MPa Flexural Strength Research Articles

Reinforcement of polylactic acid with bioceramics (alumina and YSZ composites) and their thermomechanical and physical properties for biomedical application

AbstractFused Deposition Modeling (FDM) is one of the most popular Additive Manufacturing (AM) techniques widely used in different fields, including the medical sector. FDM uses different thermoplastic polymers to fabricate the desired shapes. However, there is a need to enhance the mechanical properties of neat biopolymers with the help of reinforcements that can be used in medical applications. This work investigates the thermomechanical, physical, and biological properties of PLA‐based composites fabricated using FDM. PLA‐based bio‐ceramics (Al2O3 and Yttria Stabilized Zirconia [YSZ]) filaments have been used to prepare tensile, compression, and flexural specimens. Scanning electron microscopy has been performed to reveal the fracture characteristics of the composite specimens. Besides this, the feasibility of the polymer composite for biomaterial applications has also been analyzed. The results show that PLA/Al2O3 has 30.44, 55.2, and 83.73 MPa tensile, compressive, and flexural strength, respectively. The present study also shows that the reinforcement of PLA with bioceramics also led to a reduction in wear and Coefficient Of Friction (COF) at varying loads.

Effectiveness of Rattan Fiber as a Reinforcing Material in Polymer Matrix Composites: An Experimental Study

ABSTRACT It has been proposed that rattan fiber (RA) as reinforcement can be a promising candidate for the fabrication of composites. In present research, composites were fabricated by reinforcing rattan fibers with poly(vinyl) alcohol (PVA) matrix. Its various properties (mechanical, thermal, and morphological properties) were evaluated and compared with that with neat PVA. Surface treatments of fibers were carried out to have a better compatibility with PVA matrix. The mechanical properties were found to increase at the early stage with the increase in treated rattan fiber content till optimum (24 wt%) fiber loading and thereafter declines. At 24 wt% (optimum) fiber loading the mechanical properties obtained were 48.722 MPa of tensile strength, 45.72 MPa of flexural strength, 1.57 GPa of young’s modulus and 5.89 kJ/m2 of impact strength. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) were used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVA matrix. It was found that composites fabricated from 24 wt% fiber content shows superior mechanical properties as well as thermal properties as compared with other fabricated composites and can be used for making partition boards, light weight packaging boxes, and furniture.

Physical and mechanical properties of porcelain tiles made from raw materials in Uganda

This study was intended to determine the physicomechanical properties of porcelain tiles made from raw materials in Uganda, hitherto not used for the same. The raw materials were mixed in proportions of 40–60% clays, 30–40% feldspar and 10–30% sand, the goal was to identify a mixture with properties that meet the ISO 13006 standards after firing. Test tile samples were formulated at a pressure of 40 MPa and fired from 1050 to 1250 °C in steps of 50 °C. A firing rate of 40 °C per minute and a dwell time of 2 h were applied. The microstructures and phase analysis of the fired samples were studied using a scanning electron microscope (SEM) and X-ray diffractometer (XRD), respectively. The XRD analysis revealed mullite and quartz as crystalline phases present in the fired bodies. At 1150 °C, the SEM micrograph depicted few, short and thick mullite fibers. At 1200 °C, the mullite population increased. The nature of the fibers (long, fine and more interlocking) resulted in an increase in flexural strength. A further rise in temperature had no significant change on the nature of the fibers and flexural strength of the samples. The best properties; flexural strength (33 MPa) and water absorption (0.08%) were exhibited at 1200 °C by samples with 30–40% kaolin, 30–40% feldspar, 20% ball clay and 10% sand. The results indicate that these samples are comparable to the ISO 13006 standards for porcelain tiles which are ≥ 35±2 MPa flexural strength and <0.5% water absorption. The other mix proportions did not meet these standards, specifically in terms of flexural strength (<25 MPa).

