Flexural Strength Values Research Articles

Effects of Different Fiber Sizes in PLA/Carbon Fiber Composites on Mechanical Properties

This study assessed the morphology and chemical composition of coir coconut husk carbon fiber, as well as the impact of fiber diameters on the physical and mechanical properties of polylactic acid composites. Researchers are studying polylactide acid, a biodegradable material. This eco-friendly material’s excellent features, generated from sustainable and renewable sources, have drawn many people. Malaysia’s high coconut fiber output made coir husk a popular commodity. Coconut fibers are lignin, cellulose, and hemicellulose. Alkaline treatment eliminates hemicellulose, oil, wax, and other contaminants from coir fibers and removes lignin. Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were used to examine the treated coconut fibers’ chemical modification analysis and morphology. Coconut coir husk was carbonized to produce carbon fiber using a furnace operated at 300°C for 2 hours. Fiber and polylactic acid were mixed in different fiber sizes (0, 53 μm, 75 μm, and 212 μm) via extrusion and injection processing techniques. The results showed that the alkali treatment reduced the hydroxyl (-OH) group and separated the area from the carbonyl (C=O) group of coconut coir husk, which changed the filler’s hydrophilicity. The fiber size of 212 μm was discovered to have the highest tensile and flexural strength values. According to testing, the modified material structure had a better surface fill-matrix bond. Thus, generalized fiber sizing and characterization methods were developed. Regardless of the matrix, this method can characterize natural fiber strength and interfacial shear strength of varied diameters and solid contents.

Comparative Evaluation of the Flexural Strength of Heat-Activated Polymethyl Methacrylate Denture Base Resin With and Without 0.2% by the Weight of Silver Nanoparticles Cured by Conventional and Autoclave Methods: An In Vitro Study.

Heat-activated polymethyl methacrylate (PMMA) is the most common and widely accepted denture base material. Two important drawbacks are the development of denture stomatitis and the high incidence of fracture of denture bases. The present study investigated the effect of adding 0.2% by weight of silver nanoparticles (AgNps) and using the autoclave method of terminal boiling on the flexural strength of heat-activated PMMA denture base resin. A total of 40 samples of heat-activated PMMA blocks were divided into four groups, with 10 samples (n = 10) in each group. Group 1 consisted of unmodified heat-activated PMMA resin (PMMA-1) polymerized by the conventional method of terminal boiling (conventional curing); Group 2 consisted of 0.2% by weight AgNPs added to heat-activated PMMA resin (PMMA-2) polymerized by conventional curing; Group 3 consisted of PMMA-1 polymerized by the autoclave method of terminal boiling (autoclave curing); and Group 4 consisted of PMMA-2 polymerized by autoclave curing. The flexural strength was tested using a universal testing machine. Descriptive statistics were expressed as mean ± SD and median flexural strength. Kruskal-Wallis ANOVA with Mann-Whitney U post hoc test was applied to test for statistical significance between the groups. The level of significance was set at p<0.05. The results showed a statistically significant reduction in flexural strength in Group 2 compared to Group 1. The samples from Group 4 showed a statistically significant increase in flexural strength compared to Group 2. The Group 4 denture base had the highest flexural strength (115.72 ± 7.27 MPa) among the four groups, followed by Group 3 (104.16 ± 4.85 MPa). The Group 1 samples gave a flexural strength of 101.45 ± 3.13 MPa, and Group 2 gave the lowest flexural strength (85.98 ± 3.49 MPa) among the four groups tested. The reduction in flexural strength of the heat-activated PMMA denture base after adding 0.2% by weight of AgNP as an antifungal agent was a major concern among manufacturers of commercially available denture base materials. It was proved in the present study that employing the autoclave curing method of terminal boiling for the polymerization of 0.2% by weight of AgNp-added heat-activated PMMA denture base resulted in a significantly higher flexural strength compared to the conventional curing method of terminal boiling for polymerization. Unmodified heat-activated PMMA gave higher flexural strength values when polymerized by autoclave curing compared to the conventional curing method of terminal boiling.

