Tensile Strength Of Samples Research Articles

Antimicrobial Activity of a Titanium Dioxide Additivated Thermoset

The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.

Sustainable copper oxide/Tragacanth gum bionanocomposites with multi‐purpose catalytic activities on textile

AbstractIn this study, a bionanocomposites layer was created on polyester textile through the insitu synthesis of copper nanoparticles using copper acetate in an alkaline solution and Tragacanth gum polymer. The chemical structure and surface morphology of samples were studied by XRD, FTIR, XPS, SEM, and EDX patterns. Moreover, the photocatalytic and antibacterial features, cytotoxicity, the release of nanoparticles, color coordinates, water absorption, thermal behavior, and tensile strength of samples were investigated. In addition, the effect of polymer coating on the created properties on the surface of samples was explored. Based on the obtained results, the prepared fabric with copper oxide/Tragacanth gum bionanocomposites created the fairly suitable photo, bio, hydro, and heat‐catalytic activities granting environment safety.

Microbiological, physicochemical and structural characteristics of natural salted casings treated with antibacterial agents

SummaryThis study aimed to investigate the effects of antibacterial agent ultrasonic immersion on the quality of salted casings in terms of microorganism, physicochemical characters and structure characteristics. The results showed that citric acid immersion had the most significant effect as compared to that of control samples, with a reduction of 1.00, 1.65 and 1.66 log CFU g−1 in Staphylococcus, Halophile and Psychrophiles compared to control samples respectively. Citric acid and tea polyphenol treatment increased the elongation at break of casings by 11.3% and 10.4%, and the most significant increase in the tensile strength of samples with chitosan oligosaccharide was 13.7%. Meanwhile, all samples were not discriminative in colour, collagen solubility, water solubility, thermal swelling and thermal shrinking rate. Furthermore, a compact and dense casing surfaces found by the scanning electron microscopy (SEM) images after antibacterial agent treatment. Therefore, antibacterial agent immersion has the potential to control microorganisms’ growth, improve mechanical properties and extend the application field of salted casings.

Using biodegradable organic salt for cotton garment dyeing to reduce effluent pollution

AbstractThe replacement of inorganic salt and alkali in the reactive dyeing of cotton textiles with organic biodegradable compound has been explored in recent years. We report the use of organic salt, tetra sodium salt of glutamic acid diacetic acid (GLDA‐Na4) in the batchwise dyeing of cotton garment as an exhausting and fixing agent. The reactive dye, CI Reactive Black 5 was selected for the present study. The results revealed that the maximum K/S value of 25.5 and fixation of 90.74% was obtained using GLDA‐Na4 at laboratory scale experiments. Furthermore, the effluent samples test results demonstrated considerably reduced total dissolved solids (TDS) and chemical oxygen demand (COD) contents with GLDA‐Na4 in comparison to the inorganic chemicals. The colourfastness to light, rubbing and washing have demonstrated similar ratings with GLDA‐Na4 and inorganic chemicals. The tensile strength of samples was enhanced by using GLDA‐Na4.

Synthesis, characterization, and properties of silicone grafted epoxy/acrylonitrile butadiene styrene/graphene oxide nanocomposite with high adhesion strength and thermal stability

AbstractTo improve thermal, mechanical and adhesion properties, epoxy resin was modified with methyl phenyl silicone (MPS), acrylonitrile butadiene styrene (ABS) and graphene oxide (GO). In order to increase compatibility and stability, MPS intermediate was grafted on epoxy resin through condensation reaction. Transmission electron microscopy images showed well dispersion of GO particles in the system proving successfully preparation of the MPS grafted epoxy/ABS/GO nanocomposite. Single lap shear strength for steel‐epoxy/carbon fiber composite joint in sample containing 15% MPS and 2% ABS improved up to 108% compared to neat epoxy. Such an improvement occurred when only 5% MPS, 2% ABS and 0.1% GO were used showing GO could decrease required content of modifiers in this case. Tensile strength of sample containing 5% MPS and 2% ABS was 49.89 MPa and it reached 55.23 MPa by adding 0.1% GO while it was 37.12 MPa in pure epoxy. Nanocomposite modified sample had a residual char of 20 wt%. at 600°C and increment of 30°C in initial degradation temperature and 7°C in maximum degradation temperature compared to pure epoxy. These finding beside 23% increasing in calculated activation energy using Kessinger's and FWO method's proved significantly improved thermal stability of modified epoxy resin. Scanning electron microscope images of fractured surface of specimens showed micro size domains obtained by phase separation cause toughness improvement and crack energy absorption.