Effect of graphite and Mn3O4 on clay-bonded SiC ceramics for the production of electrically conductive heatable filter

Electrically conductive porous SiC ceramics are attracting substantial attention due to their application in heatable filters, vacuum chuck, and semiconductor processing parts, etc. The main problem is their high processing cost. Ideal candidates from an engineering ceramic perspective will be mechanically durable and have the required electrical properties with sufficiently low fabrication costs. To decrease the sintering temperature, kaolin has been added, but it tended to render the material an insulator. Graphite was used to effectively decrease the electrical resistivity. Additionally, manganese oxide was used to decrease the quantity of kaolin (the component that leads to an insulator material after sintering) and decrease the electrical resistivity while maintaining the mechanical properties. In our study, we found that SiC with 35% kaolin, 20% graphite and 10% manganese oxide can produce samples with 6.5 × 10−1 Ω cm electrical resistivity and 43.5 MPa flexural strength at a low sintering temperature of 1200 °C.

Physical Characterization of Bismuth Oxide Nanoparticle Based Ceramic Composite for Future Biomedical Application.

Employment and the effect of eco-friendly bismuth oxide nanoparticles (BiONPs) in bio-cement were studied. The standard method was adopted to prepare BiONPs-composite. Water was adopted for dispersing BiONPs in the composite. A representative batch (2 wt. % of BiONPs) was prepared without water to study the impact of water on composite properties. For each batch, 10 samples were prepared and tested. TGA (thermogravimetric analysis) performed on composite showed 0.8 wt. % losses in samples prepared without water whereas, maximum 2 wt. % weight losses observed in the water-based composite. Presence of BiONPs resulted in a decrease in depth of curing. Three-point bending flexural strength decreased for increasing BiONPs content. Comparative study between 2 wt. % samples with and without water showed 10.40 (±0.91) MPa and 28.45 (±2.50) MPa flexural strength values, respectively, indicating a significant (p < 0.05) increase of the mechanical properties at the macroscale. Nanoindentation revealed that 2 wt. % without water composites showed significant (p < 0.05) highest nanoindentation modulus 26.4 (±1.28) GPa and hardness 0.46 (±0.013) GPa. Usage of water as dispersion media was found to be deleterious for the overall characteristics of the composite but, at the same time, the BiONPs acted as a very promising filler that can be used in this class of composites.

Saliva Influence on the Mechanical Properties of Advanced CAD/CAM Composites for Indirect Dental Restorations.

This study aims to evaluate the microstructural and mechanical properties of three commercial resin-based materials available for computer-aid design and manufacturing (CAD/CAM)-processed indirect dental restoration: LavaTM Ultimate Restorative (LU), 3M ESPE; Brilliant Crios (BC), COLTENE and CerasmartTM (CS), GC Dental Product. The three types of resin-based composite CAD/CAM materials were physically and mechanically tested under two conditions: directly as received by the manufacturer (AR) and after storage under immersion in artificial saliva (AS) for 30 days. A global approximation to microstructure and mechanical behaviour was evaluated: density, hardness and nanohardness, nanoelastic modulus, flexural strength, fracture toughness, fracture surfaces, and microstructures and fractography. Moreover, their structural and chemical composition using X-ray fluorescence analysis (XRF) and field emission scanning electron microscopy (FESEM) were investigated. As a result, LU exhibited slightly higher mechanical properties, while the decrease of its mechanical performance after immersion in AS was doubled compared to BC and CS. Tests of pristine material showed 13 GPa elastic modulus, 150 MPa flexural strength, 1.0 MPa·m1/2 fracture toughness, and 1.0 GPa hardness for LU, 11.4 GPa elastic modulus; 140 MPa flexural strength, 1.1 MPa·m1/2 fracture toughness, and 0.8 GPa hardness for BC; and 8.3 GPa elastic modulus, 140 MPa flexural strength, 0.9 MPa·m1/2 fracture toughness, and 0.7 GPa hardness for CS. These values were significantly reduced after one month of immersion in saliva. The interpretation of the mechanical results could suggest, in general, a better behaviour of LU compared with the other two despite it having the coarsest microstructure of the three studied materials. The saliva effect in the three materials was critically relevant for clinical use and must be considered when choosing the best solution for the restoration to be used.