Mechanical properties, cytotoxicity, and protein adsorption of three-dimensionally printable hybrid resin containing zwitterionic polymer and silicate-based composites for dental restorations

ObjectiveTo evaluate the mechanical and biological properties of three-dimensionally (3D) printable resins filled with 2-methacryloyloxyethyl phosphorylcholine (MPC) and silicate-based composites and compare with those of a commercially available 3D-printable resin for definitive restorations. MethodsA group of 3D-printable hybrid resins (HRs) filled with 6 wt% MPC and three different compositions of silicate-based composites (barium silicate to zirconium silicate ratios: 1.50:1 for HR1, 0.67:1 for HR2, and 0.25:1 for HR3) were prepared. The HR groups were compared with the commercially available unfilled 3D-printable resin (CR) marketed for definitive restorations in terms of flexural strength and modulus, fracture toughness, surface roughness, Vickers hardness, light transmittance (all, n = 15), cytotoxicity, and protein adsorption (both, n = 3). All data were analyzed by using non-parametric Kruskal–Wallis and Dunn's tests (α=0.05). ResultsThe HR groups had significantly higher flexural strength, modulus, fracture toughness, and hardness values than the CR (P < 0.001). HR3 had the highest surface roughness and light transmittance among the groups (P ≤ 0.006). None of tested resins showed cytotoxicity. Both HR2 and HR3 showed significantly lower protein adsorption than the CR, with a difference of approximately 60% (P ≤ 0.026). ConclusionBoth HR2 and HR3 exhibited superior mechanical properties (flexural strength, flexural modulus, fracture toughness, and Vickers hardness), light transmittance, and protein-repellent activity than the CR, with no impact on cytotoxicity. Clinical significanceThe MPC/silicate-based composite-filled resins may be a suitable alternative for definitive restorations, given their higher mechanical properties and promising biological properties to prevent microbial adhesion and subsequent biofilm formation, as well as their non-cytotoxic properties.

Effect of Post-Printing Conditions on the Mechanical and Optical Properties of 3D-Printed Dental Resin.

This study aimed to evaluate the flexural strength (FS), surface wear, and optical properties of 3D-printed dental resins subjected to different post-printing conditions. A total of 240 specimens (2 × 2 × 25 mm³) were 3D-printed using resin materials for permanent (VaresoSmile Crown Plus) VSC and temporary (VaresoSmile Temp) VST restorations. Specimens underwent five post-printing conditions: no post-printing cure; post-cured in a Form Cure curing unit; Visio Beta Vacuum; Ivoclar Targis; or heat-cured (150 °C) for 30 min. Each group of specimens (n = 24) was tested either directly after post-curing, after 24 h of dry storage, or following hydrothermal accelerated aging in boiling water for 16 h. The three-point bending test was used to evaluate the FS. The two-body wear test was performed on 50 disc-shaped specimens (n = 5/group). Surface gloss and translucency were measured for permanent VSC specimens (n = 5/group). SEM/EDS and statistical analyses were performed. The Form Cure device yielded the highest FS and lowest wear depth (p < 0.05). Hydrothermal aging significantly reduced FS. There were no statistical differences in FS and wear values between materials subjected to same post-printing conditions. VSC groups exhibited similar optical properties across different post-printing treatments. Post-printing treatment conditions had a significant impact on the FS and wear of the 3D-printed resin, while optical properties remained unaffected.

Conceptual Design and Materials Selection of the FDM Composites for Passenger Vehicle’s Spoiler

One of the additive manufacturing techniques available is Fused Deposition Modeling (FDM), which offers advantages in design flexibility, cost-effectiveness, and the ability to produce intricate designs. Therefore, FDM for the 3D-printed vehicle’s car spoiler is a subject that can be explored. The FDM technology can significantly reduce time and cost before mass production, and the vehicle’s car spoiler was used as the case study in this research. The research investigates the mechanical properties of various commercial PLA composite filaments, addressing the lack of specifications provided by manufacturers. Testing four types of filaments—PLA/bamboo, PLA/coconut, PLA/wood, and PLA/metal. This research also emphasizes the conceptual design generation and selection for the passenger vehicle’s spoiler. Five design concepts were generated using the morphological chart for the passenger vehicle’s spoiler. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was used as the decision-making tool. As a result, PLA/metal, with 53.65 MPa and 70.23 MPa, showed the highest tensile and flexural strength values, respectively. Design concept 5 with the infill pattern of rib + I was the best from the finite element analysis (FEA) using SolidWorks simulation software. Finally, the TOPSIS technique revealed PLA/metal as the best PLA composite filament for car spoilers, scoring first in performance score with a value of 0.5774. This study demonstrates that by using a systematic approach, researchers may choose the best design concept and material choice by combining the conceptual design, experimental, simulation, and TOPSIS methods.

