Higher Flexural Strength Research Articles

Synthesis and properties of low viscosity robust biobased benzoxazine resin

The preparation of biobased benzoxazine resin with low melting point and low curing temperature has important significance for environmental sustainable development and practical application in industrial field. In this paper, biobased benzoxazine monomer HA-fa was synthesized from p-hydroxybenzyl alcohol, paraformaldehyde and furfurylamine, and H-fa were prepared by Mannich reaction of hordenine with paraformaldehyde and furfurylamine. The two benzoxazine organic molecules showed different thermodynamic behaviors. HA-fa and H-fa were liquid at room temperature. The viscosity of HA-fa and H-fa at room temperature (25 °C) were 1.683 Pa/s and 0.602 Pa/s, and the curing peak temperature was 220 °C and 208 °C, respectively, both organic molecules showed excellent processability. Then poly(HA-fa) and poly(H-fa) were prepared by two organic molecules through thermal curing procedure. The comprehensive properties of two benzoxazine resins were investigated. The glass transition temperature (Tg) of poly(H-fa) is 223 °C, while the Tg of poly(HA-fa) has two peak temperatures, 225 °C and 281 °C, respectively. This may be due to the existence of two different crosslinking networks in the resin, which leads to the phase separation of the resin, thus reflecting two Tg. Meanwhile, the initial thermal decomposition temperatures Tdi of poly(HA-fa) and poly(H-fa) were 330 °C and 331 °C, respectively, showing excellent thermal stability of the newly prepared resin. In addition, poly(HA-fa) and poly(H-fa) have both high storage modulus (3174 MPa and 2608 MPa, respectively, measured at 25 °C) and good flexural strength (121 ± 2.7 MPa and 96 ± 3.6 MPa). Among the two resins, poly(HA-fa) showed more excellent comprehensive properties, which may be based on the joint action of resin multi-crosslinking sites and hydrogen bond crosslinking network.

Chemical‐treated sisal fiber reinforcement in red mud composites: Advancing mechanical strength and environmental sustainability

AbstractThe use of industrial waste red mud in polymer composites promotes environmental sustainability by mitigating the environmental impacts associated with landfill disposal. Previous research by the authors on red mud sisal fiber composites resulted in increased strength; it is expected that the strength can be increased further through fiber treatment. As a result, the current study sought to examine the effects of chemical‐treated sisal fiber reinforcement on the mechanical properties of red mud composites. Alkaline treatment and silane treatment were both used as chemical treatment methods. Red mud was added in three different weight percentages, and composites were built using the compression molding method and tested for hardness, tensile strength, flexural strength, and impact strength. The findings indicate that the strength of the composite increases with the incorporation of treated fibers, silane‐treated 30% red mud composites showed a maximum hardness of around 92 shore D. The tensile strength of the composites containing 20% red mud and treated with silane was the highest, reaching ca. 63 MPa. This significant increase in strength was attributed to the formation of strong interfacial bonding between the red mud, fiber, and matrix. Furthermore, the silane‐treated 20 wt% red mud composites have the highest flexural strength (ca. 244 MPa) and impact strength (ca. 26 J/m). However, increasing the red mud content above 20 wt% resulted in decreased tensile, flexural, and impact strength due to poor bond development, and red mud agglomeration. The findings of this study are beneficial for the design and development of composites based on red mud, as well as for promoting sustainable waste management practices.Highlights Red mud composites achieve superior mechanical strength. Chemical treatment enhances sisal fiber reinforcement. Sustainable waste management promoted through composite utilization. Strong interfacial bonding improves composite performance.

