Pure Glass Research Articles

No-Core optical fibers sensor for detecting hemoglobin concentration (HB) based on the Surface Plasmon resonance.

In this work, a fiber-optic biomedical sensor was manufactured to detect hemoglobin percentages in the blood. SPR-based coreless optical fibers were developed and implemented using single and multiple optical fibers. It was also used to calculate refractive indices and concentrations of hemoglobin in blood samples. An optical fiber, with a thickness of 40 nanometers, was deposited on gold metal for the sensing area to increase the sensitivity of the sensor. The optical fiber used in this work has a diameter of 125μm, no core, and is made up of a pure silica glass rod and an acrylate coating. The length of the fiber was 4cm removed buffer and the splicing process was done. It is found in practice that when the sensitive refractive index increases, the resonant wavelength increases due to the decrease in energy.

Study on the Inter-Laminar Shear Strength and Contact Angle of Glass Fiber/ABS and Glass Fiber/Carbon Fiber/ABS Hybrid Composites

In recent days, the uses of 3D printing have been successfully implemented in various applications due to their advantages. Besides, the need for sustainable choice has created a demand for the augmented use of thermoplastic composites. Thus, additive manufacturing techniques have become the essence of composite fabrication to achieve an automated and flexible fabrication technique. The present study used fused deposition modelling (FDM) and hot press moulding technique to produce composite samples. The composite laminates were fabricated by using acrylonitrile butadiene styrene (ABS) as polymer and woven glass fiber (GF) and woven carbon fiber (CF) used as reinforcements. Further, the laminates were subjected to inter-laminar shear strength (ILSS) and contact angle. The inter-laminar shear strength and the contact angle of hybrid samples were compared with virgin ABS and pure glass fiber-reinforced composites. The study reported a maximum ILSS of 198.5MPa achieved by GF/CF/ABS hybrid composites, which was higher by 17% and 217% compared with GF/ABS and ABS samples, respectively. The contact angle results showed an increase due to the incorporation of fibers with ABS by 5% and 13% in GF/ABS and GF/CF/ABS, respectively, contributing to the adhesion. The contact angle values achieved were 100.5°, 105.15°, and 113.39° by ABS, GF/ABS and GF/CF/ABS making them hydrophobic in nature. These developed reinforced materials, such as carbon fiber, glass fiber and ABS matrix composites, could be used in automotive, aerospace and wind energy applications.

Carbon Enrichment in the Lithospheric Mantle: Evidence from the Melt Inclusions in Mantle Xenoliths from the Hainan Basalts

AbstractIt is generally believed that the lithospheric mantle and the mantle transition zone are important carbon reservoirs. However, the location of carbon storage in Earth's interior and the reasons for carbon enrichment remain unclear. In this study, we report CO2‐rich olivine‐hosted melt inclusions in the mantle xenoliths of late Cenozoic basalts from the Penglai area, Hainan Province, which may shed some light on the carbon enrichment process in the lithospheric mantle. We also present a detailed petrological and geochemical investigation of the late Cenozoic basalts and mantle xenoliths from northern Hainan Island. The collected samples of late Cenozoic Hainan Island basalts belong to both alkaline and subalkaline series, showing fractionated REE patterns with high (La/Yb)Nvalues of 3.52–11.77, which are typical for OIB. Based on Al‐in‐olivine thermometry, the temperatures estimated for the mantle xenoliths can be divided into two groups. One group has temperatures of less than 1050°C, and the other group has temperature ranging from 1050°C to 1282°C. Clinopyroxene (La/Yb)N–Ti/Eu and clinopyroxene Ca/Al–Mg#diagrams indicate that the mantle peridotite experienced metasomatism from both silicate and carbonate melts. Melt inclusions in the olivine of mantle xenoliths include (1) CO2bubble–rich melt inclusions; (2) multiphase melt inclusions (glass + CO2bubble + daughter minerals); (3) pure glass melt inclusions. Magnesite is a daughter mineral in the olivine‐hosted melt inclusions, which could be interpreted as a secondary mineral formed by the interactions of CO2‐rich fluids with an olivine host, due to post‐entrapment effects. The glasses in olivine‐hosted melt inclusions have high SiO2contents (60.21–77.72 wt%). Our results suggest that a considerable amount of CO2‐rich melt inclusions are captured in the lithospheric mantle during metasomatism. The lithospheric mantle can therefore act as is a ‘carbon trap’, with much CO2being absorbed by the lithospheric mantle in this way.

