Tensile Strength Research Articles

Influence of Recycling and UV Exposure on the Properties of 3D Printing Polymer Materials

The use of polymer materials in various fields has increased significantly due to their ease of thermoforming and relatively low production costs. The production volume of these materials is extremely high, and according to forecasts from global statistical centers, it is expected to continue rising in the future. However, the extensive use and easy availability of polymeric materials have caused significant ecological problems. The world faces large amounts of polymer waste and environmental pollution. Plastic recycling remains challenging due to issues related to sorting polymer waste and separating it according to polymer types. Recycling certain plastics requires only a quarter of the energy needed to produce new plastic. To address this, circular economy principles should be applied to 3D printing products made from polymeric materials. A particularly wide application of these technologies is found when polymeric materials are used due to their low cost, low melting temperatures, and other advantageous properties. This paper investigates the impact of plastic recycling on the quality of 3D-printed products. During the research, samples were 3D printed and tested using both virgin and recycled PLA, ABS, and PET-G materials. The samples underwent static and dynamic tests to determine their mechanical properties, such as tensile strength, elongation, and impact resistance. The research results showed that the properties of recycled polymer materials deteriorate, with relative elongation of recycled and 3D-printed materials decreased by 16–45%. Despite this, recycled polymer materials can still be used, but it is necessary to account for the reduction in plasticity when creating products that will be exposed to dynamic loads. The impact strength is reduced by 6% for PLA, 54% for ABS, and 58% for PET-G. Additionally, the research included tests on samples printed with 3D printing technology that were exposed to UV irradiation. The results indicated similar dependences, as UV exposure also affects the reduction of material plasticity. After 66 Wh/m2 of UV radiation, the tensile strength of PET-G and PLA decreased by 17%, while ABS showed a reduction of about 5%.

Effect of Treatment Methods on Material Properties and Performance of Sawdust-Concrete and Sawdust-Polymer Composites

The circular economic approach in polymer composite research has gained acceptance for offering low-cost, high-performance solutions. Sawdust-derived composites have drawn interest as alternatives in concrete and composite fabrication, addressing housing shortages and resource depletion. Sawdust concrete (SDC) and sawdust polymer composites (SDPC) are key areas under investigation, with SDC additionally aiding in carbon reduction in building materials. However, challenges arise due to sawdust’s inherent hydrophilicity, porosity, and lower strength. This study introduces a novel approach by identifying specific chemical treatments, including alkali and silane, which effectively enhance sawdust’s compressive and tensile strengths, moisture resistance, and durability, optimizing it for structural applications. The study evaluates SDC’s compressive strength based on treatment type, concentration, and curing time, examining physical properties such as water absorption, moisture sensitivity, and fiber-matrix adhesion. The unique contribution lies in a detailed optimization analysis, revealing conditions under which sawdust reaches structural-grade performance, expanding its potential in sustainable construction. For SPDC, tensile strength improvements are assessed under various chemical compositions, showing that specific polymers form stronger fiber-matrix bonds for greater stability. Morphological studies further explore fiber-matrix compatibility, hydrophobicity, and failure mechanisms. By advancing the understanding of treatment efficacy, this review positions sawdust as a viable, low-cost material alternative, establishing a foundation for sustainable innovation in construction and bio-composite research. These findings contribute to sawdust’s potential as a practical, eco-friendly building material.

Investigating physical and mechanical properties of alumina/acrylonitrile butadiene styrene composites manufactured by fused deposition modeling

AbstractIn recent years, 3D printing technologies or additive manufacturing have gained significant attention in research and other industries. Among the various 3D printing techniques, fused deposition modeling has been the most widely adopted. This study focused on developing composite filaments by incorporating acrylonitrile butadiene styrene (ABS) with different volume percentages of aluminum oxide (alumina). The mechanical and physical properties of parts printed with these composite filaments were thoroughly evaluated. Tensile testing revealed that increasing the alumina content led to a reduction in tensile strength. At 20 vol%, tensile strength dropped by 72%. A heat deflection temperature (HDT) test indicated an 11% reduction in HDT, likely due to the defective composite structure. Thermogravimetric analysis test demonstrated improved thermal stability as alumina content increased. Linear shrinkage was measured in three directions, revealing anisotropic shrinkage patterns. Hardness tests were conducted, and a decrease was observed when the polymer was filled with alumina. Finally, the warpage was reduced by 91% as alumina content increased to 20%.Highlights Alumina/ABS composite filaments were manufactured and 3D‐printed very well. The void content in composite samples increases with alumina powders. The mechanical properties of 3D‐printed composite parts were decreased The alumina powder improves the warpage issues in 3D‐printed parts.