Preparation and characterization of snake plant fiber reinforced composite: A sustainable utilization of biowaste

AbstractNatural fibers are one of the most attractive materials in biocomposites due to their potential for sustainability. This study aims to prepare sustainable composite materials using fibers from Sansevieria trifasciata (snake plant) and to investigate their mechanical, morphological, and water absorption properties. The composite was prepared with epoxy resin through a manual hand lay‐up process, maintaining standard parameters with changeable reinforcement (10%, 20%, and 30%). The mechanical properties (tensile, impact, and flexural strength), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and water absorbency of the composites were evaluated. The result showed that the tensile strength, flexural strength, and impact resistance of the composites are 6.99 MPa, 10.77 MPa, and 14 J, respectively, for 30% fiber components, which are significantly higher than other composite materials. The SEM analysis showed a strong interfacial bond between the snake plant fiber and the epoxy resin. The FTIR analysis revealed a reduction in hemicellulose and lignin and an improvement in the interfacial adhesion between snake plant fiber and epoxy resin. The composites also demonstrated time‐dependent increases in water absorption, with the sample containing 30% fiber components showing the best absorbency performance at 0.88%.Highlights A study is being conducted on the effective and sustainable use of biowaste. The composite materials loaded with 30% fibers had significantly high tensile strength, flexural strength, and impact resistance. The SEM analysis of snake plant fiber‐reinforced polymer composite showed a strong interfacial bond between fiber and epoxy resin. The FTIR analysis of the composite revealed the reduction of hemicellulose and lignin. The use of non‐renewable materials is reduced, and eco‐friendliness is promoted.

Bridging graphene sheets to ultra-high-performance graphene-based bulk materials via Si-C bonding and Y-type carbon structure

Graphene is the strongest material ever identified. However, the fabrication of graphene-based bulk materials from graphene powders presents a significant challenge. Here, a new strategy to fabricate high performance graphene based bulk materials by introducing silicon nanoparticle is proposed. Consequently, ultra-high compressive strength and high flexural strength are achieved, measuring as high as 1102 MPa and 455 MPa, respectively. The compressive strength at the microscale even reaches a remarkable 5.17 GPa. The superior strength of the bulk material is primarily attributed to the Y-type carbon structure and Si-C bonds. The Y-type carbon structures in graphene, produced by the self-propagating high-temperature synthesis (SHS) method, and the Si-C covalent bonds formed at the interface between graphene and SiC contribute to a tight linkage of graphene sheets, thereby preventing slippage of graphene sheets. In addition, the microstructure evolution process of Si-SHS-graphene bulk material is clarified. With the introduction of silicon nanoparticles, the oxidation resistance of graphene based bulk materials is substantially improved, the weight loss is around 6% after oxidized at 1000 °C. This study carries extensive implications for understanding the impact of Y-type carbon structures and the effect of Si-C bonds in graphene-based bulk materials.

Multiscale Engineered Waste Wood Particles toward a Sustainable, Scalable, and High‐Performance Structural Material

AbstractDeveloping sustainable and lightweight structural materials is a promising strategy for reducing carbon emissions in transportation and buildings. However, producing high‐performance bulk structural materials from sustainable biomass materials while maintaining excellent mechanical strength remains a major challenge, especially for further scale‐up. Herein, a scalable and robust bottom‐up strategy is reported to fabricate bulk wooden plate (W‐plate) with a typical “brick‐and‐mortar” structure from engineered wood particles via moderate delignification and in situ LiCl/DMAc treatment followed by hot‐pressing. The W‐plate constructed by delignified wood particles and regenerated cellulose nanofibers can achieve a confluence of mechanical strengthening and toughening by the ordered lamination structure and multiscale cellulose micro/nanofiber crosslinking interactions, resulting in high flexural strength (225.17 ± 12.18 MPa) and high fracture toughness (4.01 ± 0.53 MPa m0.5) while maintaining a low density (1.34 g cm−3), superior to typical metals and ceramics. Moreover, the W‐plate exhibits advantageous thermal properties, including a low thermal expansion coefficient (<19 × 10−6 K−1) and a high storage modulus (>7.5 GPa) compared to those of petroleum‐based polymers. Coupled with abundant and renewable raw materials, all‐cellulose components, and scalable and recyclable fabrication, the W‐plate can potentially be used as a high‐performance, cost‐effective, and environmentally friendly alternative for engineering applications.