Modeling thermophysical properties of glasses

Metal oxide glasses are important in various industries because their properties can be tailored to meet application-specific requirements. However, there are few rigorous modeling tools for predicting thermomechanical properties of these materials with acceptable accuracy and speed, yet these properties can play a critical role in material design. In this article, a general multi-scale modeling framework based on Monte Carlo simulation and a cubic equation of state for predicting thermomechanical properties is presented. There are two novel and fundamental aspects of this work: (1) characterization of glass transition and softening temperatures as adjacent saddle points on the heat capacity versus temperature curve, and (2) a new moving boundary equation of state that accounts for structure and ‘soft’ repulsion. In addition, modeling capabilities are demonstrated by comparing thermomechanical properties of a pure B2O3 glass and PbO–B2O3 glass predicted by the equation of state to experimental data. Finally, this work provides a rigorous approach to estimating thermophysical properties for the purpose of guiding experimental work directed at tailoring thermomechanical properties of glasses to fit applications.

Viscosity of crystal-free silicate melts from the active submarine volcanic chain of Mayotte

Following an unprecedented seismic activity that started in May 2018, a new volcanic edifice, now called Fani Maoré, was constructed on the ocean floor 50 km east of the island of Mayotte (Indian Ocean). This volcano is the latest addition to a volcanic chain characterized by an alkaline basanite-to-phonolite magmatic differentiation trend. Here, we performed viscosity measurements on five silicate melts representative of the East-Mayotte Volcanic Chain compositional trend: two basanites from Fani Maoré, one tephriphonolite and two phonolites from different parts of the volcanic chain. A concentric cylinder viscometer was employed at super-liquidus conditions between 1500 K and 1855 K and a creep apparatus was used for measuring the viscosity of the undercooled melts close to the glass transition temperature in the air. At super-liquidus temperatures, basanites have the lowest viscosity (0.11–0.34 to 0.99–1.16 log10 Pa⸱s), phonolites the highest (1.75–1.91 to 3.10–3.89 log10 Pa⸱s), while the viscosity of the tephriphonolite falls in between (0.89–1.97 log10 Pa⸱s). Near the glass transition, viscosity measurements were performed for one phonolite melt because obtaining pure glass samples for the basanite and tephriphonolite compositions was unsuccessful. This is due to the formation of nanolites upon quench as evidenced by Raman spectroscopy. The phonolite viscosity ranges from of 10.19 log10 Pa⸱s at 1058 K to 12.30 log10 Pa⸱s at 986 K. Comparison with existing empirical models reveals an underestimation of 1.2 to 2.0 log units at super-liquidus and undercooled temperatures, respectively, for the phonolite. This emphasizes (i) the lack of data falling along the alkaline basanite-to-phonolite magmatic differentiation trend to calibrate empirical models, and (ii) the complexity of modeling viscosity variations as a function of temperature and chemical composition for alkaline compositions. The new measurements indicate that, at eruptive temperatures between 1050 °C and 1150 °C (1323–1423 K), the oxidized, anhydrous, crystal-free and bubble-free basanite melt have a viscosity around 2.6 log10 Pa⸱s. In contrast, the anhydrous phonolite crystal- and bubble-free melt would have a viscosity around 6–10 log10 Pa⸱s at expected eruptive temperatures, from 800 to 1000 °C (1073–1273 K). Considering that both basanite and phonolite lavas from the Mayotte submarine volcanic chain contain <6% crystals and a significant amount of water (1-2.3 wt% and 0.8-1.2 wt%, respectively), such viscosity values are probably upper limits. The new viscosity measurements are essential to define eruptive models and to better understand the storage and transport dynamics of Comoros Archipelago magmas, and of alkaline magmas in general, from the source to the surface.

