degree of mixing in nanocomposites.

Abstract: Many fibrous materials such as nonwoven materials are often consolidated by means of hot calenders, i.e., hot compaction rolls. Hot calendering compresses the fiber assembly and can cause changes in the structure. In nonwovens, calendering has an added function of thermally bonding the fibers at their respective crossovers to form a strong but yet somewhat porous material. Calendering causes a significant increase in the solid volume fraction (SVF) of the media and therefore, affects their permeability. To our knowledge, no work in the literature has been dedicated to modeling the permeability of calendered nonwovens. In this study, virtual nonwoven structures are generated and compressed from top and bottom to resemble the hot calendering process. In agreement with our experimental observations, it was found that the average SVF profile across the material''s thickness turns into a U-shape profile after the calendering. In this work, the dimensionless permeability of the calendered media is computed using CFD tools and reported for different compaction ratios. Results of our simulations are compared with the experiment as well as the available empirical and/or analytical permeability models in the literature and good agreement, depending upon the SVF, is observed. We also studied the influence of orientation distribution of the fibers on the dimensionless permeability of the fabric and noticed that permeability decreases by increasing the directionality of the fibers. This is found to be primarily due to the fact that highly oriented uncompressed fiber-webs tend to have a higher SVF. Fiber-webs of identical SVF, however, exhibited almost identical permeabilities regardless of their fiber orientations. [Copyright &y& Elsevier]

The article presents polymer engineering research into the effects of a tert-butylphenylene substituent on the thermal, fluorescent, optical, and structural properties of the poly(p-phenylenevinylene) derivatives. Poly(2-decyloxy-5-(4'-tert-butylphenyl)-1,4-phenylenevinylene (DtBP-PPV) and poly(2-decyloxy-1,4-phenylenevinylene) (DO-PPV) are soluble fluorescent polymers that were prepared by a procedure that bears similarities to the Gilch method. Thermogravimetric analysis, electroluminescence spectroscopies, and deuteron magnetic resonance spectroscopy were used to characterize the polymers.