Search Results (1,366)

In this study, a series of copolymers was synthesized using the promising biodegradable polymers Poly(L-lactic acid) (PLLA), Poly(lactic-co-glycolic acid) (PLGA), and Poly(ethylene adipate) (PEAd), known for their high potential. PEAd was synthesized through a two-step melt polycondensation process and then used to prepare copolymers with PLLA (PLLA-co-PEAd) and PLGA (PLGA-co-PEAd) at weight ratios of 90/10 and 75/25, respectively. The synthesized materials, along with the starting polymers, were extensively characterized for their structure, molecular weight, crystallinity, and thermal behavior. These novel systems exhibit single thermal transitions, e.g., glass transition. The incorporation of PEAd into the copolymers induced a plasticizing effect, evidenced by a consistent decrease in the glass transition temperature. Due to the latter effect in combination with the M_w drop, the facilitation of crystal nucleation was observed. Finally, the results by dielectric spectroscopy on the local and segmental molecular mobility provided additional proof for the homogeneity of the systems, as manifested, e.g., by the recording of single segmental relaxation processes. Overall, the findings indicate that the PLLA-co-PEAd and PLGA-co-PEAd copolymers hold significant potential, and the use of complementary experimental techniques offers valuable insights and indirect indications of their properties. Full article

Ternary choline chloride-based deep eutectic solvents (TDESs) exhibit unique physicochemical properties, including lower viscosities, lower melting points, higher thermal stabilities, and enhanced solvations compared to binary deep eutectic solvents (BDESs). Although BDESs have been widely studied, the addition of a third component in TDESs offers opportunities to further optimize their performance. This review aims to evaluate the physicochemical properties of TDESs and highlight their potential applications in sustainable industrial processes compared to BDESs. A comprehensive analysis of the existing literature was conducted, focusing on TDES properties, such as phase behavior, density, viscosity, pH, conductivity, and the effect of water, along with their applications in various fields. TDESs demonstrated superior physicochemical characteristics compared to BDESs, including improved solvation and thermal stability. Their applications in biomass conversion, CO₂ capture, heavy oil upgrading, refrigeration gases, and as solvents/catalysts in organic reactions show significant promise for enhancing process efficiency and sustainability. Despite their advantages, TDESs face challenges including limited predictive models, potential instability under certain conditions, and scalability hurdles. Overall, TDESs offer significant potential for advancing sustainable and efficient chemical processes for industrial applications. Full article

This study synthesized FeNiCuAlX high-entropy alloys (HEAs) (where X = Cr, Co, Mn) using arc melting and investigated their high-temperature oxidation behavior in air at 900 °C. The oxidation kinetics of all alloys followed a parabolic rate, with the oxidation rate constants (kp) of FeNiCuAlCr, FeNiCuAlCo, and FeNiCuAlMn being approximately two to three orders of magnitude lower than that of the FeNiCu alloy. Specifically, FeNiCuAlCr exhibited the lowest kp value of 1.72 × 10⁻⁶ mg²·cm⁴/s, which is significantly lower than those of FeNiCuAlCo (3.29 × 10⁻⁶ mg²·cm⁴/s) and FeNiCuAlMn (1.71 × 10⁻⁵ mg²·cm⁴/s). This suggests that the addition of chromium promotes the formation of a dense Al₂O₃/Cr₂O₃ oxide layer, significantly enhancing the oxidation resistance. Furthermore, corrosion resistance was assessed through potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. FeNiCuAlCr demonstrated exceptional resistance to localized corrosion, as indicated by its low corrosion current density (45.7 μA/cm²) and high pitting potential (−0.21 V), highlighting its superior corrosion performance. Full article