Effect of SPS frequency on the transformation of diamond to graphite in WC-Co composite

(WC–6wt%Co)/5Vol% diamond composites were successfully fabricated at 1150–1300 °C and 40 MPa for 5 minutes under the thermodynamically unstable conditions of the Spark Plasma Sintering method. The influence of on-off time, and frequency of the DC pulse of SPS on diamond stability, microstructure, and mechanical properties of WC–Co/diamond composites were investigated. The diamond particles are strongly bounded with the cemented carbide matrix by a transition layer composed of a solid solution of tungsten and carbon in cobalt. The amount of graphitization was low in the sintered composites at 1300 °C due to the low temperature and short sintering time. Reduction of SPS frequency effectively inhibited graphite preformation, and no graphite was detected in the sintered composites at 1150 °C. Diamond morphology was not affected during SPS as examined by SEM, and Raman scattering spectra. The uniform dispersion of the super-hard diamond phase in matrix which good bonded, caused the high hardness, fracture toughness and flexural strength of this composite. The reduction of pulse frequency of SPS leads to a significant enhancement in the hardness, fracture toughness, and flexural strength of the composites, overcoming the graphitization of diamond typically observed in SPS. The sample sintered with 4 Hz showed simultaneously the highest hardness (23.6 GPa), the highest fracture toughness (24.6 MPa.m½), and the highest flexural strength (2050 MPa).

Low‐velocity impact response and post‐impact assessment of self‐healing composites with different stacking configurations of core–shell nanofibers

AbstractThis work investigates the low‐velocity impact (LVI) and self‐healing behavior of carbon fiber composite laminates interlaced with electrospun polyacrylonitrile core–shell nanofibers (PAN@CFRP). The main goal is to investigate the influence of different stacking configurations of core–shell nanofibers on the impact resistance and self‐healing properties of composite laminates. To achieve the purpose, three different stacking configurations were designed and tested alongside virgin specimens. The damage mechanism and self‐healing of laminates following LVI were determined using ultrasonic C‐scan and cross‐sectional microscopy examinations. At an impact energy of 14.1 J, the flexural strength of the post‐healing PAN‐3@CFRP specimen reached 95.0% of the initial value, whereas at an impact energy of 21.8 J, severe impact damage was observed in the laminates with different configurations. Among the laminates, the PAN‐1@CFRP specimen had the highest flexural strength after healing, which reached 80.1% of its pre‐impact strength. As observed, the impact resistance and self‐healing capacity of composites could be significantly enhanced by optimizing the distribution configuration of core–shell nanofibers for various impact energies.Highlights The introduction of electrospun core–shell nanofibers has not significantly compromised the mechanical properties of the composites, but rather enhanced their toughness. The addition of core–shell nanofibers significantly enhances the impact resistance of the composites and imparts excellent self‐healing properties to the material. The flexural strength of impact‐damaged specimens with different stacking configurations can be restored up to 95% of the undamaged specimen after repair treatment. Significantly improved impact resistance and self‐healing ability of laminates by optimizing the distribution configuration of core–shell nanofibers between composite layers.

High-strength, high-porosity and low-shrinkage Al2O3 ceramics prepared by flexible adjustment of CaCO3 size and content

A high-strength, high-porosity and low-shrinkage Al2O3 ceramics was prepared by direct ink writing method (DIW) using CaCO3 as a mineralizer. The effect of CaCO3 size and content on the phase formation, microstructural evolution and properties of porous Al2O3 ceramics sintered at 1400 ℃ were systematically investigated. The results showed that the properties of the porous Al2O3 ceramics were significantly affected by the particle size and content of CaCO3. The fine particle size and increased CaCO3 content could enhance the effective contact area between CaCO3 and Al2O3, facilitating the reaction at high temperatures during the sintering at 1400 ℃. It was found that the favorite sintering condition promoted the formation of calcium hexaluminate (CA6) and calcium dialuminate (CA2). Microstructure analysis revealed that CA6 exhibited a lamellar and tabular morphology, concentrated primarily at the pore boundaries, while some CA6 were adhered on the surface of Al2O3 particles. CA2 were mainly embedded around Al2O3 particles. The increase of CA6 and CA2 contents improved the flexural strength and porosity, and decreased the shrinkage rate. The Al2O3 ceramics with high flexural strength, high porosity and low shrinkage rate were successfully fabricated by adding 20 wt% CaCO3 with the particle size D90 below 7.8 µm. The resulting flexural strength and porosity were 8.9 MPa and 71.9%, respectively, representing an improvement of 21.9% and 19.8% compared to Al2O3 ceramics without CaCO3. Additionally, the shrinkage rate in the X (0.9%), Y (1.1%), and Z (1.5%) directions decreased significantly, and the corresponding reductions were 75.0%, 73.2%, and 74.1%, respectively.

