Flexural Strength Research Articles

Characterizing eco-composite boards with non-woven polypropylene from disposable face masks and bamboo reinforcement

This study investigates the development of eco-composite panels using treated and untreated nonwoven polypropylene (PP) extracted from disposable medical face masks, reinforced with bamboo particles. Treated PP underwent a washing process with detergent. Panels were fabricated with varying PP-to-bamboo particle ratios of 100:0, 75:25, and 50:50. Fourier-transform infrared (FT-IR) spectroscopy analysis indicated minimal impact of washing on the intrinsic properties of the PP material, as confirmed by thermogravimetric analysis (TGA). Both analyses showed similar intensities of functional groups and thermal trends in treated and untreated recycled PP (rPP) samples. Energy-dispersive X-ray spectroscopy (EDX) confirmed the uniform integration of bamboo particles within the PP matrix by detecting silicon and potassium elements. Chemical interactions between bamboo fibres and the PP matrix were also evident in the form of reduced peak intensities in FT-IR spectra. Despite these interactions, limited adhesion between bamboo fibres and the PP matrix led to reduced stability and mechanical strength in the eco-composite panels. A direct correlation was observed between board thickness and the proportion of bamboo particles, with the 50:50 formulation showing the greatest thickness. Conversely, board strength decreased as bamboo particle concentration increased due to weak interfacial adhesion. Notably, panels made from treated rPP exhibited superior mechanical properties compared to those from untreated rPP, achieving a modulus of rupture (MOR) of 36.259 MPa and a modulus of elasticity (MOE) of 2048.215 MPa. These findings underscore the potential of utilizing nonwoven PP from disposable medical face masks, reinforced with bamboo fibre particles, to create eco-composite materials with enhanced sustainability and mechanical properties.

Mechanical properties of Al–Si alloy/Si3N4 interpenetrating phase composite based on a preform fabricated at 1200 °C

Interpenetrating phase composites with three-dimensional co-continuous architecture are promising materials for advanced structural applications due to their excellent combination of properties. In this work, a novel and low-cost Al–Si alloy/Si3N4 IPC was fabricated via squeeze infiltration of Al11Si alloy melt into a porous Si3N4 preform manufactured at a low temperature of 1200 °C using H3PO4 as pore-former and binder. Microstructures of IPC show a good infiltration quality and strong interfacial bonding between metal and ceramic phases without any intermediate reaction products. The fabricated IPC exhibited significantly higher specific hardness and stiffness than the Al11Si alloy. Moreover, an excellent damage tolerance, a substantial increase in compressive strength of 420 %, flexural strength of 168 %, and a significant reduction in wear rate of 95 % in the IPC was achieved with respect to Al11Si. The flexural strength and fracture toughness values of the fabricated IPC compare well to values of Al alloy/Si3N4 IPCs reported in the literature, despite being processed using a porous Si3N4 preform fabricated at a much lower temperature.

Low-toxic gelcasting of zircon ceramics

Zircon (ZrSiO4) ceramics are highly valued in various industries due to their exceptional physical and chemical properties. In the present work, zircon ceramics with high-density and desirable mechanical properties were successfully prepared using an aqueous gelcasting method, involving the use of a low-toxic and water-soluble monomer, N,N-dimethylacrylamide (DMAA), as the binder. A high solid loading and low viscosity zircon slurry was achieved by optimizing the pH and the dosage of the ammonium polyacrylate (PAA-NH3) dispersant. Zircon green bodies fabricated through the gelcasting method exhibited uniform microstructures and relatively high mechanical strength exceeding 11.0 MPa. The impact of solid loading on the density, decomposition, flexural strength, micro-hardness, and microstructure of the final ceramics were carefully studied. Notably, the ceramics, prepared by solidifying the slurry with a 45 vol.% solid loading and sintering the green body at 1550 °C for 2 h, exhibited a relative density of 96.3%, high phase purity, a uniform microstructure, and the highest flexural strength of 407.9 MPa. The results demonstrate that mechanically robust dense zircon ceramics can be effectively prepared using the low-toxic gelcasting method.