Durability Assessment of Eco-Friendly Bricks Containing Lime Kiln Dust and Tire Rubber Waste Using Mercury Intrusion Porosimetry

The global challenge faced due to the impact of the construction industry on climate change, along with the issues surrounding sustainable waste disposal, has necessitated various research on using waste products as eco-friendly alternatives in construction. In this study, the avoidance of waste disposal through landfills in Australia was encouraged by incorporating lime kiln dust (LKD) and tire rubber waste (TRW) into masonry mixes to manufacture green bricks. Furthermore, the investigations in this article highlight the use of mercury intrusion porosimetry (MIP) to determine the durability of the LKD-TRW bricks when exposed to freeze–thaw (F-T) cycles by examining the pore size distribution within the bricks. The LKD waste was blended with ground granulated blast furnace slag (GGBFS) at a 70:30 blending ratio and combined with the TRW in stepped increments of 5% from 0 to 20% to produce these eco-friendly bricks. The compressive strength (CS), flexural strength (FS), frost resistance (FR), pore size distribution according to mercury intrusion porosimetry (MIP), and the water absorption (WA) properties of the bricks were assessed. The CS and FS values at 28 days of curing were recorded as 6.17, 5.25, and 3.09 MPa and 2.52, 2, and 1.55 MPa for 0, 5, and 10% TRW contents, respectively. Durability assessments using the F-T test showed that the bricks produced with 0% TRW passed as frost-resistant bricks. Furthermore, the results from the MIP test showed a total pore volume of 0.033 mL/g at 3 µm pore size for the 0% TRW content, further confirming its durability. Hence, the 0% LKD-TRW bricks can be utilized in cold regions where temperatures can be as low as −43 °C without deteriorating. Lastly, WA values of 7.25, 11.76, and 14.96% were recorded for the bricks with 0, 5, and 10% TRW, respectively, after the 28-day curing period. From all of the results obtained from the laboratory investigations, the LKD-TRW bricks produced with up to 10% TRW were within the satisfactory engineering requirements for masonry units.

Flexural Properties of Three Novel 3D-Printed Dental Resins Compared to Other Resin-Based Restorative Materials

To evaluate the flexural strength and flexural modulus of three recently introduced 3D-Printed resins and compare them with the flexural properties of other well known, already commercialized, and extensively used resin based dental materials. Three 3D-printed dental resins, a fiber-reinforced epoxy resin, a heat-cured bis-acrylate-based composite resin, two conventional CAD/CAM PMMA, and a graphene-reinforced CAD/CAM PMMA, were selected for this study. Ten prismatic-shaped specimens (2 × 2 × 25 mm) were fabricated for each material (n = 10). All specimens underwent a three-point bending test using a universal testing machine and were loaded until fracture. Flexural strength (MPa) and flexural modulus (MPa) mean values were calculated and compared using the on ranks One-Way ANOVA test. Scanning electron microscope analysis of the 3D-printed resins was performed. Significantly different flexural properties were recorded among the tested materials. The fiber-reinforced epoxy resin exhibited the highest flexural strength (418.0 MPa) while, among the 3D-printed resins, the best flexural strength was achieved by Irix-Max (135.0 MPa). Irix-Plus and Temporis led to the lowest mean flexural strength values (103.9 MPa and 101.3 MPa, respectively) of all the CAD/CAM milled materials, except for the conventional PMMA by Sintodent (88.9 MPa). The fiber-reinforced epoxy resin also showed the highest flexural modulus (14,672.2 MPa), followed by the heat-cured bis-acrylate composite (10,010.1 MPa). All 3D-printed resins had a higher flexural modulus than the conventional PMMA materials. CAD/CAM fiber-reinforced epoxy resin excels in flexural strength, with Irix-Max showing promising flexural properties, which could encourage its use for permanent restorations. Caution is needed with Irix-Plus and Temporis due to their lower flexural strength compared to other traditional materials.