Fabrication of curcumin-incorporated human amniotic membrane extracellular matrix-derived scaffold to enhance full-thickness wound healing in diabetic rats.

The multifactorial nature of diabetic wounds necessitates a mixed approach for successful treatment. Compensation of degenerated wound tissue extracellular matrix (ECM) and application of anti-inflammatory and antioxidant agents have been shown to be promising. Here, an attempt was made to fabricate a biocompatible wound dressing from curcumin-incorporated human amniotic membrane (HAM) ECM-derived scaffold to accelerate diabetic wound healing in rats. Therefore, after inducing diabetes, an excisional ischemic wound was created on rat skin, then treatments were administered for a period of 21days. The main groups were the diabetic animals that received an engraftment of HAM scaffold (HAMS group) and the curcumin-incorporated HAMS (HAMS/β/C group). Evaluation at post-wounding days 7, 14, and 21 indicated that the parameters related to regeneration, including wound closure, volume of new epidermis and dermis, proliferating cells, fibroblasts, blood vessels, collagen deposition, and tensile strength, as well as transcripts of Vegf, bFgf, and Tgf-β genes of the healed wound in both HAMS and HAMS/β/C groups were considerably greater than those of the diabetic group. Conversely, the presence of inflammatory cells, i.e., neutrophils and macrophages, and the transcripts of Tnf-α and Il-1β showed a dramatic decrease in the treated groups relative to the diabetic group. Finally, compared to the HAMS group, considerable differences were found with the HAMS/β/C group in almost all evaluated parameters. Overall, these results suggest that using the complementary or synergistic effects of curcumin and HAMS could be a promising approach to improve diabetic wound healing.

Characterization of High-Performance Composite Bricks Fabricated from Recycled HDPE/PS Blends and Brick Powder

Abstract This study explores the feasibility and benefits of utilizing plastic waste in the production of construction materials, specifically composite bricks. The escalating accumulation of plastic waste poses significant environmental challenges, which necessitates innovative approaches for recycling and re-utilization to mitigate pollution and reduce landfill use. Our research focuses on the synthesis of bricks by incorporating high-density polyethylene (HDPE) and polystyrene (PS) with sand brick powder, utilizing a compatibilizer (SBS-g-MA) to enhance interfacial adhesion and mechanical integrity.
The experimental methodology involved the preparation of composite materials through melt mixing, followed by molding to form brick specimens. These were analyzed for their mechanical properties, including tensile strength, Young's modulus, and elongation at break, as well as thermal properties such as degradation temperature and crystallization behavior.
Results showed that the inclusion of sand brick powder significantly enhances the thermal stability of the composites, as evidenced by the higher degradation temperatures observed. Specifically, the degradation temperature increased from 300.59°C in pure HDPE/PS blends to 420.39°C in composites with 7% brick powder, suggesting the formation of a protective barrier against thermal decomposition. Moreover, mechanical testing revealed that composites with up to 7% brick powder exhibited improved tensile strength and Young's modulus compared to pure polymer blends.

Effect of Incorporating Natural Zeolitic Tuffs in Concrete Mixed and Cured Using Seawater