Cellulose nanofiber-induced metal–organic framework “armor” for the fabrication of carbon fibre composites with enhanced mechanical properties and electrical conductivity

Metal-organic frameworks (MOFs) possess significant potential in enhancing the interfacial performance of composites owing to their exceptional skeletal structures and substantial specific surface area. Herein, we prepared typical conductive MOFs (Ni-HHTP, HHTP = 2, 3, 6, 7, 10, 11-hexahydroxybenzene) at the interface by in situ synthesis using cellulose nanofibers (CNFs) assembled on the surface of carbon fibres (CFs) as precursors. CNFs can not only act as a smart cushion to promote stress release but also provide abundant oxygen-containing functional groups, such as hydroxyl and carboxyl groups, which can facilitate the growth of MOF on the surface of CFs. Furthermore, MOFs with porous structure and large specific surface area increase the interphase region for interfacial load transmission. The CF composites prepared using this strategy exhibited improvements in interlaminar shear strength (ILSS), interfacial shear strength (IFSS), flexural strength and flexural modulus by 57.9 %, 54.9 %, 35.1 % and 46.7 %, respectively. Additionally, the electrical conductivities of the composites in both thickness and in-plane directions were 1.04 × 10−4 S/cm and 7.3770 S/cm, respectively, which was attributed to the MOFs on the surface of the fibres facilitating the formation of good conductive channels between the fibres and resin. This study proposes an advanced interfacial modification approach to prepare CF composites with excellent mechanical and electrical conductivity properties.

A study of the efficacy and structural performance of modified coal tar and dimethylpolysiloxane as binders for coal-carbon composites

Amidst global resource depletion and population growth, repurposing carbon-containing waste as raw materials into products offers promise for a more resource-efficient, circular economy. This research examines the efficacy of using coal tar modified through air-blowing as a binder for producing coal composite, alongside exploring dimethylpolysiloxane as an alternative binder. The effects of the binder type, mixing ratios, and coal fine composition on the properties of the composites were systematically studied. Microscopic analysis revealed anisotropic spherules in pitch formed at 400 °C/9 h and 450 °C/6 h possess favorable chemical properties like low H/C ratios (0.24–0.25) and high carbon content (96–97 %). Pyrolyzed coal fines and modified pitch-based composites exhibited moderate weight loss (11–17 %), notable compressive strength (106.58–344.71 MPa), and flexural strength (49–160 MPa). However, composites produced from coal tar pitch (400 °C/9 h) blended with 50 % GG1 and further pyrolyzed at 600 °C for 5 h exhibited a high water absorption (19 %). Also, composites with inferior flexural strength were produced using dimethylpolysiloxane as a binder, rendering them unsuitable for structural applications. This straightforward approach offers a viable means to repurpose significant quantities of coal fines and coal tar destined for landfills. This research is intended as a reference for researchers seeking to tranform coal waste into structural composites, thereby promoting circularity, and mitigating associated environmental risks.

Thermal shock behavior of Al-Y2O3 doped aluminum nitride ceramics

Thermal shock resistance and mechanical reliability of aluminum nitride (AlN) ceramic substrates are essential in electronic device modules. In this study, the thermal shock behavior of AlN doped with aluminum - yttrium oxide (Al - Y2O3) was explored. The results indicate that adding Al to AlN ceramics increases its flexural strength, thermal conductivity, and thermal expansion coefficient. The microcracks caused by thermal mismatch between the AlN matrix and the secondary phases relieved internal stress, thereby improving thermal shock resistance of AlN ceramics. Furthermore, the addition of Al isolates and homogenizes the secondary phases, resulting in a more uniform microstructure and strengthened grain boundaries, which enhance the flexural strength, Weibull modulus, and thermal shock resistance. After introducing 0.5 wt% Al, the Weibull modulus of AlN ceramics increased by 73.37%, and their critical thermal shock temperature difference exceeded 800°C, with a maximum residual strength of 488.01 ± 48.26 MPa at 600°C. Overall, an appropriate amount of Al improves the reliability and thermal shock resistance of AlN ceramics.