Post-processing of a 3D-printed denture base polymer: Impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity

ObjectivesTo investigate the impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity of an additively manufactured denture base polymer. MethodsThe tested specimens were prepared by digital light processing (DLP). A centrifugation method (CENT) was used to remove the residual uncured resin. In addition, the specimens were post-processed with different post-rinsing solutions: isopropanol (IPA), ethanol (EtOH), and tripropylene glycol monomethyl ether (TPM), respectively. A commercial heat-polymerized polymethyl methacrylate was used as a reference (REF). First, the values of surface topography, arithmetical mean height (Sa), and root mean square height (Sq) were measured. Next, flexural strength (FS) and modulus were evaluated. Finally, cytotoxicity was assessed using an extract test. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's multiple comparison test for post-hoc analysis. ResultsThe Sa value in the CENT group was lower than in the IPA, EtOH, TPM, and REF groups (p < 0.001). Moreover, the CENT group had lower Sq values than other groups (p < 0.001). The centrifugation method showed a higher FS value (80.92 ± 8.65 MPa) than the EtOH (61.71 ± 12.25 MPa, p < 0.001) and TPM (67.01 ± 9.751 MPa, p = 0.027), while affecting IPA (72.26 ± 8.80 MPa, p = 0.268) and REF (71.39 ± 10.44 MPa, p = 0.231). Also, the centrifugation method showed no evident cytotoxic effects. ConclusionsThe surfaces treated with a centrifugation method were relatively smooth. Simultaneously, the flexural strength of denture base polymers was enhanced through centrifugation. Finally, no evident cytotoxic effects could be observed from different post-processing procedures. Clinical significanceThe centrifugation method could optimize surface quality and flexural strength of DLP-printed denture base polymers without compromising cytocompatibility, offering an alternative to conventional rinsing post-processing.

Alternative material recommendation for facade cladding: High silica-containing stonepaste ceramics

This study investigated the potential of using stonepaste ceramics, which were widely preferred as a coating and decoration material on the facades of architectural buildings in ancient times and continues to be produced on a workshop scale today as a cladding material on building facades. Stonepaste ceramics, made from a mixture prepared with a high amount of crystalline quartz as well as frit, plastic clay, and bentonite raw materials, were hand-shaped and sintered at 930 °C after glazing. The physico-mechanical properties of stonepaste ceramics, their behaviour under various environmental conditions (resistance to chemicals, frost, and thermal shock), and their microstructures have been characterized. The characterization results were compared with the properties of commonly used facade cladding materials. It was determined that stonepaste ceramics had a very low firing shrinkage value (2.84 %) compared to that of other ceramic cladding materials, a higher water absorption value (11.79 %) than that of porcelain tiles and floor tiles, and close to wall tiles, and a flexural strength value (33.64MPa) higher than wall tiles and close to porcelain tiles despite the high-water absorption value. Ten cycles of thermal shock resistance showed that the body and glaze layer of the stonepaste ceramic material are well bonded to each other, and there is no significant thermal expansion mismatch between them. One hundred cycles of freeze-thaw conditions indicated that the stonepaste ceramic had good adhesion and thermal expansion compatibility between the glaze and the body but only chipping damage under the action of tensile forces caused by the freezing of water entering the pores of the body. In terms of behaviour against various chemicals, stonepaste ceramics were found to be highly resistant to high and low concentrations of household chemicals, swimming pool salts, and alkalis but less resistant to low concentrations of HCl and citric acid and high concentrations of HCl and lactic acid compared to other chemicals. The results show that stonepaste ceramics, despite their high-water absorption potential, have properties close to those of traditional ceramic tiles and, like these materials, can serve for significant periods in various environmental conditions when used as facade cladding. Consequently, it has been revealed that stonepaste ceramics can be used as a facade cladding material in sustainable, long-lasting, contemporary architectural facades thanks to their technical and protective properties.