In the present work, the optimization of ceramic-based composite WC(Co,Ni) welds by laser cladding was carried out using response surface methodology based on finite element analysis. The heat distribution and temperature field of laser-melted WC(Co,Ni) ceramic coatings were simulated using ANSYS software, which allowed the computation of the distribution of residual stresses. The results show that the isotherms in the simulation of the temperature field are elliptical in shape, and that the isotherms in front of the moving heat source are dense with a larger temperature gradient, while the isotherms behind the heat source are sparse with a smaller temperature gradient. In addition, the observed microstructural evolution shows that the melting zone domains of WC(Co,Ni) are mainly composed of unmelted carbides. These carbides are dendritic, rod-like, leaf-like, or net-like, and are agglomerated into smaller groups. The W content of these unmelted carbides exceeds 80%, while the C content is around 1.5–3.0%. The grey areas are composed of WC, Co and Ni compounds. Based on the regression model, a quadratic model was successfully constructed. A three-dimensional profile model of the residual stress behaviour was further explored. The estimated values of the RSM-based FEA model for residual stress are very similar to the actual results, which shows that the model is effective in reducing residual stress by laser cladding. Full article

Steel is an important product in many engineering sectors; however, steelmaking remains one of the largest ${\mathrm{CO}}_2$ emitters. Therefore, new governmental policies drive the steelmaking industry toward a cleaner and more sustainable operation such as the gas-based direct reduction–electric arc furnace process. To become carbon neutral, utilizing more scrap is one of the feasible solutions to achieve this goal. Addressing knowledge gaps regarding scrap heterogeneity (size, shape, and composition) is essential to evaluate the effects of increased scrap ratios in basic oxygen furnace (BOF) operations. This review systematically examines heat and mass transfer correlations relevant to scrap melting in BOF steelmaking, with a focus on low Prandtl number fluids (thick thermal boundary layer) and dense particulate systems. Notably, a majority of these correlations are designed for fluids with high Prandtl numbers. Even for the ones tailored for low Prandtl, they lack the introduction of the porosity effect which alters the melting behavior in such high temperature systems. The review is divided into two parts. First, it surveys heat transfer correlations for single elements (rods, spheres, and prisms) under natural and forced convection, emphasizing their role in predicting melting rates and estimating maximum shell size. Second, it introduces three numerical modeling approaches, highlighting that the computational fluid dynamics–discrete element method (CFD–DEM) offers flexibility in modeling diverse scrap geometries and contact interactions while being computationally less demanding than particle-resolved direct numerical simulation (PR-DNS). Nevertheless, the review identifies a critical gap: no current CFD–DEM framework simultaneously captures shell formation (particle growth) and non-isotropic scrap melting (particle shrinkage), underscoring the need for improved multiphase models to enhance BOF operation. Full article

Biodegradable polymers offer environmental advantages compared to fossil-based alternatives, but they currently lack the stretchability required for demanding applications such as mesh fabrics for woven flexible intermediate bulk container (FIBC) bags and stretch, shrink, and cling films. The goal of this research is to enhance the stretchability of biodegradable blends based on 80% poly(butylene adipate-co-terephthalate) (PBAT) and 20% poly(lactic acid) (PLA) through reactive extrusion. Radical initiator (dicumyl peroxide (DCP)) and chain extenders (maleic anhydride (MA), glycidyl methacrylate (GMA)) were employed to improve the melt strength and elasticity of the extruded films. The reactive blends were initially prepared using a batch mixer and subsequently compounded in a twin-screw extruder. Films were produced via cast extrusion. 0.1% wt. DCP led to a 200% increase in elongation at break and a 44% improvement in tensile strength. Differential scanning calorimetry and scanning electron microscopy revealed enhanced miscibility between components. Shear and complex viscosity increased by 38% and 85%, compared to the neat blend, respectively. Reactive extrusion led to a better dispersion and distribution of the phases. An improved interfacial adhesion between the phases, in addition to higher molecular weight, led to enhanced melt strength and improved stretchability. Full article