Understanding the interface fracture mechanism by composite BFPMPC mortar and cement concrete bending beam

This study aims to utilize basalt fiber-reinforced polymer-modified magnesium phosphate cement (BFPMPC) mortar as an overlay for rapidly repairing surface defects such as raveling and delamination on Portland cement concrete (PCC) pavements, thereby swiftly restoring traffic flow and enhancing pavement service durability. Initially, double layered three-point bending fracture (DLTPB) tests were conducted on composite BFPMPC and PCC specimen with different predetermined crack lengths. The flexural strength was measured, fracture parameters were obtained based on the double-K fracture criterion, and crack propagation paths were determined using digital image correlation (DIC) methods. Subsequently, the fracture behavior of the composite beam was predicted by boundary effect model, and the interface microstructure between BFPMPC and PCC was characterized using nanoindentation, nano-scratch, and SEM/EDS techniques. Finally, by analyzing the fracture characteristics of the composite specimens, the crack propagation model was established and validated by finite element analysis (FEA). The results indicated that BFPMPC mortar overlay can enhance the flexural strength of composite structure. The unstable fracture toughness, cohesive fracture toughness, and fracture energy decreased with increase of crack length-to-height ratio (a0/D), while the initiation fracture toughness increased with increase of a0/D. DIC measurements provided insights into the morphology of the crack tip and the length of the fracture process zone (FPZ). The boundary effect model predictions aligned with the fracture characteristics of the specimens, which were controlled by nonlinear fracture criteria. Nanoindentation tests revealed that the mechanical properties of the interface are influenced by multiple sub-interfaces, with the elastic modulus relationship being ITZ-4 > ITZ-2 > ITZ-3 > ITZ-1. Further analysis of scratch hardness and scratch fracture toughness confirmed that the BFPMPC-PCC interface exhibited high fracture toughness, which was crucial for improving structural resistance to fracture. SEM/EDS observations revealed significant cracks at the interface between BFPMPC and ordinary Portland cement (OPC), while cracks between BFPMPC and coarse aggregates were smaller. Subsequently, the fracture analysis model for composite specimens was proposed to finely reveal interface fracture failure, and the FEA results exhibited a high degree of consistency with experimental results.

Development and Optimization of Machine Learning Models for Estimation of Mechanical Properties of Linear Low-Density Polyethylene

A hybrid methodology was developed and implemented for estimation of polymeric mechanical properties in rotational moulding process. The considered polymer in this study is linear low-density polyethylene, known as LLDPE, which has extensive application in plastic industry. The mechanical properties of the polymer were assessed and correlated to the oven residence time to build the predictive model of moulding process. A tiny dataset containing only 25 data rows via a number of machine learning models were assessed. Oven residence time is the only input, while the LLDPE’s properties including tensile strength, impact strength, and flexure strength are the outputs considered in the machine learning models. We used tree-based ensemble methods for modeling in this work and they are tuned using FA (Firefly Algorithm) optimizer to find optimal hyper-parameters of them. Finally, the optimal models had shown a great performance to predict the output accurately. For tensile strength, the best model (FA-ET) has an R2 value of 0.9994, this score is 0.9995 for impact strength and 0.9968 for flexure strength. The tree-based models tuned in this study revealed to be robust in estimation of polymeric properties and can be used to obtain the products with the best quality.

Self-sensing ultra-lightweight engineered cementitious composites (ECC) with carbon fibres