Flexural strength and degree of conversion of universal single shade resin-based composites

Background/purposeRecently, a group of universal single-shade resin-based composites (RBCs) has been developed to simplify the process of shade selection. Excellent mechanical and physical properties are crucial for the ultimate success and clinical longevity of restorations. Therefore, evaluating the properties of the single-shaded RBCs is imperative. This study aimed to determine the flexural strength (FS) and degree of conversion (DC) of universal single-shade RBCs. Materials and methodsIn this study, four commercial RBCs were used; three universal single-shade RBCs; Omnichroma (OC), Charisma® Diamond ONE (CD), and Vittra APS Unique (VU), and a conventional nanohybrid composite Filtek™ Z250 XT (FT) which was used as a control. Sixty composite beams and 40 composite discs were used for FS and DC, respectively. A universal test machine with a three-point bending test was used to measure the FS, whereas the DC was measured using a Fourier-transform infrared spectrometer (FTIR). Three fractured specimens from each resin composite group were qualitatively analyzed using scanning electron microscopy. ResultsANOVA was used to compare the mean values of FS and DC among the four RBCs (OC, CD, VU, and FT). Highly significant differences were observed in the mean FS and DC values (F = 673.043, p < 0.001 and F (=782.4, p < 0.0001), respectively. The highest FS was observed in the CD group, followed by FT and VU groups; the lowest value was observed in the OC group. In addition, a statistically significant difference was identified in DC values. The highest DC value was observed in VU, followed by OC and CD, and the lowest DC value was observed in FT. ConclusionUniversal single-shade RBCs demonstrated a good FS, except for OC, which exhibited a significantly low FS. The DC of the universal single-shade RBCs was higher than that of the conventional nanohybrid composite restorative material.

Effects of silica fume and rice husk ash contents on engineering properties and high-temperature resistance of slag-based prepacked geopolymers

Geopolymer slurries can be favored to achieve a sustainable approach in prepacked aggregate concretes. This study presented here investigated experimentally the effect of silica fume (SF) and rice husk ash (RHA) on the high-temperature resistance of slag-based sustainable prepacked geopolymers. In the production of prepacked aggregate geopolymers (PAGs), ground granulated blast furnace slag (GGBFS) was utilized as the main aluminosilicate-rich precursor material, and SF and RHA were replaced with GGBFS in various contents including 7.5 % and 15 %. The physical, mechanical, and microstructural properties of specimens cured at 35 °C and 70 °C for 8 h were determined comparatively. Residual compressive strength and mass loss of mixtures exposed to elevated temperatures (150 °C, 300 °C, and 600 °C) were determined to observe high-temperature effects. The results revealed that the properties of PAGs were affected considerably by curing temperature and precursor type. The maximum oven-dry density of 2244 kg/m3 with RHA content of 7.5 % was obtained at 70 °C curing temperature. Specimens produced with RHA tended to absorb more water under both heat curing conditions and the highest water absorption of 10.2 % with RHA content of 7.5 % was obtained at 35 °C curing temperature. The compressive strength of PAGs varied between 13.7 and 28.10 MPa, and flexural strengths varied between 1.48 and 2.74 MPa. Increasing curing temperature improved the strength properties of PAGs, and in general, the 8-h compressive and flexural strength values of SF samples were relatively higher. The application of elevated temperature to the PAG mixtures caused a significant reduction in both compressive strength and mass loss. Among the specimens cured at 35 °C, the specimens with RHA showed relatively better high-temperature performance in terms of compressive strength, while the specimens with SF cured at 70 °C showed better performance. PAG specimens produced with RHA showed the best high-temperature performance against mass loss. According to the results obtained in the given study, these recycled wastes could be used to improve the physico-mechanical properties and high-temperature performance of slag-based PAGs.

Exploring the Potential of Promising Sensor Technologies for Concrete Structural Health Monitoring.