Investigation of gallium and tin on IG5 commercial chalcogenide glass and glass ceramics

In this research, optical, mechanical, and thermal properties of chalcogenide glasses in a Se-Ge-Sb system were studied with 1, 3, 5, 7, and 9 % Gallium and tin. Glass samples melted at 850 °C for 20 h were quenched in the melted salt. XRD analyses were performed for them. The properties of this ternary system compared in presence of two different additive. The aim of this study was to improve the mechanical properties of the Se60Sb12Ge28 chalcogenide glass (IG5) with the thermal treatment and prepare glass ceramics with high strength and IR transmittance. The glasses exhibited about 70 % IR-transmission around 2–17 µm with the weakest peaks. The hardness of these pure glasses increased by adding the Gallium and improvement of the melting conditions and quenching so that it reached ∼ 230–345 Kg.mm2. This high hardness was firstly reported for chalcogenide glasses. Appropriate temperature and time were selected to precipitate sub-micron nanocrystals and prepare ceramic glasses, heat treatment was also performed. The size and distribution of nanocrystals in the glass ceramic microstructure was investigated by Fe-SEM and TEM. The hardness of this ceramic glass reached to ∼ 280–370 MPa by precipitation of nanocrystals with diameter of 100–400 nm.

Acetylated tunicate nanocellulose-based high-efficient air filter media with antibacterial property

Nanocellulose has great potential for application in highly efficient filter media. However, its application is hindered significantly by the structure collapse of nanofiber networks due to capillary adhesion and hydrogen bonds formed during the wet-laid process. Here, the tunicate nanocelluloses (TNCs) are modified with acetic anhydride and (3-Aminopropyl) triethoxysilane, respectively, to alleviate such collapse of the nanofiber networks. The obtained acetylated tunicate nanocelluloses (ANCs) and silylated tunicate nanocelluloses (SNCs) are applied to fabricate composite filter media together with a glass fiber (GF) substrate layer. The filtration efficiency of TNC/GF, ANC/GF, and SNC/GF filter media increase to 99.983%, 99.991%, and 99.994%, respectively, compared with pure glass fibers filter media (99.916%). The smaller air resistance of ANC/GF filter media (314.3 Pa) compared to that of TNC/GF (323.9 Pa) and SNC/GF (346.7 Pa) filter media contributes to a larger quality factor (0.03 Pa-1). The ANC/GF filter media shows antibacterial capability. The survival rate of escherichia coli (E. coli) and staphylococcus aureus (S. aureus) bacteria with an original concentration of 2✕107 cell/mL decreased to 44.2% and 5.8%, respectively, after exposure to ANC/GF filter media for 6 h. Their survival rate decreased to less than 0.5% after exposure to the ANC/GF filter media loaded with silver nanoparticles for 1 h. This work will promote the application of nanocellulose in highly efficient air filter media.

Structural, optical behavior and Judd-Ofelt analysis of europium-doped silicophosphate glasses for red-emitting device applications