The growing demand for rare-earth magnets has raised concerns over their price and the country’s risk of depleting the supply of rare-earth elements. These severe concerns have led to the study of rare-earth-free magnets that do not rely on rare-earth elements. Co-Zr-Mo-B alloys, one of the prospective candidates for rare-earth-free magnets, were produced by the melt-spinning technique and subsequent annealing. It was found that a small substitution of Mo for Zr in the Co-Zr-B alloys increased coercivity. The Co-Zr-Mo-B alloy with a Mo content of 2 at% showed a high coercivity of 6.2 kOe with a remanence of 40 emu/g. SEM studies showed that the annealed Co-Zr-Mo-B alloys had fine, uniform grains with an average diameter of about 0.6 μm. Further studies using STEM demonstrated that the ferromagnetic phase in the annealed Co-Zr-Mo-B alloys with high coercivity was composed of the Co₅Zr phase and the long-period stacking ordered (LPSO) phase. That is, the fine grains observed in the SEM studies were found to be ferromagnetic dendrites containing numerous twin boundaries of the Co₅Zr phase and its derived LPSO phase. Therefore, the high coercivity of the Co-Zr-Mo-B alloys can be attributed to the presence of ferromagnetic crystals of Co₅Zr and the derived LPSO phase. Full article

In recent years, Ga-based liquid metals have emerged as a prominent research focus in catalysis, owing to their unique properties, including fluidity, low melting point, high thermal and electrical conductivity, and tunable surface characteristics. This review summarizes the synthesis strategies for Ga-based liquid metal catalysts, with a focus on recent advances in their applications across electrocatalysis, thermal catalysis, photocatalysis, and related fields. In electrocatalysis, these catalysts exhibit potential for reactions such as electrocatalytic CO₂ reduction, electrocatalytic ammonia synthesis, electrocatalytic hydrogen production, and the electrocatalytic oxidation of alcohols. As to thermal catalysis, these catalysts are employed in processes such as alkane dehydrogenation, selective hydrogenation, thermocatalytic CO₂ reduction, thermocatalytic ammonia synthesis, and thermocatalytic plastic degradation. In photocatalysis, they can be used in other photocatalytic reactions such as organic matter degradation and overall water splitting. Furthermore, Ga-based liquid metal catalysts also exhibit distinct advantages in catalytic reactions within battery systems and mechano-driven catalysis, offering innovative concepts and technical pathways for developing novel catalytic systems. Finally, this review discusses the current challenges and future prospects in Ga-based liquid metal catalysis. Full article

The synthesis of bioplastics from renewable resources is essential for green living. PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is a biodegradable and biocompatible material ideal for various industrial applications. The impact of levulinic (LA), valeric acids (VA), and sodium propionate (SPr) as co-substrates in biomass and the synthesis of 3-hydroxy valerate (3HV) and co-polymerization of PHBV by Burkholderia thailandensis E264 (BtE264) was assessed. Thermogravimetric, XRD, NMR, and mechanical characterization were performed on the homopolymer (PHB) and co-polymer (PHBV), and compared to the PHBV-STD. BtE264 produced the co-polymer PHBV when adding any of the three co-substrates. LA showed a higher positive effect on microbial growth (8.4 g∙L⁻¹) and PHBV production (3.91 g∙L⁻¹), representing 78 and 22 mol % of 3HB and 3HV, respectively. The PHBV obtained with LA had a melting temperature (Tm) lower than the PHB homopolymer and presented lower values for melting enthalpies (ΔHf); the degree of crystallization and TGA values indicated that PHBV had better thermal stability. Additionally, FTIR and NMR revealed that BtE264 synthesizes PHBV with an organization in monomeric units (3HB-3HV), suggesting differentiated incorporation of the monomers, improving 3.4 times the break elongation the co-polymer’s tensile properties. This study highlights the co-substrates’ relevance in PHBV synthesis using BtE264 for the first time. Full article