Fabrication and Characterization of Acrylic Acid Treated Rattan Fiber Reinforced Polyethylene Terephthalate Composites for Packaging Industries

ABSTRACT In the present work, treated and untreated novel RA reinforced PET thermoplastic polymer composites were developed. The fibers were chemically modified before fabrication of the composites to have a better fiber-matrix bonding. Thermo-mechanical properties of the composites were studied. An enhancement in mechanical properties were found at the beginning phase with the increase in treated rattan fiber content till optimum fiber loading (i.e 20 wt%) thereafter the properties decline. At 20 wt% fiber loading the mechanical properties obtained were 67.89 MPa of tensile strength, 83.29 MPa of flexural strength, 3.98 GPa of young’s modulus, and 24.18 kJ/m2 of impact strength. Different properties of the composites were thoroughly studied and the composites fabricated at 20 wt% of fiber content reveals excellent mechanical and thermal properties and found very much suitable for packaging applications.

Experimental and statistical analysis of robotic 3D printing process parameters for continuous fiber reinforced composites

3D printing technology has gradually taken its place in many sectors. However, expected performance cannot be obtained from the structural parts with this method due to the raw material properties and constraints of Cartesian motion systems. This technology cannot replace structural parts produced by traditional manufacturing methods. In order to avoid these constraints, it is preferred to use continuous fiber reinforced polymer composites in many areas such as automotive and aerospace industries due to their low weight and high specific strength properties. These automated composite manufacturing methods currently have limited production of geometric shapes due to the need for additional molds and production as flat surfaces. To overcome all these constraints, fiberglass reinforced ultraviolet ray-curing polymer matrix composite material are selected for robotic 3 D printing process and various parameters are examined. Fiber-polymer combination and layer structure formation was examined. Scanning Electron Microscopy (SEM) images of sections of 3 D printed test samples were taken and fiber resin curing was examined. The nozzle diameter, printing speed, fiber density and Ultra Violet (UV) light intensity parameters, which will provide effective 3 D printing process, are optimized with the Taguchi method. Tensile strength, flexural strength and izod impact values are considered as result parameters for optimization. It was found that it would be appropriate for 3D printing with a 1.0 mm nozzle diameter, 600 tex fiber density, 4 UV light, 600 mm/min printing speed. With these 3D printing process parameters, approximately 125 MPa tensile strength and 450 MPa flexural strength can be obtained. With this study, support and contribution was provided to researchers, composite producers, tool manufacturer and literature who want to use and develop this 3D printing process.

Effect of Ti and its compounds on the mechanical properties and microstructure of B4C ceramics fabricated via pressureless sintering

The addition of Ti and its compounds particles has the potential to effectively enhance the fracture toughness of B4C ceramics. However, the influence of different Ti-based compounds on B4C ceramics has not been extensively studied. In this work, B4C–TiB2 multiphase ceramics were prepared by adding 5% Ti or its compounds (TiO2, TiB2 or TiC) in B4C and the effects of the additives on the B4C ceramics were studied. For this purpose, we adopted a sintering process carried out in situ in the absence of pressure at a temperature of 2250 °C for 1 h. It was evident from the results that the additives are capable of enhancing the sintering densification characteristics and the properties exhibited by B4C, as opposed to single-phase B4C ceramics. Additionally, different additives have varied effects on the microstructures and mechanical properties of B4C–TiB2 multiphase ceramics. The results of the study indicate that the TiC-added sample exhibits the most optimal mechanical properties, with 4.52 MPa m1/2 fracture toughness, 344.0 MPa flexural strength, 26.2 GPa hardness, and 516.0 GPa elastic modulus.