Silicophosphate glasses doped with europium are of great interest in fundamental fields such as photonics, luminous diodes, optoelectronics, and lasers. In the present study, we have focused on exploring the effect of the europium (Eu3+) dopant on the structural, physical, and optical properties of silicophosphate glasses. In this study, pure and europium-doped silicophosphate glasses were synthesized by using the sol-gel method. To evaluate the structural and optical properties of the prepared glasses, X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible spectroscopy, photoluminescence spectra, and luminescence decay of trivalent europium ions in glasses were examined. XRD revealed that all of the synthesized glasses contained amorphous phases. FTIR transmittance spectra demonstrated that the addition of europium in the silicophosphate glass leads to a reduction in the dimensionality of the network as a result of the rupture of the Si–O–Si bonds into their structure. The band gap energy of the samples increases with the dopant of europium. The photoluminescence spectrum shows the line characteristics of the Eu (III) ion 5D0→7FJ (J = 0, 1, 2, 3 and 4). Large bands were observed, suggesting non-homogeneous sites that are characteristics of amorphous systems. The intensity parameters ΩJ (J = 2, 4) and the radiative properties of Eu3+ ions in the prepared glasses, such as the stimulated emission cross-section (σe), transition probability (A), radiative lifetime (τcal), and branching ratio (βR) were determined, and Eu3+ emission may be suggested for suitable laser applications due to its high value of βR=52.71%. Furthermore, the CIE 1931 color coordinates of the synthesized glass (x, y) are within the range of (0.63, 0.36) and are quite close to the standard red color (0.67, 0.33), indicating that pure bright red emission has been achieved. The obtained results show that the europium-doped silicophosphate glasses can be appropriate for use as a red laser material.

Properties of flame-retardant leaf fiber cement-based composites at high temperatures

Flame retardant modification of leaf fibers was carried out to solve the technical problem of poor fire resistance of plant fibers and improve the utilization rate of urban fallen leaves in building materials. The modification scheme adopts three flame retardants, i.e., ammonium polyphosphate (APP), magnesium hydroxide (MH), and aluminum hydroxide (ATH), and two covering layers, i.e., pure acrylic polymer lotion and water glass (Na2O · nSiO2) solution. The modified leaf fiber's combustion behavior and pyrolysis properties were tested and analyzed. The physical and mechanical characteristics, as well as the thermal insulation qualities, of leaf fiber cement-based composites (LFCC) were studied at high temperatures. The findings revealed that the three flame retardants had an effect on the chemical structure of leaf fibers. In comparison to leaf fibers without flame-retardant modification, flame-retardant-modified leaf fibers have a much greater thermal stability. and its LOI is greater than 27.0%, which is a fire-retardant material. Except for the sample with water glass as the modified cover layer, at high temperatures, the composite flame-retardant fiber LFCC's mass-loss rate is lower compared with fibers without flame-retardant modification or fibers modified with only one kind of flame-retardant. In the composite flame-retardant modified fiber LFCC, the samples with better strength at high temperature are those with ATH replacing 30% and 50% MH. The thermal conductivity of LFCC is negatively correlated with the range of temperature change.

Novel transition metal modified layered phosphate for reducing the fire hazards of PA6

To date polyamide 6 (PA6) have been widely applied in many different fields such as mechanical parts, electronic and electrical products. Nevertheless, the inherent flammability of PA6 threaten the safety of life and properties, restricting its comprehensive applications. In this work, three types of metal phosphate modified layered melamine phytate hybrids are designed and prepared by supramolecular self-assembly technology, and the hybrids are incorporated into glass fiber reinforced PA6. The flame retardancy as well as smoke suppression properties of the composites with different transition metal modified flame retardants are compared and investigated. The results of cone calorimeter test indicate that the metal phosphate modified layered melamine phytate based composites can reduce both the peak heat release (pHRR, <32%) and total heat release (THR, <28%) compared to those of pure glass fiber reinforced PA6; the smoke and toxic volatiles productions are also reduced significantly, and Cu phosphate modified layered melamine phytate hybrids (PA-MEL-Cu) perform better than other flame retardants on suppressing the heat release and smoke releasing of PA6. The mechanism investigations demonstrate that the improved fire safety properties of PA6 composites are attributed to the physical barrier effect and the selective catalysis effect of transition metal during the combustion. This strategy not only prepares metal phosphate modified layered melamine phosphate by in-situ precipitation, but also promotes the promising potentials of melamine phosphate in the flame retardant application of polymer composites.

Castor Oil-Based Polyurethane/S2 Glass/Aramid Hybrid Composites Manufactured by Vacuum Infusion.