Concrete production has increasingly used seawater to overcome the challenge of freshwater scarcity. Although the use of seawater in concrete still has a controversial reputation, it is a promising application, particularly when combined with mineral admixtures such as natural zeolitic tuffs (ZT). This paper aims to investigate the effect of using locally quarried ZT on the strength of unreinforced concrete mixed and/or cured using seawater. The mix proportions of the concrete were selected to obtain the optimum combination for the M20 grade of concrete with a water-to-cement ratio of 0.69. Moreover, 150mm-cubes and cylinders of 100 mm diameter by 200mm height were cast from the concrete mixtures, which contain 0%, 5%, 7.5%, 10%, and 25% of ZT as a partial replacement of silica sand. Splitting tensile tests and compressive strength tests were conducted on these specimens at 7, 28, and 90 days. The results show the harmful effect of seawater on the strength of plain concrete (without ZT) at 7, 28, and 90 days of curing, especially when seawater is used in both mixing and curing of the concrete. However, adding ZT in seawater-based concrete improved its strength apparently, especially at early curing ages. For example, using 10% of ZT as a partial replacement of silica sand increased the compressive strength of seawater based-concrete by 105.4%, 28.3%, and 34.6% after 7, 28, and 90 days of curing, compared with concrete without ZT and produced using seawater. These results contribute to the enhancement of the sustainability of both freshwater and concrete material through the use of ZT in producing concrete, particularly in areas where freshwater is scarce or expensive.

Strength properties of concrete containing palm bunch ash–calcined anthill clay

AbstractThis study evaluated the strength properties of concrete produced with palm bunch ash–calcined anthill clay (PBA-CAC) as pozzolans. Two groups of palm bunch ashes were produced: ashes generated by burning only palm bunches (PBA) and ashes obtained by blending palm bunches and anthill clay at elevated temperatures (PBA-CAC). The PBA and PBA-CAC satisfied the requirements of Class C pozzolans. The concrete constituents were batched by mass, and the cement–fine aggregate–coarse aggregate ratio was 1:2:4. The cement content was partially substituted with PBA and PBA-CAC at 5%, 10%, 15%, 20%, and 25%, with the 0% specimen serving as the control. The concrete cubes were cured for 7, 14, 28, 56, and 90 days, whereas the concrete cylinders and beams were cured for 7, 28, 56, and 90 days. The 28th day strength values of the control specimens exceeded those of the PBA and PBA-CAC concrete specimens. By the 90th day of curing, the strength values of the specimens produced with 5% PBA and 5% PBA-CAC exceeded those of the control specimen. The PBA-CAC specimens generally had higher values of compressive strength, splitting tensile strength, and flexural strength than PBA specimens containing the same amount of pozzolan.

Experimental comparison between flattened Brazilian disc and ring tests in evaluating indirect tensile strength of two types of Gondwana sandstone

Experimental comparison between flattened Brazilian disc and ring tests in evaluating indirect tensile strength of two types of Gondwana sandstone

Synergistic effects of boron carbide and eggshell particles on mechanical and tribological properties of ultrasonic-assisted stir cast aluminium alloy based composites

Aluminium matrix composites are in high demand for their lightweight nature and favourable properties, yet issues like high thermal expansion, low microhardness or high cost often challenge them. To address these limitations, the integration of sustainable, cost-effective reinforcing agents that can enhance hardness and wear resistance can be explored, as this can broaden the application scope of these composites across various industries. The present study fabricates aluminium matrix composites with aluminium alloy (AA6063-T6) as a matrix and different wt.% (0%, 2% and 4%) of micro-sized eggshell (ES) and boron carbide (B4C) particles as reinforcements through ultrasonic-assisted stir-casting. Analysis of microstructure, mechanical and tribological properties of the fabricated composites are done and compared to those of the as-cast base alloy. Results from optical and scanning electron microscopy (SEM), together with energy-dispersive X-ray spectroscopy (EDS) analysis, revealed the uniform distribution of reinforcements in all three composites. X-ray diffraction (XRD) indicated the formation of several compounds in each composite. Among all, the as-cast base alloy exhibited the lowest porosity at 0.48%. The AA6063-T6/B4C composite demonstrated the highest hardness, with an increase of 46.08%, while the AA6063-T6/ES/B4C composite achieved the highest tensile strength, showing a 62.28% improvement compared to the as-cast base alloy. As the load increased from 20N to 60N, the wear rate of the reinforced composites rises while the coefficient of friction decreased, with the AA6063-T6/B4C composite showing the highest wear resistance.