Magnetic and mechanical characterization of Al-MWCNT-Fe-Ni hybrid metal matrix composites

This paper aimed to synthesize the aluminum (Al) based magnetic hybrid composites by using iron nanoparticles (Fe: 16–28 vol%), nickel nanoparticles (Ni: 2 vol%) and multi-wall carbon nanotubes (MWCNT: 2 vol%) as reinforcements. The magnetic, mechanical, electrical properties were investigated. The highest saturation magnetization of 79.21 emu/g was given by the composite with high volume fraction of iron nanoparticles. However, with an addition of nickel (2 vol%) in Al-MWCNT-Fe, the magnetic properties were decreased. A reduction of power losses up to 41.5% was achieved by using Ni 2 vol%. It was also found that the composites with greater aluminum content had better tensile strength with the highest strength of 68.5 MPa and better flexural strength. The greatest hardness of HV 74 was achieved by increasing the Fe content. The electrical resistivity varied between 1354 µΩ.cm and 2450 µΩ.cm, which is higher than that of commercial aluminum and some of its alloys.

Structural and Mechanical Properties of Alumina-Zirconia (ZTA) Composites with Unstabilized Zirconia Modulation

Zirconia toughened alumina (ZTA) ceramics are very promising materials for structural and biomedical applications due to their high hardness, fracture toughness, strength, corrosion and abrasion resistance and excellent biocompatibility. The effect of unstabilized ZrO2 on the density, fracture toughness, microhardness, flexural strength and microstructure of some Zirconia-toughened alumina (ZTA) samples was investigated in this work. The volume percentage of unstabilized ZrO2 was varied from 0% - 20% whereas sintering time and sintering temperature were kept constant at 2 hours and 1580°C. The samples were fabricated from nanometer-sized (α-Al2O3: 150 nm, monoclinic ZrO2: 30 - 60 nm) powder raw materials by the conventional mechanical mixing process. Using a small amount of sintering aid (0.2 wt% MgO) almost 99.2% of theoretical density, 8.54 MPam? fracture toughness, 17.35 GPa Vickers microhardness and 495.67 MPa flexural strength were found. It was observed that the maximum flexural strength and fracture toughness was obtained for 10 vol% monoclinic ZrO2 but maximum Vickers microhardness was achieved for 5 vol% ZrO2 although the maximum density was found for 20 vol% ZrO2. It is assumed that this was happened due to addition of denser component, phase transformation of monoclinic ZrO2 and the changes of grain size of α-Al2O3 and ZrO2.

Optimization of phosphate/kaolinite microfiltration membrane using Box–Behnken design for treatment of industrial wastewater

The present work reports the preparation and characterization of flat ceramic membrane via dry pressing method made from natural phosphate as based material and kaolinite as additive to enhance membrane characteristics. Response surface methodology based on Box–Behnken design was used to optimize the preparation conditions notably amount of kaolinite (5–15 wt%), sintering temperature (900–1000 °C) and time of sintering (2–4 h). The optimized membrane has 40.2 MPa of flexural strength, 41.3% of porosity, 1045 L h−1 m−2 bar−1 of permeability and 0.35 µm of average pore size. The phosphate/kaolinite membrane was subjected to the filtration of industrial textile wastewater and it showed excellent performance as microfiltration membrane. It is able to remove 98.99% of turbidity, 69.39% of total organic carbon, 74% of chemical oxygen demand and 77.11% of biological oxygen demand.

Mechanical and conductive performance of electrically conductive cementitious composite using graphite, steel slag, and GGBS

AbstractElectrically conductive cementitious composite (ECCC) can be utilized in traffic detection, structural health monitoring (SHM), and pavement deicing. Graphite is a popular conductive filler given its outstanding electrical resistance behavior, but its flat micro‐surface decreases the friction resistance, reducing mechanical strength. However, slag solids can substitute part of the graphite with their considerable conductivity and superior mechanical characteristics. In this research, 27 ECCC composites are developed incorporated by combined graphite powder (GP), blast furnace slag (GGBS), and steel slag (SS). Flexural, unconfined compressive strength (UCS) experiments, and resistance experiments with failure mode evaluations are carried out to explore the influence of proposed conductive fillers with different fractions. Results show the graphite strongly improves conductivity but dramatically reduces mechanical performance. Both steel slag and GGBS reduced the compressive and flexural strength after their replacement ratio exceeded 20%. Additionally, compared with GGBS, SS demonstrated a better influence on mechanical and conductive performance. A 15 wt% ratio of GGBS, 20 wt% of SS, and 4 wt% of GP are explored as the optimum design with 3.4 MPa of flexural strength, 36 MPa of compressive strength, and 7,779 Ω cm of resistance. Lastly, a microstructural investigation is conducted to explore the mechanical and conductive mechanism of ECCC.