This study evaluates the hybridization effect of S2-glass/aramid on polyurethane (PU) composites produced by vacuum infusion. Different laminates were produced with similar thickness (around 2.5 mm), using, as reinforcement, only aramid fabrics (five layers, named as K5) or only S2-glass fabrics (eight layers, named as G8). Furthermore, hybridization was obtained by manufacturing symmetrical hybrid inter-ply laminates, with four S2-glass layers and two of aramid, (G2K)S and (KG2)S. The mechanical response of the laminates was evaluated in tensile, interlaminar shear strength, dynamical mechanical analysis and quasi-static indentation tests, and related to their morphological characteristics. The main results show that the pure glass composites presented less voids, but a higher density as well as higher tensile stiffness and strength. The aramid laminates showed a high capability for absorbing impact energy (ca. 30% higher than the pure glass laminates), and the hybrid laminates had intermediate properties. More importantly, this work shows the possibility of using a polyurethane matrix for vacuum infusion processing, effective even for aramid/S2-glass hybrid composites with thermoset polyurethane resin. This study is therefore promising for impact absorption in applications such as protective armor. The studied hybrid laminate may display a suitable set of properties and greater energy absorption capability and penetration resistance for impact applications.

Enhanced mechanical and electrical properties of ECR-glass reinforced polyimide composites with incorporation of TiO2 for insulation applications

This paper presents the mechanical behaviour of novel class composites consisting of ECR-glass type reinforced polyimide (PI) composite loaded with TiO2 nanoparticles. ECR glass reinforced PI composites were fabricated by adding TiO2 particles at three different concentrations namely; 2, 4, and 6 wt% using 3D-Turbula dispersion and Spark Plasma Sintering (SPS) method. The morphologies, crystallinity, mechanical, and electrical properties of the produced composites were evaluated using scanning electron microscope (SEM), X-ray diffractometer, nanoindentation test, and LCR meter device. The SEM results revealed that the TiO2 nanoparticles were homogenously dispersed into the PI composites. The mechanical properties, such as hardness, stiffness, and elastic modulus of the pure PI and ECR glass reinforced PI composite was improved by the incorporation of TiO2 nanoparticles. Maximum hardness and elastic modulus values of 2.19 GPa and 13.99 GP, respectively, was observed in ECR reinforced PI composited loaded with 6 wt% TiO2 nanoparticles. In addition, ECR glass reinforced PI composites with 6 wt% TiO2 nanoparticles depicted the lowest dielectric constant (1.18), dielectric loss (1.14) and electrical conductivity (3.16 × 10−6 S/cm). Finally, the findings suggest the easy processability of PI nanocomposites and their potential for mechanical and electrical insulation applications.

Experimental Investigation on the Mechanical and Physical Properties of Glass/Jute Hybrid Laminates.

Natural fibres have been partly substituting synthetic fibres in polymer composites due to their renewable character and many other advantages, and sometimes, they can be hybridized into a single composite for a better combination of properties. This work aims to study the effect of hybridization and stacking sequence on the mechanical and physical properties of the glass/jute laminates. For that, pure jute, pure glass and glass/jute hybrids were manufactured by vacuum infusion process using orthophthalic polyester resin. The composites were characterized via C-scan analysis, density, volume fraction of constituents and optical microscopy analyses. Mechanical properties were obtained from tensile, compression and shear tests. The longitudinal properties were higher than transverse properties for all laminates. The hybrids presented intermediate density and mechanical properties compared to pure glass and pure jute laminates. The hybrids produced similar density and tensile modulus, but with small differences in tensile strength and compressive strength which were justified based on variations in resin and void content due to the influence of the stacking sequence (glass/jute interlayer regions). In addition, the pure glass and the hybrid laminates displayed acceptable failure morphology in the in-plane shear test, but not the pure jute laminate.

NaPON Doping of Na4P2S7 Glass and Its Effects on the Structure and Properties of Mixed Oxy-Sulfide-Nitride Phosphate Glass.