Structural health monitoring (SHM) is crucial for maintaining concrete infrastructure. The data collected by these sensors are processed and analyzed using various analysis tools under different loadings and exposure to external conditions. Sensor-based investigation on concrete has been carried out for technologies used for designing structural health monitoring sensors. A Sensor-Infused Structural Analysis such as interfacial bond-slip model, corroded steel bar, fiber-optic sensors, carbon black and polypropylene fiber, concrete cracks, concrete carbonation, strain transfer model, and vibrational-based monitor. The compressive strength (CS) and split tensile strength (STS) values of the analyzed material fall within a range from 26 to 36 MPa and from 2 to 3 MPa, respectively. The material being studied has a range of flexural strength (FS) and density values that fall between 4.5 and 7 MPa and between 2250 and 2550 kg/m3. The average squared difference between the predicted and actual compressive strength values was found to be 4.405. With cement ratios of 0.3, 0.4, and 0.5, the shear strength value ranged from 4.4 to 5.6 MPa. The maximum shear strength was observed for a water-cement ratio of 0.4, with 5.5 MPa, followed by a water-cement ratio of 0.3, with 5 MPa. Optimizing the water-cement ratio achieves robust concrete (at 0.50), while a lower ratio may hinder strength (at 0.30). PZT sensors and stress-wave measurements aid in the precise structural monitoring, enhanced by steel fibers and carbon black, for improved sensitivity and mechanical properties. These findings incorporate a wide range of applications, including crack detection; strain and deformation analysis; and monitoring of temperature, moisture, and corrosion. This review pioneers sensor technology for concrete monitoring (Goal 9), urban safety (Goal 11), climate resilience (Goal 13), coastal preservation (Goal 14), and habitat protection (Goal 15) of the United Nations' Sustainable Development Goals.

Flexural behavior of SS316-based metal matrix composite prepared through microwave heating

SS316 is the most commonly used material among the existing stainless steels. SS316-based composite materials provide tailor-made stuff to the various automotive and machinery components due to their competent properties. In the current work, SS316, EWAC, and Cr7C3 powders have been selected for the development of cast specimens in the domestic microwave applicator. The cast of the SS316+15EWAC+5Cr7C3, SS316+15EWAC+10Cr7C3, and SS316+15EWAC+15Cr7C3 compositions has been prepared using a novel technique of microwave hybrid heating. The sample size of 30 × 6 mm2 has been used for flexural strength analysis. The flexural modulus, flexural strength, maximum load, strain at break, and strain at peak load have been tested on a universal testing machine. The maximum values of flexural strength, flexural modulus, peak load, and microhardness were found 469.86 MPa, 10,2321.79 MPa, 4510.65 N, and 585.93 ± 203.33 HV respectively for SS316+15EWAC+15Cr7C3 cast, and maximum strain at peak load and the maximum strain at breaking load were 3.07 and 4.29% respectively for SS316+15EWAC+10Cr7C3 cast. The highest microhardness of 615 HV has been obtained at the carbide phase in the case of SS316+15EWAC+15Cr7C3 cast. The XRD presented the leading peaks of σ-Fe, μ-Fe3Ni2, τ-Cr23C6, α-MoNi4, γ-Mo2C, and β-Fe5C2. The microstructural morphology of the composite casting revealed the proper coalescence of the matrix, homogeneous dispersion of reinforcements, dendrites formation, and equiaxed grain growth. Overall the metallurgical and mechanical properties of the composite cast were improved.

Contribution of cellulose nanofibrils on the strengthening and toughening of neat and blended polylactide specimens; and the differences after 3D-printing

The main purpose of this study was to use “green materials” approach by investigating effects of only 1 wt% Cellulose Nanofibrils (CNF) on the strengthening and toughening of neat and blended polylactide (PLA) biopolymer matrix. For this purpose, first of all effects of CNF were investigated in PLA/CNF biocomposite specimens. After blending of PLA with 10 phr bio-based thermoplastic polyester (b-TPE) elastomer, effects of CNF were investigated also for this PLA/b-TPE/CNF ternary biocomposite specimens. Mechanical tests revealed that due to the efficient strengthening and toughening mechanisms, CNF increased flexural strength of PLA by 33%, while b-TPE increased fracture toughness of PLA by 104%. When CNF and b-TPE were incorporated together, synergism in the strength and toughness values were occurred. All bioblend and biocomposite specimens were produced by using the same “melt mixing” technique in a laboratory size twin-screw extruder, and their test specimens were shaped by conventional “compression molding”. Since shaping by “3D-printing” is frequently used in the biomedical sectors, another distinctive aim of this study was to reveal whether there were any differences in the strength and toughness values of specimens after their 3D-printing. It was observed that due to the “textured” structure of 3D-printed specimens, their flexural strength values were approximately 20% lower, while fracture toughness values were approximately 20% higher.