Background/Objectives: Hot-melt extrusion (HME) has gained prominence for the manufacture of sustained-release oral dosage forms, yet the application of wax-based matrices and their resilience to alcohol-induced dose dumping (AIDD) remains underexplored. This study aimed to develop and characterise wax-based sustained-release felodipine formulations, with a particular focus on excipient functionality and robustness against AIDD. Methods: Felodipine sustained-release formulations were prepared via HME using Syncrowax HGLC as a thermally processable wax matrix. Microcrystalline cellulose (MCC) and lactose monohydrate were incorporated as functional fillers and processing aids. The influence of wax content and filler type on mechanical properties, wettability, and drug release behaviour was systematically evaluated. Ethanol susceptibility testing was conducted under simulated co-ingestion conditions (4%, 20%, and 40% v/v ethanol) to assess AIDD risk. Results: MCC-containing tablets demonstrated superior sustained-release characteristics over 24 h, showing better wettability and disintegration. In contrast, tablets formulated with lactose monohydrate remained structurally intact during dissolution, overly restricting drug release. This limitation was effectively addressed through granulation, where reduced particle size significantly improved surface accessibility, with 0.5–1 mm granules achieving a satisfactory release profile. Ethanol susceptibility testing revealed divergent behaviours between the two filler systems. Unexpectedly, MCC-containing tablets showed suppressed drug release in ethanolic media, likely resulting from inhibitory effect of ethanol on filler swelling and disintegration. Conversely, formulations containing lactose monohydrate retained their release performance in up to 20% v/v ethanol, with only high concentrations (40% v/v) compromising matrix drug-retaining functionality and leading to remarkably increased drug release. Conclusions: This study highlights the pivotal role of excipient type and constitutional ratios in engineering wax-based sustained-release formulations. It further contributes to the understanding of AIDD risk through in vitro assessment and offers a rational design strategy for robust, alcohol-resistant oral delivery systems for felodipine. Full article

In order to increase the toughness of poly(hexamethylene furandicarboxylate) (PHF) without severely compromising its strength at break, novel biobased poly(hexamethylene furandicarboxylate-co-hexamethylene thiophenedicarboxylate) (PHFTh) copolyesters and their parent homopolyesters, PHF and poly(hexamethylene thiophenedicarboxylate), were successfully synthesized through melt polycondensation in this research. Despite the variation in their compositions, all the PHFTh copolyesters exhibited excellent thermal stability. The PHFTh copolyesters were semicrystalline in nature, showing the lowest eutectic melting points and isodimorphism behaviors over the whole composition range. As the hexamethylene thiophenedicarboxylate (HTh) unit content increased, the glass transition temperature of the copolyesters gradually decreased, while the chain mobility was accordingly enhanced. Therefore, the introduction of the HTh unit significantly increased the elongation at break of the PHFTh, achieving a balance between strength and toughness. The biobased PHFTh copolyesters showed tunable thermal behaviors and excellent mechanical properties and may find potential end uses from a practical application viewpoint. Full article

This study systematically investigates the impact of hydrolytic degradation on the crystallization kinetics and morphology of poly(butylene succinate-co-adipate) (PBSA). Gel Permeation Chromatography (GPC) confirmed extensive chain scission, significantly reducing the polymer’s weight-average molecular weight (M_w from ~103,000 to ~16,000 g/mol) and broadening its polydispersity index (PDI from ~2 to 7 after 64 days). Differential scanning calorimetry (DSC) analysis revealed that hydrolytic degradation dramatically accelerated crystallization rates, reducing crystallization time roughly 10-fold (e.g., from ~3000 s to ~300 s), and crystallinity increased from 34% to 63%. Multiple melting peaks suggested the presence of lamellae with varying thicknesses, consistent with the Gibbs–Thomson equation. Isothermal crystallization kinetics were evaluated using the Avrami equation (with n ≈ 3), reciprocal half-time of crystallization, and a novel inflection point slope method, all confirming accelerated crystallization; for instance, the slope increased from 0.00517 to 0.05203. Polarized optical microscopy (POM) revealed evolving spherulite morphologies, including hexagonal and flower-like dendritic spherulites with diamond-shape ends, while wide-angle X-ray diffraction (WAXD) showed a crystallization range shift to higher temperatures (e.g., from 72–61 °C to 82–71 °C) and a 14% increase in crystallite diameter, aligning with increased melting point and lamellar thickness and overall increased crystallinity. Full article