This research introduces self-sensing ultra-lightweight engineered cementitious composites (ULW-ECCs) by hybridizing polyethylene fibre and carbon fibres (CF) designed for structural health monitoring and retrofitting applications. The investigation explores the self-sensing performance and electrical conductivity of smart ULW-ECC with seven CF lengths ranging from 1 to 20 mm. Initially, mechanical properties and electrical conductivity were assessed, followed by the impact of temperature and water content in composite on electrical conductivity. The self-sensing capability under both tension and flexure was examined, complemented by a scanning electron microscope (SEM) test. The density of smart ULW-ECC fell within the range of 1000–1200 kg/m3 under the compressive strength of about 30 MPa. The integration of CF enhanced the compressive and flexural strength while reducing the tensile strain capacity. The electrical conductivity of the specimen with CF initially raised and then slightly declined with CF length from 1 to 20 mm, with the highest conductivity observed at 12 mm. Incorporating CF could diminish the influence of the environment on the electrical conductivity of ULW-ECC. Furthermore, the inclusion of CF improved the self-sensing performance of ULW-ECC, especially during the tensile strain-hardening (multiple microcracking) stage, although this efficacy was subject to variation based on CF length. Considering the mechanical, self-sensing, and conductive properties, it is recommended to utilize CF lengths within the range of 9–12 mm. This work confirms that CF-reinforced ULW-ECC could achieve excellent mechanical properties and self-sensing ability.

Effects of external staining on mechanical, optical, and biocompatibility properties of additively manufactured 3Y-TZP ceramic for dental applications

Three mole percent yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramics are exemplary materials for dental restoration due to their high mechanical strength, fracture toughness, chemical endurance, and biocompatibility. Nevertheless, 3Y-TZP ceramics are opaque and their CAD/CAM manufacturing process may cause micro-cracks in conventional clinical practice. In this study, 3Y-TZP ceramic samples were prepared using vat photopolymerization, pre-sintering, external staining, and final high-temperature sintering. The microstructures, mechanical properties, optical properties, and cytotoxicity of the 3Y-TZP ceramic samples were investigated. The results indicate that with increasing Fe3+ concentration of staining solution from 0.1 mol/L to 0.3 mol/L and increasing staining time from 5 s to 30 min, the 3Y-TZP ceramic samples showed a tetragonal crystal structure of zirconia with densely packed grains and a slight increase in grain size. The flexural strength, Vickers hardness, and fracture toughness of 3Y-TZP ceramic samples stained in 0.1–0.3 mol/L Fe3+ solution for 5 s to 3 min were all greater than 665 MPa, 11.9 GPa, and 5 MPa·m1/2, respectively, meeting the mechanical requirements for clinical application. Colorimetric analysis revealed a decrease in L* (black-white index) from 90.4 to 81.3, an increase in a* (green-red index) from −1.5 to 3.2, and an increase in b* (blue-yellow index) from 11.6 to 20.3, approximating the commercial VITA 3D-Master Shade Guide chromaticity. Furthermore, the 3Y-TZP ceramic samples exhibited a cell viability of 90% or higher toward L929 cells.

Comparative analysis of the technological properties of natural and agglomerated stones in epoxy matrix

Brazil occupies a prominent position among the countries that produce the most ornamental stones in the world, with emphasis on the state of Espírito Santo. However, despite this success in production, the sector faces a considerable challenge in relation to waste generation. The objective of this study was to produce and evaluate the technological properties of an agglomerated stone using 87 wt% waste from the processing of Branco Fortaleza stone in a matrix with 13 wt% epoxy resin, using the vacuum vibro-thermo-compression process. The waste was characterized by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The stones were subjected to evaluation of density, apparent porosity, water absorption, abrasion resistance test, staining, chemical attack, 3-point flexural strength and microstructural analysis (SEM). The results showed a density of 2.26 ± 0.02 g/cm3, water absorption of 0.24 ± 0.01%, apparent porosity of 0.55 ± 0.03%, abrasion resistance test of 1.38 mm and flexural strength of 30.13 ± 1.74 MPa. The results compared with the literature reveal a material with technical feasibility to be used as a coating in the construction sector, presenting high mechanical resistance, good interfacial adhesion, application on high traffic floors, as well as environments subject to liquid penetration such as sinks, floors and countertops. Using this waste to manufacturing new materials, such as agglomerated stones, can not only help reduce dependence on raw materials, but also play an important role in minimizing the environmental impact associated with the extraction and processing of natural stones.