Slurry infiltration and sintering cycle‐dependent mechanical properties of 3D oxide/oxide ceramic matrix composites

AbstractIn this study, oxide/oxide ceramic matrix composites reinforced with three‐dimensional fiber preform were fabricated by a slurry infiltration and sintering (SIS) process. The influence of the SIS cycle on microstructures and mechanical properties of the 3D oxide/oxide composite was investigated. Results showed that the porous matrix was densified due to the SIS effect. The elastic modulus of the weak matrix and interfacial shear strength increased with the increasing SIS cycle. This led to an obvious improvement in flexural strength and interlaminar shear strength of the composite. The fracture toughness and work of fracture of the composite slightly decreased. A good balance between fracture strength and damage tolerance was achieved on the sixth SIS fabricated oxide/oxide composite, which had a high flexural strength of 295.1 ± 14.9 MPa, a high interlaminar shear strength of 18.2 ± .5 MPa, and a high fracture 11.5 ± .8 MPa m1/2. The SIS process is a promising way to fabricate the 3D oxide/oxide composite.

Characterization of tannin extracted from Aningeria altissima bark and formulation of bioresins for the manufacture of Triumfetta cordifolia needle-punched nonwovens fiberboards: Novel green composite panels for sustainability

The new Aningeria altissima tannins extracted from ground bark were characterized by ATR-FT MIR and MALDI-ToF spectrometry. The tannin extracts were found to contain flavonoids and glucose, with a strong predominance of chalcone and gallocatechingallate monomers typical of condensed tannin proanthocyanidins. Two different formulations of resins bio-cured with hexamine and exudates from the Vachellia nilotica tree were analyzed (gel time, TMA and ATG) and used to manufacture biocomposite panels of carded-needled non-woven fibers of Triumfetta cordifolia (TC) natural fibers. The new biocomposites bonded with extracted Aningeria altissima tannin showed high water sensitivity, exceeding EN 622–5. The incorporation of TC fibers increased the thermal degradation temperature of biocomposites and improved their thermal stability. The mechanical properties of both biocomposites are high in the weft direction, which is favored by the preferential orientation of the fibers in this direction. In particular, the high flexural strength and flexural modulus are good enough to meet the specifications of current international standards for fiberboards used in dry conditions. The biocomposite with the optimum properties was obtained from fibers bonded with hexamine-cured tannin resin.

Structure and Mechanical Properties of Milled and 3D-Printed Ti-6Al-4V Alloys for Subtractive and Additive CAD/CAM Manufacturing in Dentistry

The mechanical properties, structure, and morphology of milled and 3D-printed Ti-6Al-4V alloys produced by selective laser melting were investigated in this study. The mechanical properties were investigated by means of nanoindentation, a tensile test, and a three-point bending test. An Atomic Force Microscope (AFM) was used to study the surface topography and roughness of both titanium alloys. The surface structure and phase analyses were studied by a scanning electron microscope (SEM) and through powder X-ray diffraction (XRD). The results from the nanoindentation experiments showed that the 3D-printed sample has higher indentation hardness and modulus than the milled one. The AFM observation of the surface topography of the samples showed that the milled sample has a higher roughness than the 3D-printed one. The tensile test results showed that the 3D-printed sample by means of Selective Laser Melting (SLM) technology has about 26% higher tensile strength and smaller elongation than the milled one. The three-point bending test revealed that the 3D-printed Ti-6Al-4V sample has higher flexural strength than the milled one. It was found that the 3D-printed sample has a smaller crystal size than the milled one, which, according to the Hall–Petch relationship, leads to its higher indentation hardness.