The decarbonization of residential cooling systems requires innovative solutions to overcome the mismatch between the renewable energy availability and demand. Integrating latent thermal energy storage (LTES) with heat pump/air conditioning (HP/AC) units can help balance energy use and enhance efficiency. However, the dynamic behavior of such integrated systems, particularly under low-load conditions, remains underexplored. This study investigates a 5 kW HP/AC unit coupled with an 18 kWh LTES system using a bio-based Phase Change Material (PCM) with a melting temperature of 9 °C. Two configurations were tested: charging the LTES using either a thermostatic bath or the HP/AC unit. Key parameters such as the stored energy, temperature distribution, and cooling capacity were analyzed. The results show that, under identical conditions (2 °C inlet temperature, 16 L/min flow rate), the energy stored using the HP/AC unit was only 6.3% lower than with the thermostatic bath. Nevertheless, significant cooling capacity fluctuations occurred with the HP/AC unit due to compressor modulation and anti-frost cycles. The compressor frequency varied from 75 Hz to 25 Hz, and inefficient on-off cycling appeared in the final phase, when the power demand dropped below 1 kW. These findings highlight the importance of integrated system design and control strategies. A co-optimized HP/AC–LTES setup is essential to avoid performance degradation and to fully exploit the benefits of thermal storage in residential cooling. Full article

For automotive GFRP structural components, beyond structural design, the warpage, residual stress/strain, and fiber orientation inevitably induced during the injection molding process significantly compromise their service performance. These factors also diminish the reliability of performance assessments. Thus, it is imperative to develop a process–structure co-optimization approach for GFRP components. In this paper, the performance of a front-end module is evaluated through topological structure design, injection molding process optimization, and simulation with mapped injection molding history, followed by experimental validation and analysis. Under ±1000 N loading, the initial design shows excessive displacement at the latch mounting points (2.254 mm vs. <2.0 mm limit), which is reduced to 1.609 mm after topology optimization. By employing a sequential valve control system, the controls of the melt line and fiber orientation are is superior to thatose of conventional gating systems. The optimal process parameter combination is determined through orthogonal experiments, reducing the warpage to 1.498 mm with a 41.5% reduction compared to the average warpage of the orthogonal tests. The simulation results incorporating injection molding data mapping (fiber orientation, residual stress–strain) show closer agreement with experimental measurements. When the measured displacement exceeded 0.65 mm, the average relative error $E_r$, range $R$, and variance $s^2$ between the experimental results and mapped simulations were 11.78%, 14%, and 0.002462, respectively, validating the engineering applicability of this method. The methodology and workflow can provide methodological support for the design and performance assessment of GFRP automotive body structures, which enhances structural rigidity, improves control over injection molding process defects, and elevates the reliability of performance evaluation. Full article

The Qieliekeqi siderite deposit, located in the Tashkurgan block of western Kunlun, is a carbonate-hosted iron deposit with hydrothermal sedimentary features. This study integrates whole-rock geochemistry, stable isotopes, and zircon U–Pb–Hf data to investigate its metallogenic evolution. Coarse-grained siderite samples, formed in deeper water, exhibit average Al₂O₃/TiO₂ ratios of 29.14, δEu of 2.69, and δCe of 0.83, indicating hydrothermal fluid dominance with limited seawater mixing. Banded samples from shallower settings show an average Al₂O₃/TiO₂ of 17.07, δEu of 3.18, and δCe of 0.94, suggesting stronger seawater interaction under oxidizing conditions. Both types are enriched in Mn, Co, and Ba, with low Ti and Al contents. Stable isotope results (δ¹³C_PDB = −6.0‰ to −4.6‰; δ¹⁸O_SMOW = 16.0‰ to 16.9‰) point to seawater-dominated fluids with minor magmatic and meteoric contributions, formed under open-system conditions at avg. temperatures of 53 to 58 °C. Zircon U–Pb dating yields an age of 211.01 ± 0.82 Ma, with an average εHf(t) of −3.94, indicating derivation from the partially melted ancient crust. These results support a two-stage model involving Late Cambrian hydrothermal sedimentation and Late Triassic magmatic overprinting. Full article