The preparation, properties, and short-range order (SRO) structures of glasses in the series (1-x)[2/3Na2S + 1/3P2S5] + x[1/3Na2S + 2/3NaPO2.31N0.46] = Na4P2S7-6xO4.62xN0.92x, where 0 ≤ x ≤ 0.5 (NaPSON), are reported on. In this study, these mixed oxy-sulfide-nitride (MOSN) glasses were prepared by adding the nitrided material NaPO3-(3/2)yNy; y = 0.46 = NaPO2.31N0.46 (NaPON) to the base sulfide glass Na4P2S7. For comparison purposes, additions of the unitrided material, y = 0, NaPO3, were also studied (NaPSO). Accordingly, large batches of bubble-free glass could be prepared making this route of nitrogen doping amendable toward scaling-up the glass melting process; though, only small amounts of nitrogen could be incorporated in this manner. Nitrogen and sulfur compositional analysis were combined with XPS, Raman, FT-IR, and 31P MAS NMR spectroscopies to determine the amount of retained nitrogen in the glass after melting and quenching and to determine the effect of the added nitrogen and oxygen on the structure of the base pure sulfide glass Na4P2S7, x = 0.0. The nitrogen content increased linearly with the addition of NaPON, but was found, through quantitative 31P MAS NMR analysis, to be approximately half that expected at each value of x. Despite the small amount of nitrogen retained in these glasses, profound increases in the glass transition (Tg) and crystallization temperatures (Tc) were found with increasing x. For the intermediate values of x, 0.2 and 0.3, no crystallization of the supercooled melt was observed even 250 °C above the Tg. It was found that the addition of NaPON to the series caused a disproportionation reaction, where the oxide and oxy-nitride SRO species preferentially formed covalent, networking phosphate chains, forcing the sodium modifier to ionic sulfide units with large fractions of nonbridging sulfurs (NBSs). This disproportionation reaction was also observed in the NaPO3 doped series of glasses, but to a smaller extent. Oxygen was found in both bridging oxygen (BO) and nonbridging oxygen (NBOs) structures while the sulfur was predominantly found in nonbridging sulfur (NBS) structures. N 1s XPS and 31P NMR studies provided insight into the nitrogen bearing phosphorus units and the wt % of nitrogen that was retained in the quenched glasses. It was found that trigonally coordinated nitrogen (Nt) was preferentially retained in the melt, whereas it is proposed that the linearly coordinated (doubly bonded) nitrogen (Nd) accounts for the lost nitrogen in the glasses.

Experimental Study on the Impact of Clay Distribution and Mineralogy on NMR T2 and Internal Gradient: Insights From Well-Controlled Physical Samples