Fabrication of mechanical durable novolac matrix composites with recycled and cost-effective candle-soot nano particles

Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.

Industrial sustainable Fabrication, SEM Characterization, mechanical Testing, ANOVA analysis of PP-PETF recycled Composites: Artificial intelligence and deep learning studies for nuclear shielding applications

The sustainable processing of polymeric waste is required innovation. In this article, polypropylene (PP)- polyethylene terephthalate fiber (PETF) composite materials were fabricated according to the International Organization for Standardization (ISO 9001–2 and 2008) for commercial manufacturing using extrusion and injection molding. The variations of 0, 10, 30, and 40 % of PETF loadings were utilized for mechanical properties’ optimization. The results indicate that tensile strength, strain, and young’s modulus of elasticity were in the range of 22–25 MPa, 3–5 % and 870–1167 MPa. Correspondingly, the values of flexural strength, strain and modulus constant were in the range of 39–40 MPa, 9–12 % and 1909–2140 MPa, respectively. The impact energies were in the range of 2.6–3.4 kJ/m2. Thermally, the PP-PETF composites were found stable. The scanning electron microscope characterization, presence of induced micro defects, optimum flake structure, analysis of variance, deep learning, and artificial intelligence studies predict the utilization of PP-PETF composites for manufacturing of panels and sheets regarding static loading bearing applications. The reported technical strategies can be utilized as a reference processing technique for industrial manufacturing of PP-PETF based recycled composite products.

Effect of gastric acids on the mechanical properties of conventional and CAD/CAM resin composites - An in-vitro study

ObjectivesDental erosion in patients with gastroesophageal reflux disease (GERD) is a current and frequent condition that may compromise the mechanical properties and clinical durability of resin-based composites (RBCs). This study assessed the mechanical properties of conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) RBCs subsequent to simulated gastric acid aging. Materials and methodThree conventional and three CAD/CAM composites were assessed. They were divided into an experimental group (exposed to simulated gastric acid aging) and a control group (no aging). Both groups were analyzed for Vickers microhardness (VHN), wear and flexural strength over a period of six months. The failure rate probability for each RBC was calculated through the Weibull cumulative distribution function (m). Statistical analysis was conducted using repeated measures ANOVA, 3-way ANOVA, a non-parametric Kruskal-Wallis and U Mann-Whitney tests (α = 0.05). ResultsThe mechanical properties of all the RBCs dropped significantly after aging (p < 0.05). Lower VHN and flexural strength values, along with greater wear values were evident in the experimental groups, though the effects of the treatment varied between RBCs. The Weibull m of all the RBCs decreased over time. ConclusionConventional RBCs might show greater reduction in mechanical properties compared to CAD/CAM RBCs when exposed to gastric acid attack. Thus, CAD/CAM composites may represent a suitable choice for the treatment of patients presenting erosive issues.