Compositional effects of Si–Mg–Al composite fillers on the interfacial microstructure and high-temperature strength of SiC/SiC brazed joints

This study proposes the use of Al-added Si–Mg composite fillers for low-temperature joining of SiC while maintaining high-temperature reliability of the joints. SiC was brazed at 1100 °C using the fillers with various compositions, based on Mg-evaporation-induced isothermal solidification of Si. The interfacial microstructure and mechanical properties of the joint were determined for different Al and Mg compositions in the filler. The added Al promoted Mg evaporation during joining, which increased the joint strength by mitigating the brittleness of the Si-based bonding layers. However, metallic Al remained in the bonding layers, which deteriorated the high-temperature joint strength. Higher Mg and Al concentrations in the filler promoted MgAl2O4 formation in the bonding layers that correlated with Al particle refinement. This contributed to an improvement of the joint properties, with the flexural strength at 1200 °C in air exceeding 60 MPa.

Mechanical evaluation of DIW-printed carbon nanofibers - Alumina-Toughened Zirconia composites

Direct ink writing (DIW) offers cost-effective fabrication of intricate ceramic structures. However, the mechanical properties (reliability) of DIW-obtained components have been inadequate for structural applications. This study aimed to improve mechanical properties of DIW alumina-toughened zirconia (ATZ) composite filaments with and without carbon nanofibers (CNFs). Optimized debinding and sintering conditions were determined for Conventional Sintering (CS) and Spark Plasma Sintering (SPS). The influence of nozzle diameter, CNF content and sintering method on the fracture strain, Young’s modulus, flexural strength and Weibull modulus was carefully assessed via correlation analyses. CNFs, although intended to enhance properties, were often agglomerated, which negatively affected mechanical properties. Smaller nozzle diameters enhanced Young’s modulus, with CS-sintered ATZ filaments showing transformation-induced plasticity (TRIP). Mechanical properties rivaled or surpassed those of conventional techniques (e.g., cold isostatic pressing, slip casting) with a good level of mechanical reliability achieved. Overall, DIW showed promise for ceramic materials, particularly ductile Ce-TZP-based composites.

Performance of Fly ash/GGBFS based geopolymer concrete with recycled fine and coarse aggregates at hot and ambient curing

The incorporation of recycled aggregates in geopolymer concrete (GPC) exhibits higher environmental sustainability due to its ability to utilize industrial by-products and construction and demolition (C&D) waste. This study investigates the combined effect of fine and coarse recycled aggregates on the behavior of GPC. In this research, fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binder, whereas sodium silicate (Na2SiO3)and sodium hydroxide (NaOH) were used as alkaline activators. Recycled fine aggregates (RFA) were used at 30%, 60% and 100% replacement of natural fine aggregates (NFA) and recycled coarse aggregates (RCA) were used at0%,50% and 100% replacement of natural coarse aggregates (NCA). To study the effect of curing temperature, two types of curing regimes, i.e. hot and ambient curing, were employed. Performance of developed GPC was evaluated in terms of workability, mechanical properties (compressive strength, splitting tensile strength, and flexural strength) and durability properties such as water absorption, sorptivity, resistance against acid attack, resistance against marine environment and electrical resistivity. It was found that the behavior of GPC is improved when the samples were cured at high temperature for 24 hours, as compared to the samples cured under ambient curing conditions. Furthermore, NFA can be replaced up to 100% with NCA, and up to60%in the presence of 50% RCA and up to 30% in the presence of 100% RCA. It was also found that with an increase in the percentage of recycled aggregates, durability performance gradually declined. The results showed that GPC can be developed with inclusion of both recycled fine and coarse aggregates, which can help to preserve valuable natural resources, reduce CO2emission, and dispose C&D waste.

Prediction of flexural strength in FRP bar reinforced concrete beams through a machine learning approach