Effects of Physical and Mechanical Properties of Coir Fiber and Reinforced Epoxy Composites Treated with Acetic Anhydride and Alkali

ABSTRACT Modified coir fiber improves compatibility between fiber and matrix. To explore a better fiber treatment approach and enhance the mechanical properties of composites, this study conducted alkali treatment and acetic anhydride treatment on long and short coir fibers. The effects of different treatments on the properties of coir fibers were characterized using TGA, FTIR, SEM, and stereomicroscopy, and the mechanical properties of the composites were tested. Results showed that the tensile strength of alkali-treated coir fibers (ACF) and acetic anhydride-treated coir fibers (AACF) were remarkably improved. Notably, ACF exhibited a significant 69% increase in tensile strength. The tensile strength of composites with alkali-treated long coir fibers (ALC) and composites with alkali-treated short coir fibers (ASC) reached 34.51 and 21.14 MPa, respectively. The highest flexural strength was found for the acetic anhydride-treated coir fibers, and the flexural strength of composites with acetic anhydride-treated long coir fibers (AALC) and composites with acetic anhydride-treated short coir fibers (AASC) reached 54.38 and 53.46 MPa, respectively. This study presents an improved methodology for enhancing the interfacial bonding ability between coir fibers and the matrix, consequently improving the properties of composites. It offers reference for the investigation of natural fiber composites.

Analysis of Topography, Flexural Strength, and Microstructure of a Lithium Disilicate Glass- Ceramic after Surface Finishing.

To investigate the influence of finishing, polishing, and glazing on the roughness, flexural strength, and microstructure of lithium disilicate glass-ceramics. LD CAD/CAM blocks were cut into 96 discs (1.2 × 12 mm). After crystallization, a layer of glaze was applied to the discs' surfaces. The specimens were randomly divided into eight groupsn = 12) for different surface treatments (glaze [G], diamond abrasion [D], find diamond abrasion [F], and polishing [P]): G(glaze, control), GD, GDG, GDP, GF GFG, GFP, and GDFP. Mean roughness (Ra), mean square height (Rq), and maximum roughness (Rz) were measured. The biaxial flexural strength test was performed in a universal testing machine at 0.5 mm/minute. Microstructural analysis was performed using x-ray diffraction patterns (XRD). Differences on the roughness obtained in distinct groups was analyzed with Kruskal-Wallis and Bonferroni tests (α = .05). The flexural strength tests were compared with one-way ANOVA. Glazed groups (G, GDG, and GFG) presented the lowest surface roughness, lower crystallinity, and higher flexural strength than the other groups. Although polishing and glaze presented similar surface roughness, polishing protocol decreased the flexural strength compared to the control group G. Clinically adjusted LD glass-ceramic restorations should be reglazed whenever possible to improve strength.

Densification and microstructural correlation with thermo-mechanical strength of TiO2-doped (Al1-xCrx)2O3 (x=0.1, 0.3) solid solution ceramics

In this work, TiO2-doped (Al1-xCrx)2O3 (x = 0.1, 0.3) ceramics were prepared in the range of 1600 °C–1700 °C under a slightly reducing atmosphere. The lattice parameter calculations only showed a minor increment with TiO2 doping, implying a meager solid-solubility limit (also detected by EDS semi-quantification). The grain size of (Al1-xCrx)2O3 is directly proportional to the TiO2 amount and sintering temperature. Beyond the TiO2 solid solubility limit, exaggerated grain growth and excessive pore formation were observed at higher sintering temperatures. The highest flexural strengths were observed without TiO2 at a higher sintering temperature and with 1 wt% TiO2 at lower sintering temperatures. However, higher TiO2 inclusion has deleterious effects on flexural strengths, as the failure occurs via a combined effect of porosity and larger grains.