Effect of Traffic Vibration on Compressive Strength of High-Strength Concrete and Tensile Strength of New-to-Old Concrete Interfaces

Widening existing bridges is an important way to meet the surge in traffic demand, which is often carried out in a way that does not interrupt traffic. To investigate the effect of traffic vibration on the compressive strength of high-strength concrete and the splitting strength of new-to-old concrete interfaces, the initial to final set time of high-strength concrete C60 was first investigated in this article. Then, the traffic disturbance parameters were determined. Later, the compressive strength of C60 concrete at different stages under traffic disturbance parameters was carried out. Finally, the splitting tensile strength of new-to-old concrete specimens at different stages with different loading modes was tested. The test results indicated that the compressive strength of the specimens vibrated for 3 h and cured for 3, 7, and 28 days was increased by 4.3%, 5.7%, and 11.9%, respectively; those of the specimens vibrated for 7 h and cured for 3, 7, and 28 days was decreased by 13.7%, 20.4%, and 19.9%, respectively; the effect traffic vibration on the compressive strength of the specimens vibrated for 5 h was not obvious. When loaded along the old and new concrete joint, the specimens cracked along the joint; the splitting tensile strengths of the specimen at different disturbed stages were significantly decreased. When loaded perpendicular to the joint, the specimens cured for 3 and 7 days still cracked along the joint, and the splitting tensile strengths of the specimen at different disturbed stages were significantly decreased; while the specimens cured for 28 days cracked in the direction perpendicular to the joint, the tensile strengths of the specimens at different disturbed stages were significantly decreased. This study can promote the widening and improvement of existing concrete highways and bridges, which can save resources and improve land use.

Synthesis and characterization of the chitosan-xanthan-graphene oxide film for bone regeneration using advanced cell therapy

The present study aimed to synthesize and characterize polymer films at different graphene oxide (GO) concentrations for use in advanced cell therapy. Chitosan-xanthan (CX) films were prepared and combined with GO and then assigned to the following groups: G1 – CX; G2 – CX GO 0.5%; G3 – CX GO 1.0%; and G4 – CX GO 1.5%. The films were analyzed for their structural, mechanical, and biological properties by Raman and Fourier-Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Confocal Laser Scanning Microscopy (surface roughness measurement), Tensile Strength, and in vitro Bioactivity assay. Tensile strength and surface roughness data were analyzed by one-way analysis of variance (ANOVA), followed by Tukey’s test (α = 0.05). FTIR spectroscopy showed the presence of amide I and II bands (characteristic of chitosan) and carboxyl group (characteristic of xanthan). CO bands characteristic of GO were observed in groups containing these particles. Raman spectroscopy revealed D and G bands in the GO-containing groups. Film surface morphology exhibited a homogeneous, compact, and pore-free surface. The CX group had higher tensile strength (5.89 ± 1.62 KPa) ( p < 0.05). No statistically significant difference was observed in the other GO-containing groups ( p > 0.05). The films induced the deposition of apatite crystals on their surfaces, exhibiting activity under biomineralization conditions. Graphene oxide added into chitosan-xanthan films enhanced surface roughness and bioactivity but decreased tensile strength. The synthesized CXGO films are promising for advanced cell therapy because of their physicochemical, morphological, and mechanical properties, which seem ideal for tissue regeneration.

Silver Nanoparticles (AgNPs) Incorporation into Polymethyl Methacrylate (PMMA) for Dental Appliance Fabrication: A Systematic Review and Meta-Analysis of Mechanical Properties

Silver Nanoparticles (AgNPs) Incorporation into Polymethyl Methacrylate (PMMA) for Dental Appliance Fabrication: A Systematic Review and Meta-Analysis of Mechanical Properties

Bond-Slip Behavior Between C-Shaped Steel and Foamed Concrete in CTS Composite Structural Members