Summary Nuclear magnetic resonance (NMR) is a reliable tool for petrophysical evaluation and the characterization of pore structures. Compared to conventional carbonate reservoirs, sandstone reservoirs contain higher amounts of ferromagnetic and paramagnetic ions (such as iron, nickel, or manganese) usually found in microporous clay aggregates. The interpretation of petrophysical data in sandstone formations can be complicated by variations in clay mineralogy and distribution patterns (laminated, structural, and dispersed). Nevertheless, the impact of clay distribution patterns on NMR signals is not well understood. This study aims to investigate the impact of clay mineralogy and distribution patterns on the T2 relaxation times and internal gradient (i.e., inhomogeneity in the magnetic field). Glass beads were mixed with three different clay minerals characterized by no iron content (kaolinite) to higher iron content (illite and nontronite). The bead-clay mixtures were prepared at a fixed clay content but with variable clay distribution patterns to examine the impact of clay distribution alone. NMR T2 measurements at several echo times were performed on the pure glass beads and the mixtures to evaluate how clay mineralogy and distribution patterns affect the T2 and the internal gradient of the host glass beads. At a given clay distribution pattern, a more significant decrease in T2 relaxation times and a larger increase in the internal gradient of glass beads were observed when adding clays with higher iron content. This is explained by the higher surface relaxivity, and magnetic susceptibility caused when introducing clay with higher iron content. Such an impact can complicate the characterization of NMR-derived pore sizes as similar pore size distribution (PSD) can have very different T2 distribution and the logarithmic mean of T2 relaxation time distribution (T2LM) values. Micro-computed tomography (µCT) images were acquired to compute the PSD to compare it with ones obtained from the NMR measurements. The PSD for the three clay minerals showed almost the same distribution using µCT; however, they showed totally different T2 relaxation times distributions. That is due to the significant impact of the internal gradient causing a distortion in the magnetic field. Thus, careful consideration must be taken before converting the NMR data into PSD. The introduction of iron-free kaolinite resulted in a negligible impact on the internal gradient of glass beads regardless of the clay distribution pattern. On the other hand, the addition of dispersed iron-rich clays (illite and nontronite) results in up to two orders of magnitude increase in internal gradients, compared to mixtures with laminated and structural clays (at the same clay mineralogy and content). Moreover, dispersed clay mixtures display larger changes in T2LM and porosity as a function of increasing echo time. The results from this study suggest that changes in T2LM and the logarithmic mean of the effective internal gradient distribution geff,LM, compared to the clean host sand, can provide insight into iron-rich clay distribution. Larger changes in any given clay content and mineralogy would suggest a more dominant dispersed clay distribution while negligible changes would suggest a laminated distribution.

Hydroxylation and water-surface interaction for S-glass and silica glass using ReaxFF based molecular dynamics simulations

Hydrolysis at the water-glass interface significantly influences glass surface reactivity and adhesion characteristics. In glass fiber reinforced epoxy composite interphases, hydroxyls on the glass fiber surface reacts with silane coupling agents to form covalent bonds between the fiber and polymer matrix. In this study, the surface reactivity and hydrolysis reaction of silica glass and S-glass (Mg aluminosilicate glass with 65 % SiO2, 25 % Al2O3, and 10 % MgO in weight ratio) are simulated using ReaxFF molecular dynamics (MD) to investigate the formation of surface defects (i.e., under-coordinated atoms) and hydroxyls (number density, types and spatial distribution) at four surface annealing temperature conditions (300 K, 700 K, 1000 K and 1300 K). Our study showed that a higher areal number density of surface defects and hydroxyls formation occur at lower surface annealing temperature conditions. S-glass was predicted to have a lower number density of hydroxyls compared to pure silica glass. In addition, analysis on hydroxyl oxygen revealed the defects and oxide bond connected to Mg are responsible for hydrolysis in S-glass. RDF and hydroxyl categorization analysis revealed the S-glass could have closer proximity among hydroxyls despite the lower hydroxyl areal number density than silica glass. Lastly, silica glass showed more physisorbed water and surface energy, which agrees with previous studies. This surface hydrolysis and reactivity analysis study will guide the experiments to control the fiber coating process to tailor interphase in glass fiber-epoxy composites.

Encapsulation of nano-Si into MOF glass to enhance lithium-ion battery anode performances

Although metal-organic framework (MOF) glasses have exhibited high potential to be applied as anode materials for lithium-ion batteries (LIBs), their electrochemical performances still need to be greatly improved to match the rapid development of green energy technologies. Silicon is a promising candidate for the next generation of LIB anode but suffers from vast volume fluctuations upon lithiation/delithiation. Here, we present a strategy to in situ grow a kind of MOF, namely, cobalt-ZIF-62 (Co(imidazole)1.75(benzimidazole)0.25) on the surface of Si nano particles, and then to transform the thus-derived material into Si@ZIF-glass composite (SiZGC) through melt-quenching. The robust hierarchical structure of the SiZGC based anode exhibits the specific capacity of ∼650 mA h g-1, which is about three times that of pure ZIF glass and about six times that of pristine ZIF crystal at 1 A g-1 after 500 cycles. The origin of this huge enhancement is revealed by performing structural analyses. The ZIF glass phase can not only contribute to lithium storage, but also buffer the volume changes and prevent the aggregation of Si nano particles during lithiation/delithiation processes.