Effect of surface topography and wettability on shear bond strength of Y-TZP ceramic

Zirconia ceramics have been widely used as dental restorations due to their esthetic appearance and high flexural strength. The bonding of zirconia with resin cement should rely on both mechanical and chemical bonds. This study was performed to investigate the effect of zirconia surface topography and its wettability after surface pretreatments on the microshear bond strength (μSBS) of a resin cement. Zirconia slabs were prepared and randomly divided into 5 groups based on the surface treatment as follows: no treatment (control), air abrasion (AB), etching with hydrofluoric acid (F), the mixture of hydrofluoric acid and nitric acid (FN), or the mixture of hydrochloric acid and nitric acid (CN) for 10 min. The specimens were subjected to investigation of surface roughness characteristics [average roughness (Ra), peak-to-valley average distance (Rpv), skewness (Rsk), and kurtosis (Rku)] using atomic force microscopy (AFM) and measurements of surface contact angle (θc) and μSBS of a resin cement. In addition, the area % of the nanoscale surface irregularity (nSI%) was calculated from the AFM images. The effects of nSI%, Ra and θc on the μSBS were analyzed by multiple linear regression analysis (p < 0.05). Multiple regression analysis revealed that the nSI% was the most predominant factor for the μSBS (p < 0.001). A surface with larger nSI%, higher Ra and relatively lower θc was essential for establishing a reliable resin-zirconia bond.

Effect of diamond volume fraction on the microstructure and mechanical properties of SPS WC–Co/diamond composites

AbstractIn this research, the effect of the volume percentage of diamond additive on the sintering behavior, microstructure, and mechanical properties of WC–Co was investigated. WC–Co/diamond composites with different percentages of 0%, 2.5%, 5%, 7.5%, and 10% by volume of diamond were made by spark plasma sintering at 1300°C and 40 MPa for 5 min. A small amount of phase transformation from the diamond phase to the graphite phase was observed. The amount of graphitization was low due to low temperature and short sintering time. The addition of diamond leads to a significant enhancement in both the hardness and fracture toughness of the composites, overcoming the trade‐off between hardness and toughness typically observed in WC‐based materials. The sample reinforced with 5% by volume of diamond showed simultaneously the highest hardness (22.9 GPa), the highest fracture toughness (22.7 MPa m1/2), and the highest flexural strength (1896 MPa). The uniform dispersion, good bonding of the superhard diamond phase with the matrix, and the fine microstructure caused the high hardness and toughness of composite. The main effective mechanisms in increasing the fracture toughness of the composite were crack deflection, bridging, and blocking of crack propagation by diamond particles.

Effects of boron source on properties of pressureless solid-state sintered silicon carbide ceramics

The effects of the boron source (B, BN, and B4C) on the thermal, electrical, and mechanical properties of pressureless solid-state sintered SiC ceramics were investigated. A high relative density of 99.9 % was successfully achieved for all ceramic specimens using an appropriate additive composition and ideal sintering conditions. SiC ceramics sintered with B and B4C additives displayed higher electrical and thermal conductivities and higher flexural strength than those sintered with the BN additive at the same relative density. The presence of intrinsically-weak, electrically-insulating BN grains at the junction and grain boundaries increased both the fracture toughness and electrical resistivity, while the flexural strength and thermal conductivity of the ceramics decreased. The electrical resistivity, thermal conductivity, and flexural strength of the SiC ceramics were able to be adjusted with values ranging from 3.2 × 104–1.6 × 106 Ω‧cm, 72.4–147.5 W‧m−1‧K−1, and 386–545 MPa, respectively, depending on the boron source used.

Boron-containing coating yields enhanced antimicrobial and mechanical effects on translucent zirconia