The bond-slip behavior between cold-formed thin-walled steel (CTS) and foamed concrete (FC) is a critical issue in the mechanical performance of FC-filled CTS composite wall structures. Thus, this study provides experimental and theoretical research on the bond-slip behavior between CTS and FC. A total of eleven specimens were tested using push-out configurations, considering the number of web holes, foamed concrete (FC) strength, anchorage length, and CTS section splice form. A constitutive model for bond-slip was proposed, and the regression formulas for accurately predicting the characteristic bond strength between CTS and foamed concrete were established. A finite element model was developed to investigate the bond-slip mechanism at the interface between CTS and FC. The bond-slip constitutive model accurately fits the experimental and finite element results. The results indicate that the ultimate bond strength of the specimens increases with the number of web holes; when the number of web holes reaches two, the ultimate bond strength is 155.4% of that of the non-perforated specimens. As the concrete strength increases from 3.43 MPa to 11.26 MPa, the ultimate bond strength of specimens with two web holes improves by 23.1%, while non-perforated specimens have a 54.7% enhancement. When the anchorage length is extended from 200 mm to 400 mm, the ultimate bond strength decreases by 29.3%. Additionally, when steel sections are joined in a double-span I form, the bond strength increases by 91.6% and 95.8% compared to the single-span form and the double-span box form, respectively.

Finite element analysis of soil-nailed vertical excavation in fine-grained soils in an urban area

This paper presents analysis and discussion of an urban vertical excavation, with the soil nailing technique, in fine-grained soils with high plasticity. The excavation was numerically evaluated using finite element analysis (FEA) using a 3D finite element model (FEM). Several field and laboratory soil investigations were conducted, interpreted and used in the FEA. The FEM model was calibrated using instrumentation and monitoring results during the soil nailing construction. Analyses were conducted focusing in horizontal displacements, nail pullout strength, nail tensile load, soil stress state, and tensile load at the nail head. The results showed that the behavior of the soil nailing retaining wall in fine-grained soils differs significantly from what is typically reported in the literature for non-cohesive soils. The high apparent cohesion of the fine-grained soil resulted in good performance, with reduced horizontal displacements on the face and lower tensile loads in the nails and at their head.

Mechanical and Tribological Properties of AA2024 reinforced Al2O3 and ZrO2 Hybrid Composite

Abstract Hybrid metal matrix composite (HMMC) alloys are a very attractive material for excellent mechanical and tribological performance, and their properties can be easily customized by varying reinforcement types and amounts. This research investigated the mechanical and tribological properties of an Aluminium Alloy (AA) 2024 reinforced with 2 wt.% Al2O3 and (2, 4, 6) wt.% ZrO2 hybrid composites. The presence and distribution of reinforcements in the stir-casted samples were confirmed by SEM, EDS, and elemental mapping. The tribological tests were conducted on a pin-on-disc under dry and wet conditions using Taguchi’s L9 orthogonal array. The SAE 20w40 oil and SAE 20w40 oil mixed with TiO2 nano additive are lubricants. The hardness and tensile strength increase linearly with the addition of a single and continue to increase with multiple reinforcements. The HMMC exhibits a maximum hardness and tensile strength of 107 BHN and 209.281 MPa, respectively. The experimental results show that the dry condition’s wear rate is much higher than that of the composites lubricated with SAE 20w40, especially SAE 20w40 with TiO2 nano additive. Compared to the base material, AA2024 reinforced with 2 wt.% of Al2O3 and 6 wt.% of ZrO2 exhibited an enhanced wear resistance of 0.0002353 mm3/min and COF of 0.118 with nano lubricant which is 40% and 21% higher than base lubricant.

Preparation and characterization of Pistacia atlantica oleo-gum-resin-loaded electrospun nanofibers and evaluating its wound healing activity in two rat models of skin scar and burn wound