Surface modification of bamboo fiber with sodium hydroxide and graphene oxide in epoxy composites

AbstractBamboo fibers (BFs) have high mechanical properties and are candidate reinforcement for epoxy matrix composites. However, to improve performance, good fiber‐matrix interaction is required. In this work, unidirectional long BF reinforced epoxy composites at fiber volume content of 22%, 40%, and 50% were made by compression molding. The 40 v% untreated BF reinforced composites exhibited 107% and 439% increase for flexural strength and modulus, respectively, compared to neat epoxy. Sodium hydroxide (NaOH) treatment was used to modify the surface of the BFs, and then the NaOH modified BFs were coated with graphene oxide (GO). The 40 v% NaOH modified BF composites showed an improvement from 259.9 to 327.5 MPa for flexural strength and from 16.7 to 21.5 GPa for flexural modulus, compared to 40 v% untreated BF composites. Slight improvement in properties up to 334.6 MPa for flexural strength and up to 23.8 GPa for flexural modulus was achieved for composites made of 40 v% NaOH/GO modified BF. Surface modification of BF after the NaOH and NaOH/GO treatment was confirmed by X‐ray photoelectron spectroscopy and by scanning electron microscopy, which showed differences on the fiber surface morphology and on the composite fracture surface. This BF surface modification approach with GO has potential to impart other properties beyond mechanical to produce multifunctional composite and lead to the use of sustainable plant fibers as alternatives to synthetic fibers.

Ramie-glass fiber reinforced epoxy composites: Impact of walnut content on mechanical and sliding wear properties

Abstract The current research work is based on the effects of walnut content on mechanical and wear property of ramie-glass fiber epoxy composites. Four different variations of hybrid polymer composites were fabricated by varying walnut content range from 0 wt% to 9 wt%, while keeping ramie and glass fibre fixed (at 5 wt%). Results predict that the addition of walnut content successfully enhances the mechanical properties, and higher values (62.59 MPa for tensile strength and 55.52 MPa for flexural strength), was attained at 6 wt% and 9 wt% respectively. While the maximum hardness (45.43 HV) was achieved at 9 wt% walnut content. Furthermore, the sliding wear behaviour of composites was examined by using a pin-on-disc setup and Taguchi optimization technique. Design of experiment (L16) was generated by selecting different control factors (sliding velocity, normal load, and sliding distance) and revealed that the sliding velocity and walnut content were attaining more significant as compared to other factors.

Preparation of high-performance transparent glass-fiber reinforced composites based on refractive index-tunable epoxy-functionalized siloxane hybrid matrix

Fiber reinforced polymer composites (FRPs) are widely utilized in various industrial fields due to their remarkable mechanical properties and low cost fabrication. However, typical FRPs cannot concurrently fulfill optical transparency and high mechanical strength, which are essential for transparent electronics and automotive applications. Here, we report a transparent FRP (GFRH) that exhibits high opto-mechanical properties by incorporating reinforced glass-fibers into refractive index-tunable epoxy-functionalized siloxane hybrid materials. To achieve transparent composites, we precisely control the refractive index of the siloxane matrix by adding an epoxy cross-linkable hardener. We compare the opto-mechanical properties of the GFRP according to various conditions in terms of curing method (thermal- and UV-curing), fiber content (from 0 to 25 wt% of matrix), fiber length (from 0.08 to 3 mm), and fiber type (filament mat, glass-fabric, chopped strands glass-fibers, and milled glass). Finally, to obtain high-performance GFRP, we further optimize the composite structure with short fiber (5 wt% of chopped strands glass-fibers) and long fiber (10 layers of glass-fabric). The optimized composite exhibits high optical transparency (80% @ 550 nm) and mechanical properties (251 MPa flexural strength, 9 GPa flexural modulus and 3 H pencil hardness). Our transparent composite has significant potential for the application of FRPs to transparent electronics and automotive devices.