ObjectivesTo evaluate the mechanical and antimicrobial properties of boron-containing coating on translucent zirconia (5Y-PSZ). Methods5Y-PSZ discs (Control) were coated with a glaze (Glaze), silver- (AgCoat), or boron-containing (BCoat) glasses. The coatings' antimicrobial potential was characterized using S. mutans biofilms after 48 h via viable colony-forming units (CFU), metabolic activity (CV) assays, and quantification of extracellular polysaccharide matrix (EPS). Biofilm architectures were imaged under scanning electron and confocal laser scanning microscopies (SEM and CLSM). The cytocompatibility was determined at 24 h via WST-1 and LIVE&DEAD assays using periodontal ligament stem cells (PDLSCs). The coatings' effects on properties were characterized by Vickers hardness, biaxial bending tests, and fractography analysis. Statistical analyses were performed via one-way ANOVA, Tukey's tests, Weibull analysis, and Pearson's correlation analysis. ResultsBCoat significantly decreased biofilm formation, having the lowest CFU and metabolic activity compared with the other groups. BCoat and AgCoat presented the lowest EPS, followed by Glaze and Control. SEM and CLSM images revealed that the biofilms on BCoat were thin and sparse, with lower biovolume. In contrast, the other groups yielded robust biofilms with higher biovolume. The cytocompatibility was similar in all groups. BCoat, AgCoat, and Glaze also presented similar hardness and were significantly lower than Control. BCoat had the highest flexural strength, characteristic strength and Weibull parameters (σF: 625 MPa; σ0: 620 MPa; m = 11.5), followed by AgCoat (σF: 464 MPa; σ0: 478 MPa; m = 5.3). SignificanceBCoat is a cytocompatible coating with promising antimicrobial properties that can improve the mechanical properties and reliability of 5Y-PSZ.

ENHANCING THE DURABILITY PROPERTIES OF CEMENT STONE THROUGH THE INCORPORATION OF BASALT FIBER REINFORCEMENT

The primary focus in designing a cement slurry for wellbore cementing is to ensure its strength and long-term integrity. To obtain high-strength cement-based materials, the influence of basalt fiber as a reinforcement was studied to create a cement slurry with high compressive and flexural strength. Deformation of the cement under loading was also investigated during the testing process. For the study, a cement plug was created using Portland cement with a water-cement ratio of 0.5. Different concentrations of basalt fiber (0.1%, 0.5%, 1%, and 2%) were added to the mix. Strength tests were carried out on the cement stone samples after 2, 7, and 14 days. The results showed that reinforcing the cement with basalt fiber significantly improved both its strength properties and plasticity. The addition of fiber led to an 11% increase in both compressive and flexural strength. Among the different fiber concentrations tested, 0.5% basalt fiber yielded the most successful outcomes, providing the highest strength characteristics for the cement stone while preserving its fluidity as a cement slurry. These findings offer valuable insights for the practical use of basalt fiber-reinforced cement slurry in constructing oil and gas wells, ensuring their durability and long-term performance.

Comparison between Different Bulk-Fill and Incremental Composite Materials Used for Class II Restorations in Primary and Permanent Teeth: In Vitro Assessments.

Several advantages, including improved aesthetics and conservative cavity preparation, made resin-based composite (RBC) a popular restorative material. However, several limitations come with RBC restorations such as the necessity for proper isolation of the tooth and an incremental layering for the material due to the limitations of the depth of cure. Despite these advantages and limitations, the usage of these restorative materials is increasingly being expanded due to the advancement made since their introduction. To overcome some of the limitations, several types of RBC restorations were developed. Four different RBC materials used for class II restorations in primary and permanent teeth were compared: Z350 XT Filtek™ Universal Restorative (ZXT), Filtek™ Bulk Fill Flowable Restorative (FBF), Beautifil-Bulk Flowable (BBF) and Tetric™ N-Flow (TNF). Flexure strength, elastic modulus, surface roughness, microhardness and microleakage were assessed using standard methods or previously published protocols. The data and differences between the groups were analyzed using One-way analysis of variance (ANOVA), Tukey's multiple comparisons, Kruskal-Wallis and Wilcoxon rank-sum (Mann-Whitney) tests. The study found that BBF (86.24 ± 7.41 MPa) and ZXT (64.45 ± 11.52 MPa) had higher flexural strength than FBF (50.89 ± 8.44 MPa) and TNF (50.67 ± 9.40 MPa), while both exhibited the highest values of surface roughness. Elastic modulus was the highest with BBF, which was not statistically significant from FBF or ZXT (p > 0.05). ZXT (109.7 ± 7.83 VH) exhibited the highest value of microhardness, which was statistically significant from the other three materials (p < 0.0001). Microleakage was assessed after thermocycling for 20,000 cycles to simulate two years in the mouth. FBF (70%) exhibited the most resistance to microleakage. Different types of RBC restorations exhibit different characteristics. The clinician needs to choose the most appropriate restorative material based on different clinical scenarios.