BackgroundA growing body of research is dedicated to developing new therapeutic agents for wound healing with fewer adverse effects. One of the proceedings being taken today in wound healing research is to identify promising biological materials that not only heal wounds but also vanish scarring. The effectiveness of nanofibers like polyvinyl alcohol (PVA), in improving wound healing can be related to their unique properties. Pistacia atlantica Desf. subsp. kurdica (Zohary) Rech. f. (PAK) [Anacardiaceae], also known as “Baneh” in traditional Iranian medicine, is one of the most effective herbal remedies for the treatment of different diseases like skin injuries due to its numerous pharmacological and biological properties, including anti-inflammatory, antioxidant, and anti-bacterial effects.PurposeOur study aimed to evaluate the wound-healing activity of nanofibers containing PVA/PAK oleo-gum-resin in two rat models of burn and excision wound repair.Material and MethodsPVA/PKA nanofibers were prepared using the electrospinning method. Scanning electron microscope (SEM) images and mechanical properties of nanofibers were explored. Diffusion and releasing experiments of nanofibers were performed by the UV visible method at different time intervals and up to 72 h. The animal models were induced by excision and burn in Wistar rat’s skin and the wound surface area was measured during the experiment for 10 and 21 days, respectively. On the last day, the wound tissue was removed for histological studies, and serum oxidative factors were measured to evaluate the antioxidant properties of the PVA/PKA. Data analysis was performed using ImageJ, Expert Design, and statistical analysis methods.Results and discussionPVA/PKA nanofibers were electrospun at different voltages (15, 18, and 20 kV). The most suitable fibers were obtained when the nozzle was positioned 15 cm away from the collector, with a working voltage of 15 kV, and an injection rate of 0.5 mm per hour, using the 30:70 w/v PKA gum. In the SEM images, it was found that the surface tension of the polymer solution decreased by adding the gum and yield thinner and longer fibers at a voltage of 15 kV with an average diameter of 96 ± 24 nm. The mechanical properties of PVA/PKA nanofibers showed that the presence of gum increased the tensile strength and decreased the tensile strength of the fibers simultaneously. In vivo results showed that PVA/PKA nanofibers led to a significant reduction in wound size and tissue damage (regeneration of the epidermal layer, higher density of dermal collagen fibers, and lower presence of inflammatory cells) compared to the positive (phenytoin and silver sulfadiazine) and negative control (untreated) groups. Wound contraction was higher in rats treated with PVA/PKA nanofibers. Additionally, antioxidative serum levels of catalase and glutathione were higher in the PVA/PKA nanofiber groups even in comparison to positive control groups.ConclusionPistacia atlantica oleo-gum-resin-loaded electrospun nanofibers potentially improve excision and burn models of skin scars in rats through antioxidative and tissue regeneration mechanisms.

Toward Sustainable 3D-Printed Sensor: Green Fabrication of CNT-Enhanced PLA Nanocomposite via Solution Casting

The current study explores, for the first time, an eco-friendly solution casting method using a green solvent, ethyl acetate, to prepare feedstock/filaments from polylactic acid (PLA) biopolymer reinforced with carbon nanotubes (CNTs), followed by 3D printing and surface activation for biosensing applications. Comprehensive measurements of thermal, electrical, rheological, microstructural, and mechanical properties of developed feedstock and 3D-printed parts were performed and analyzed. Herein, adding 2 wt.% CNTs to the PLA matrix marked the electrical percolation, achieving conductivity of 8.3 × 10−3 S.m−1, thanks to the uniform distribution of CNTs within the PLA matrix facilitated by the solution casting method. Rheological assessments paralleled these findings; the addition of 2 wt.% CNTs transitioned the nanocomposite from liquid-like to a solid-like behavior with a percolated network structure, significantly elevating rheological properties compared to the composite with 1 wt.% CNTs. Mechanical evaluations of the printed samples revealed improvement in tensile strength and modulus compared to virgin PLA by a uniform distribution of 2 wt.% CNTs into PLA, with an increase of 14.5% and 10.3%, respectively. To further enhance the electrical conductivity and sensing capabilities of the developed samples, an electrochemical surface activation treatment was applied to as-printed nanocomposite samples. The field-emission scanning electron microscopy (FE-SEM) analysis confirmed that this surface activation effectively exposed the CNTs to the surface of 3D-printed parts by removing a thin layer of polymer from the surface, thereby optimizing the composite’s electroconductivity performance. The findings of this study underscore the potential of the proposed eco-friendly method in developing advanced 3D-printed bio-nanocomposites based on carbon nanotubes and biopolymers, using a green solution casting and cost-effective material extrusion 3D-printing method, for electrochemical-sensing applications.