Evaluation of tensile properties on glass/carbon fiber epoxy pure, interply, and locally nested intraply hybrid composites

AbstractIn this study, the behavior of pure glass fiber/epoxy, pure carbon fiber/epoxy, interply hybrid, and locally nested intraply hybrid composites under tensile load was investigated. The specimens were produced by the vacuum‐assisted resin transfer molding (VARTM) method. Interply hybrid composites showed approximately the average tensile strength of the glass and carbon fiber/epoxy composites, with 603 MPa. Intraply hybrid composites had 17% lower tensile strength than pure glass fiber/epoxy composites due to the discontinuity of the fibers in the structure. Therefore, pure or interply hybrid composites are suitable in cases where tensile strength is more important, while in special cases where different properties are desired in different regions of a monolithic structure, locally nested intraply hybrid composites can be used. While the finite element analysis (FEA) results of pure and interply hybrid composites were very close to the tensile test, the amount of deviation increased in intraply hybrid composites due to fiber discontinuity. Fiber and void volume fractions of hybrid specimens were found to be around 62% and 1.45%, respectively. The numerical and experimental results of pure carbon fiber/epoxy composite are validated by the analytical solution.

Thermal, Microstructural and Electrochemical Hydriding Performance of a Mg65Ni20Cu5Y10 Metallic Glass Catalyzed by CNT and Processed by High-Pressure Torsion

A Mg65Ni20Cu5Y10 metallic glass was produced by melt spinning and was mixed with a 5 wt.% multiwall carbon nanotube additive in a high-energy ball mill. Subsequently, the composite mixture was exposed to high-pressure torsion deformation with different torsion numbers. Complimentary XRD and DSC experiments confirmed the exceptional structural and thermal stability of the amorphous phase against severe plastic deformation. Combined high-resolution transmission electron microscopy observations and fast Fourier transform analysis revealed deformation-induced Mg2Ni nanocrystals, together with the structural and morphological stability of the nanotubes. The electrochemical hydrogen discharge capacity of the severely deformed pure metallic glass was substantially lower than that of samples with the nanotube additive for several cycles. It was also established that the most deformed sample containing nanotubes exhibited a drastic breakdown in the electrochemical capacity after eight cycles.

Thermal Regeneration and Reuse of Carbon and Glass Fibers from Waste Composites

This article aims to develop a method for regenerating and reusing carbon and glass fibers extracted from unrecyclable scraps of carbon plastics, printer parts, and laminating coating. A comparison of known methods of fiber regeneration revealed the advantages of thermal treatment: absence of costs of reagents and complex equipment; better preservation of composition; and strength of fibers. Based on the results of thermographic analysis of wastes in nitrogen and air, the destruction temperatures of their organic matrices were determined (200-460°С), and the use of calcination instead of pyrolysis was justified. The appearance and surface quality of the regenerated fibers are characterized by optical and electron microscopy. It has been established that quantitative extraction of pure carbon and glass fibers from waste crushed to 1 cm is efficient by their calcination at 700 °C for 0.5 h and 500 °C for 1 h, respectively. The principle of creating new composites with the obtained fibers based on the similarity of their composition and binding materials (matrices) has been proposed. It was shown that the introduction of 1 wt% of fibers into slag blocks and active carbon pellets considerably increases their compressive strength, but the bending strength does not change due to dispersed reinforcement. Possible improvement of mechanical properties of products requires reagent treatment of the fiber surface or the introduction of binder additives. Calculations show that the developed method of recycling composite waste can produce 2.3 tons/hour of reinforced building materials that are good for the environment and the economy, excluding expenses for landfill waste disposal and reducing the cost of the product by replacing the primary fiber for the secondary one. Doi: 10.28991/ESJ-2022-06-05-04 Full Text: PDF