PurposeThe purpose of this study is to assess the incorporation of fiber reinforced polymer (FRP) bars in concrete as a reinforcement enhances the corrosion resistance in a concrete structure. However, FRP bars are not practically used due to a lack of standard codes. Various codes, including ACI-440-17 and CSA S806-12, have been established to provide guidelines for the incorporation of FRP bars in concrete as reinforcement. The application of these codes may result in over-reinforcement. Therefore, this research presents the use of a machine learning approach to predict the accurate flexural strength of the FRP beams with the use of 408 experimental results.Design/methodology/approachIn this research, the input parameters are the width of the beam, effective depth of the beam, concrete compressive strength, FRP bar elastic modulus and FRP bar tensile strength. Three machine learning algorithms, namely, gene expression programming, multi-expression programming and artificial neural networks, are developed. The accuracy of the developed models was judged by R2, root means squared and mean absolute error. Finally, the study conducts prismatic analysis by considering different parameters. including depth and percentage of bottom reinforcement.FindingsThe artificial neural networks model result is the most accurate prediction (99%), with the lowest root mean squared error (2.66) and lowest mean absolute error (1.38). In addition, the result of SHapley Additive exPlanation analysis depicts that the effective depth and percentage of bottom reinforcement are the most influential parameters of FRP bars reinforced concrete beam. Therefore, the findings recommend that special attention should be given to the effective depth and percentage of bottom reinforcement.Originality/valuePrevious studies revealed that the flexural strength of concrete beams reinforced with FRP bars is significantly influenced by factors such as beam width, effective depth, concrete compressive strength, FRP bars’ elastic modulus and FRP bar tensile strength. Therefore, a substantial database comprising 408 experimental results considered for these parameters was compiled, and a simple and reliable model was proposed. The model developed in this research was compared with traditional codes, and it can be noted that the model developed in this study is much more accurate than the traditional codes.

Poly(butylene succinate) reinforced by small amount of grafted nanofibrillated bacterial cellulose: Toughness variability based on nanocomposites preparation method

Polybutylene succinate (PBS) is a promising biodegradable polymer; however, its low mechanical performance limits its application. To address this issue, long fiber length nanofibrillated bacterial cellulose (HP-NFBC), produced by a bottom-up process using cellulose-producing bacterium and hydroxypropyl cellulose (HPC) as a dispersing agent was used as reinforcement agent. Hydrophobic moieties were grafted on HP-NFBC surface to increase surface compatibility. Nanocomposites prepared by both solvent casting and melt-kneading were evaluated. By solvent casting, the addition of 0.25 wt% of grafted HP-NFBC increased the toughness by 212%. Melt-kneading revealed an increase in flexural strength and young’s modulus. More evident improvement was observed when the nanocomposites were annealed, and the ultimate strength increased by 113 % at 2 wt% of grafted HP-NFBC incorporation. Great increased in toughness were achieved only by small incorporation of grafted HP-NFBC. Additionally, compost biodegradation tests were conducted to confirm that the nanocomposites had biodegradability similar to that of PBS.

Testing and Evaluation of Hybrid Polymer Composites Reinforced with Moringa oleifera and Boehmeria nivea Fibers, Embedded with Copper Oxide Particulates, for Thermal, Structural, and Biological Properties

Abstract The increasing need for sustainable materials in industrial applications has prompted a significant shift in attention from synthetic to natural fibers. This study examines the problems and opportunities arising from the utilization of natural fiber-reinforced polymer composites in several industrial sectors. The objective of this work is to fabricate a hybrid composite using a conventional hand layup technique with natural reinforcement of Moringa oleifera (MO) and ramie (Boehmeria nivea) fibers, an epoxy matrix blended with copper oxide filler, utilized to enhance material stability and antimicrobial activity. To quantify the effect of five different weight fractions of MO and ramie fibers on this hybrid composite, its mechanical, thermal, functional, and antifungal properties were examined. The superior tensile strength (61.34 MPa), flexural strength (64.78 MPa), and impact energy (23 J) results indicate that ramie fiber loading should be increased. Additionally, enhanced thermal properties such as thermal conductivity (0.93 W/mK), heat deflection temperature (97°C), thermal expansion coefficient (1.7210−5/°C), and maximal thermal stability were observed at 347°C as a result of the increased ramie fiber loading. This analysis demonstrates that this hybrid composite possesses the antifungal activity necessary to form an inhibition zone against Candida albicans. Scanning electron microscopy analysis was conducted to determine the hybrid composites’ bonding strength and failure mode.