Effect of Bio‐Based Plasticizers From Modified Vegetable Oils in a New Formulation of PVC Materials

ABSTRACTThis study investigates the performance of polyvinyl chloride (PVC) plasticized with diisononyl phthalate (DINP), rapeseed oil epoxidized ester (ROE), and rapeseed oil carbonated ester (ROC). The formulations were evaluated for surface resistance, wettability, migration, mechanical properties, and resistance to aging and thermal degradation. PVC/ROC exhibited the highest surface resistance of 1.5 × 1016 Ω, indicating superior electrical insulation. Wettability tests showed PVC/ROE with the highest contact angle at 63°, while PVC/ROC and PVC/DINP demonstrated lower contact angles of 44° and 43°, respectively. Migration tests revealed that PVC/ROC had the lowest migration rates: 0.1% in distilled water and 1.5% in 95% ethanol. Mechanical testing under algae exposure demonstrated that PVC/ROC achieved the highest tensile strength of 43 MPa and a strain at break of 200%. After 1008 h of thermo‐oxidative aging, PVC/ROC retained superior tensile strength and hardness, while PVC/ROE showed a slight decrease. PVC/ROC also demonstrated improved thermal stability at 255°C compared with DINP (245°C). These results confirm that ROC is an effective bio‐based plasticizer, providing enhanced mechanical properties, reduced migration, and greater durability compared to conventional DINP, offering a sustainable alternative for diverse PVC applications in medical, automotive, and packaging industries.

Development and optimization of parameters for HVOF sprayed Al2O3 and ZrO2 blended aluminum coating on 316L SS

Abstract A significant number of gas turbines, aircraft engines, bearings, and automotive engines operating under a wide temperature range fail frequently due to fatigue and surface oxidation. Thus, a new coating formulation 40Al-35Al2O3-25ZrO2 was deposited on 316L SS substrate through the high velocity oxygen-fuel (HVOF) thermal spray coating method. The number of passes, spray distance and oxygen flow rate were varied by using Taguchi L9 array to achieve an optimized coating with higher hardness, less porosity, and roughness. The coating phase analysis, microstructure, elemental composition, microhardness and nano hardness were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), Vickers microhardness and nano indentation testing. The sample 5 prepared at spray distance of 20 cm and oxygen/acetylene ratio of 2 exhibited optimal hardness (1972 HV1), tensile strength (6.463 GPa), porosity (0.75%) and roughness (6.2 μm) due to α-Al2O3 and t-ZrO2 phases. Oxygen flowrate was the influential parameter contributing 48.71% to microhardness and 42.41% to roughness, while spray distance with contribution 51.62% was influential parameter for porosity.

Airborne-Particle Abrasion vs. Hydrofluoric Acid Etching of Dental Ceramics: Impact on the Tensile Bond Strength

This study evaluated whether airborne-particle abrasion could be an alternative to hydrofluoric acid etching as a pretreatment for the adhesive bonding of silicate ceramic restorations. Feldspar (FEL; n = 100), lithium silicate (LiSi; n = 100), and zirconia (ZrO2; (n = 80) substrates were CAD/CAM-fabricated and airborne-particle-abraded with Al2O3 (25 µm or 50 µm of mean particle size) at pressures of 0.05 or 0.1 MPa. The controls included FEL (60 s) and LiSi (20 s) etched with hydrofluoric acid. The surface free energy (SFE) and roughness (Ra) were measured. For the tensile bond strength (TBS), surfaces were conditioned using a primer (Monobond Plus) and luted to a resin composite (Variolink Esthetic). TBS was assessed initially (24 h, 37 °C water storage) and after thermocycling (5/55 °C, 10,000×). Statistical analysis (SPSS, V29) was performed using a one-way ANOVA, post hoc Scheffé, and a two-group t-test (p = 0.05). Abrasion with 50 µm and 0.1 MPa induced the highest Ra values across the materials (62.5 ± 3.88 µm). ZrO2 exhibited a higher TBS (35.4–49.5 MPa) than FEL and LiSi. For aged LiSi, the specimens treated at 0.1 MPa showed a higher TBS (18.7 ± 9.0 MPa) than those treated at 0.05 MPa, regardless of the particle size. The etched and aged FEL showed a higher SFE but a lower TBS compared to abrasion. Al2O3 particle abrasion (25 or 50 µm at 0.1 MPa) may replace etching for silicate-based ceramics, while 50 µm is recommended for ZrO2 at either pressure.