Mechanical Properties of Direct Composite Resins and CAD/CAM Composite Blocks

The widespread application of CAD/CAM technology in contemporary dentistry led to the development of promising restorative materials, such as resin composite blocks (RCBs). Thus, the present study aims to evaluate the mechanical properties of RCBs, comparing this material to the direct composite resin from the same manufacturer. Samples retrieved from three CAD/CAM resin composite blocks (Tetric CAD (TC), Ivoclar Vivadent, Grandio blocs (GB), VOCO GmbH and Brilliant Crios (BC), Coltene/Whaledent) and four direct composite resins (Tetric EvoCeram (TEC), Ivoclar Vivadent, GrandioSO (GS), VOCO GmbH, Brilliant EverGlow Translucent (BET) and Universal Shade (BEU), Coltene/Whaledent) were submitted to three-point bending flexural test and Vickers microhardness test. The resulting data of the flexural strength were analyzed using one-way ANOVA considering Bonferroni correction for post hoc tests (α = 0.05). The flexural modulus and Vickers microhardness results were analyzed using Welch’s ANOVA considering Games–Howell correction for post hoc tests (α = 0.05). Regarding results, flexural strength and flexural modulus values ranged from 81.1 MPa (BEU) to 246.5 MPa (GB) and 10.6 GPa (BEU) to 20.3 GPa (GB), respectively. GS (121.2) and GB (136.2) groups were associated with the highest microhardness values. According to the post hoc tests, statistically significant differences in flexure strength were found in RCBs (BC, GB, and TC) compared to all direct composite resins. Flexural modulus and Vickers microhardness of RCBs (BC, GB, TC) were also significantly different from the direct composite resin (BET, BED, and TEC), except when comparing GS and GB for microhardness. In conclusion, differences between RCBs and direct composite resins were observed regarding flexural strength, flexural modulus, and microhardness, revealing that RCBs have enhanced mechanical properties compared to direct composite resins.

Effect of curing mode of resin composite cements on water sorption, color stability, and biaxial flexural strength

ObjectivesTo determine whether water sorption and solubility of a recently introduced self-adhesive cement is comparable to two clinically tested resin composite cements after thermal aging, and if this is affected by the curing mode. Whether water sorption is correlated with color difference and biaxial flexural strength was also investigated. MethodsWater sorption and solubility of three resin composite cements {RelyX Universal (RUV), (Panavia V5 (PV5), Panavia SA plus (PSA)} were measured after thermal aging. Disk-shaped specimens were either light-cured or autopolymerized (n = 15 per group). Color difference ΔE00 and biaxial flexural strength were also obtained. ResultsSorption was highest for RUV (auto: 54.9 ± 9.0 µg/mm3, light: 49.7 ± 4.9 µg/mm3), followed by PSA (auto: 37.7 ± 1.4 µg/mm3, light: 34.5 ± 1.1 µg/mm3) and PV5 (auto: 21.7 ± 0.7 µg/mm3, light: 22.1 ± 0.4 µg/mm3). Light-curing reduced solubility values, particularly for RUV (from 60.7 ± 20.8 µg/mm3 to 6.4 ± 0.8 µg/mm3). Color differences of ΔE00 > 1.8 (considered clinically not acceptable) were noted after aging for RUV and PSA. Sorption and ΔE00 values after aging were correlated linearly (R2 = 0.970). Biaxial flexural strength values were highest for PV5 (light: 153.4 ± 15.9 MPa; auto: 133.2 ± 18.0 MPa) and lowest for RUV (light: 99.3 ± 12.8 MPa; auto: 35.1 ± 8.3 MPa). SignificanceLight-curing has beneficial effects on sorption, color stability, and biaxial flexural strength of resin composite cements. Cements containing 2-hydroxymethacrylate such as RUV and PSA are more prone to water sorption and color changes.

Color Alterations, Flexural Strength, and Microhardness of 3DPrinted Resins Treated in Different Coloring Agents.

Purpose This study evaluated the color alterations, flexural strength and microhardness properties of two different 3D-printed permanent crown resins. Materials and Methods Samples were produced from two different 3D Print permanent crown resins: Group 1 (Saremco Crowntec; Saremco, Switzerland), Group 2 (P-crown Version 2; Senertek, Turkey). Color changes (ΔE values), flexural strenght and vickers hardness number of the samples were calculated. Data were analyzed with Shapiro-Wilk normality test, Independent-t test, and Mann Whitney-U tests. Significance level was accepted as P<0.05. Results ΔE values for red wine were found to be significantly higher in Group 1 (6.43Å}2.26; P<0.001). The flexural strength values (MPa) of Group 1 were significantly higher than Group 2 in all three solutions (P<0.001). There was no significant difference between the VHN values of the samples kept in wine and coffee solutions (P= 0.271; 0.827). Conclusion 3D printing resins are affected at different levels by coloring solutions. Microhardness and flexural strength of 3D print samples kept in different coloring agents are different.In the use of 3D printing resins, product selection should be made by taking into account the individual factors such as the eating and drinking habits of the patients and the physical properties expected from the sample.