Dispersion Strategy improves the mechanical properties of 3D-Printed biopolymer nanocomposite

Homogenous dispersion of nanoparticles in polymer matrices is a technical challenge that if overcome can lead to improved mechanical properties of the resulting nanocomposites. In this work, we successfully refined commercially-available nanoscale, calcium deficient, and poorly crystalline hydroxyapatite (nHA) particles and composited them with acrylate and methacrylate functionalized soybean oil (mAESO) and triethylene glycol dimethacrylate (TEGDMA) producing inks for masked stereolithography (mSLA) -based 3D printing. First, we used shear mixing and ultrasonication on nHA/ethanol mixtures to break down agglomerates and then separated the finest nanoparticles from the remaining agglomerates using centrifugation. The refined nanoparticles (termed fine) were then mixed with the resins and UV-initiator to produce inks for 3D printing. Similarly, we prepared one ink using as-purchased nHA particles (termed raw) and another ink using leftover agglomerates after refinement (termed coarse). We compared the rheological properties of the nHA-resin inks. We used mSLA to fabricate nanocomposite specimens and tested them using flexural, and Mode-I fracture toughness testing following ASTM standards. The dispersion of nanoparticles in the polymer matrix was studied by analyzing backscattered mode scanning electron microscopy images. The nHA particle refinement improved the nanoparticle dispersion in the resin matrix while also increasing the viscosity and shear yield strength of the nanocomposite ink. The flexural fracture strength, flexural modulus, and Mode-I fracture toughness of refined nHA-based nanocomposites were increased by 11 %, 71 %, and 12 %, respectively compared to the raw nHA-based nanocomposites. However, the flexural fracture strain of refined nHA-based nanocomposites was lower by 40 % compared to the raw nHA-based nanocomposites. The nanocomposites became stiffer with the incorporation of refined nanoscale nHA. The separation of nanoscale nHA particles, excellent dispersion of these nanoparticles in polymer matrix, and improved flexural strength and modulus opens a new avenue towards the 3D printing of high-performance nHA-based nanocomposites.

Effect of mullite fiber on the properties of glass composite sealing materials

Glass-based sealing materials exhibit significant potential for utilization in solid oxide fuel cells (SOFCs). We conducted a study on the impact of mullite fibers with varying particle sizes on glass composite sealing materials. We evaluated and discussed properties such as coefficient of thermal expansion (CTE), softening temperature (Ts), gastightness, interfacial compatibility, and flexural strength of the sealing materials with different ranges of fiber particle sizes. Our findings indicate that the three different particle sizes of mullite fiber-glass composite sealing materials met the required coefficients of thermal expansion, displayed good interfacial compatibility, and exhibited gastightness lower than 0.0016 sccm cm−1. Notably, the mullite fiber-reinforced sealing material that underwent ball-milling for 1 h outperformed the other two variants. It demonstrated fewer defects, a 57.1 % increase in flexural strength, and a 117.4 % higher maximum strain value.

Improvement of the mechanical properties of the cement mortar by the incorporation of silica particles with low and high surface area

In recent years, nanoaprticules with different sizes have been incorporated in the cement mortar in order to improve their mechanical characteristics. The present work focuses onto the influence of the silica nanoparticles (SiO2) with low and high surface area over the stability and mechanical properties of the cement mortar. The quantities of nanosilica added into the cement mortar to ameliorate their mechanical characteristics vary from 0.5 % to 1.5 %wt. The obtained material after the incorporation of the SiO2 nanoparticles have been characterized by several techniques such as TG, DTG, DSC and their morphologies were determined by using SEM analysis. The workability, water absorption, compressive and flexural strengths of these materials have also been evaluated. The results obtained show that the introduction of the SiO2 nanoparticles into the cement mortar has been greatly improved their compressive and flexural strengths, and the specimens incorporated by nanosilica with high surface area are found more effective than those containing the silica nanoparticles with low surface area, suggesting that the specific surface play a crucial role in the improvement of their mechanical properties. The results show also that the appropriate dosage of silica nanoparticles in the cement mortar to have a maximum enhancement of their mechanical properties was found around 1.5 wt% by weight of cement for the nanosilica with high surface area.