Formation, characterization and suitability analysis of polymer matrix composite materials for automotive bumper

Abstract The conventional bumper of an automobile has numerous failures hence there is a necessity to replace the existing bumper material into composite material to save the vehicle and human life. In this paper, layers of Aramid fiber with different interior angles are combined to create a composite plate to boost the mechanical properties of the aramid composite. Here, the composites are made-up by using a hand layup method and various mechanical properties have been investigated. Also, the morphological analysis was done to look at the interior structure of the tested specimen of the composite. It’s observed that composite has a high tensile strength of 147 MPa and high flexural strength of 86.8 MPa proved that the aramid composite bumper material is extremely suitable for automobiles.

Novel bio-inspired three-dimensional nanocomposites based on montmorillonite and chitosan

In this study, inspired by nacre-like structural natural shells, novel three-dimensional (3D) nanocomposites based on natural nanoplatelets of montmorillonite (MMT) and polysaccharide of chitosan (CS) were prepared with solution intercalation and self-assembly process. The CS-intercalated-MMT nanoplatelets units acted as “bricks” and CS molecules acted as “mortar”, arranging in fairly well-ordered layered structure. With addition of glutaraldehyde (GA) and Pd2+ cations, synergistic toughening and strengthening effects of covalent and ionic bonds could be achieved. The best mechanical properties of the prepared 3D nanocomposites were observed as 5.6 KJ/m2 (impact strength), 3.3 GPa (flexural modulus), and 65.8 MPa (flexural strength), respectively, which showed higher toughness but lower flexural properties than natural pearl mussel shells. Nevertheless, both the impact and flexural properties of the prepared 3D nanocomposite were much higher than the other natural shell, i.e. green grab shell. Besides conventional methods characterizations, the nacre-like structure of the artificial 3D nanocomposite was further evidenced with positron annihilation lifetime spectroscopy characterizations. This work might facilitate a versatile platform for developing green 3D bionanocomposites with fairly good mechanical properties.

Low-cost ceramic microfiltration membrane made from natural phosphate for pretreatment of raw seawater for desalination

A novel ceramic microfiltration (MF) membrane was prepared from natural phosphate and its properties were thoroughly characterized. An investigation of the effect of sintering temperature on the features of phosphate membrane was carried out in the range from 900 to 1100 °C. The optimized membrane sintered at 1000 °C exhibits 697 L h−1 m-2 bar−1 of permeability, 25.6 % of porosity, 0.26 μm of average pore size and 19.7 MPa of flexural strength. When evaluated for filtration of raw seawater as a potential pretreatment for reverse osmosis desalination, the prepared membrane reduced total organic carbon (TOC) and turbidity by 73 and 98 %, respectively, as well as reducing silt density index (SDI) from 5.41 to 3.25. Furthermore, the fouling mechanism and the flux recovery were also studied. Finally, simple cleaning of the prepared membrane performed after the MF experiment led to recover 74 % of its original water flux.

Valorization of phosphate mine waste rocks as aggregates for concrete

The phosphate industry produces great amounts of waste-rocks during their mining activities in extraction and beneficiation steps. Waste-rocks are stored immediately on extraction sites or in the vicinity of treatment facilities. Different types of waste-rocks are generated, yet this paper discusses the use of stone-removal waste-rocks as aggregates for concrete. Starting from the chemical and mineralogical composition, those waste-rocks were characterized by different techniques. Common geotechnical tests were performed to assess the aggregates properties. Then, those aggregates were used in concrete formulation as a full replacement of natural aggregates in order to test their mechanical behavior in comparison to a reference concrete, using compressive, flexural and splitting tensile strengths as parameters to evaluate the concrete performance according to the required standards.Those aggregates indicated a 41% Los Angeles coefficient, 43% Micro Deval coefficient and 5.20% Water Absorption coefficient. The WRAM concrete has indicated an average of 12 MPa of compressive strength, 1.3 MPa of flexural strength and 2.65 MPa of splitting tensile strength at 28 days.