Calcia-doped ceria hybrid coating functionalized PBO fibers with excellent UV resistance and improved interfacial compatibility with cyanate ester resins

Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers display weak outdoor stability and reliability due to their poor UV resistance and chemically inert surface. In this work, calcia-doped ceria (Ce0.8Ca0.2O1.8) nanoparticles was fabricated via chemical co-precipitation method, and the novel Ce0.8Ca0.2O1.8/P(S-co-BCB-co-MMA) organic–inorganic hybrid coating was then designed and prepared for surface functionalization of PBO fibers (PBO@P-Ce0.8Ca0.2O1.8). Organic-inorganic hybrid coating presents high surface roughness and excellent UV resistance. When the concentration of Ce0.8Ca0.2O1.8 nanoparticles with the particle size of about 50 nm is 0.6 wt%, PBO@P-Ce0.8Ca0.2O1.8–3 fibers (sample 4, 0.6 wt%) present the best interfacial bonding strength with modified bisphenol A cyanate (BADCy) resins, the single fiber pull-out strength between sample 4 and modified BADCy resins reaches the maximum value of 4.6 MPa, 48.4% higher than that of pristine PBO fibers (sample 0, 3.1 MPa). Meanwhile, the tensile strength of sample 4 after 288 h UV aging is increased from 1.4 GPa (PBO fibers) to 4.1 GPa. Overall, functionalized PBO fibers in this work demonstrate higher surface activity, excellent UV resistance and improved interfacial bonding strength with modified BADCy resins, which provides a new idea for functionalizing the surface activity and UV resistance of high-performance polymer fibers.

Effects of γ irradiation on the structure, physical and mechanical properties of a series of tetrafunctional epoxies modified DGEBA/DDS

In some nuclear applications, epoxy materials have become increasingly appealing. However, radiation-induced structural changes often deteriorate properties. Thus, the long-term stability of epoxies after exposure to radiation has to be evaluated. Irradiation induced changes in three tetrafunctional epoxy modified DGEBA/DDS were reported. Irradiation leads to changes in chemical structure and appearance, i.e., darkening in color and reduction in transparency. Irradiated samples show two absorption centers, and both the bending and tensile strengths of samples, which are modified by the tetrafunctional epoxy that has a diphenylsulfone spacer, maintain high values even after 2.8 MGy irradiation. γ irradiation leads to chain scission and decreases Tg; however, Tgs of irradiated samples modified with tetrafunctional epoxies were still higher than 220 °C. Results show that addition of tetrafunctional epoxies improves Tg of DGEBA/DDS after exposure to radiation. Irradiation-induced chain scissions also increase the heterogeneity of the cured network. Although ray reduces the thermal stability, the thermal and mechanical properties are adequate for many applications.

Physical and mechanical degradation behaviour of semi-crystalline PLLA for bioresorbable stent applications

This study presents a systematic evaluation of the physical, thermal and mechanical performance of medical-grade semi-crystalline PLLA undergoing thermally-accelerated degradation. Samples were immersed in phosphate-buffered saline solution at 50 °C for 112 days and mass loss, molecular weight, thermal properties, degree of crystallinity, FTIR and Raman spectra, tensile elastic modulus, yield stress and failure stress/strain were evaluated at consecutive time points. Samples showed a consistent reduction in molecular weight and melting temperature, a consistent increase in percent crystallinity and limited changes in glass transition temperature and mass loss. At day 49, a drastic reduction in tensile failure strain was observed, despite the fact that elastic modulus, yield and tensile strength of samples were maintained. Brittleness increase was followed by rapid increase in degradation rate. Beyond day 70, samples became too brittle to test indicating substantial deterioration of their load-bearing capacity. This study also presents a computational micromechanics framework that demonstrates that the elastic modulus of a semi-crystalline polymer undergoing degradation can be maintained, despite a reducing molecular weight through compensatory increases in percent crystallinity. This study presents novel insight into the relationship between physical properties and mechanical performance of medical-grade PLLA during degradation and could have important implications for design and development of bioresorbable stents for vascular applications.

Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

Glass fibre reinforced cement (GFRC) is a composite material with great ductility but it undergoes severe strength and ductility degradation with ageing. Calcium sulfoaluminate (CSA) cement is low carbon cement, and more importantly, it exhibits great potential to produce more ductile and durable GFRC. This study focuses on mechanical performance, e.g., compressive strength, stress‐strain curve, and freeze‐thaw resistance of CSA/GFRC as well as its microstructural characteristics under low temperatures. XRD was applied to investigate the hydration mechanism of CSA cement under −5°C, 0°C, and 5°C. It was found out that low‐temperature environments have very little effect on the type of hydration products, and the main hydration product of hydrated CSA cement cured under low temperatures is ettringite. Moreover, low‐curing temperatures have an adverse effect on the compressive strength developments of CSA/GFRC but the strength difference compared with that under 20°C reduces gradually with increasing curing ages. In terms of bending performance, both ultimate tensile strength and ultimate strain value indicate considerable degradation with ageing under low temperatures after 14 d. The ultimate strain value reduces to 0.34% at −5°C, 0.39% at 0°C, and 0.44% at 5°C compared with 0.51% for that cured at 20°C for 28 d. The tensile strength of samples cured at −5°C for 28 d is only 15.2 MPa, taking up only 40% of that under 20°C. CSA/GFRC also demonstrated great capability in the antifreeze‐thaw performance, and the corresponding strength remains 95.9%, 94.7%, 94.2%, and 94.3%, respectively, for that cured under 20°C, 5°C, 0°C, and −5°C after 50 freeze‐thaw cycles. Microstructural studies reveal that densification of the interfilamentary space with intermixtures of C‐A‐S‐H and ettringite is the main reason that causes the degradation of CSA/GFRC, which may result in loss on flexibility when forces are applied, therefore reducing the post‐peak toughness to some extent.

Effect of Water Absorption on the Tensile Characteristics of Natural/ Synthetic Fabrics Reinforced Hybrid Composites

The effect of water absorption and swelling thickness on the tensile properties of flax/sisal/carbon/glass fabrics reinforced by unsaturated polyester-based hybrid composites was evaluated. Hybrid composites reinforced with different natural and synthetic fiber configurations have been processed using the Hand lay-up (HLU) technique. Water absorption test was carried out by immersing specimens in distilled water for different lengths of time, up to 1344 hours, and showed slight enhancement of water absorption for fibers configuration [C/C/C/C/C/C] up to 1.45%, but great enhancement of water absorption for fiber configuration [S/S/S/S/S/S] up to 14%. The tensile strength of samples before and after immersion in distilled water was evaluated. This result showed that the tensile strength of fibers configuration [C/C/F/F/C/C] is approaching fibers configuration [C/C/C/C/C/C] at dry condition. Fractured cross-section morphology of composites was investigated using scanning electron microscopy (SEM) to evaluate the fibers/matrix interface before and after hydro aging. The reduction in tensile strength due to water penetrating is slight for hybrid composite with synthetic fibers at the outer layer, but huge for hybrid composite with natural fibers at outer layer.

Fracture behavior of single-crystal silicon microstructure coated with stepwise bias-graded a-C:H film

Fracture behavior in the tensile testing of a single-crystal silicon (SCS) microstructure with a stepwise bias-graded hydrogenated amorphous carbon (a-C:H) coating was investigated to explore the fracture mechanism of the coating−substrate system. All sides of the SCS microstructure (120 × 4 × 5 μm3) were coated uniformly with a 300-nm-thick a-C:H film deposited by plasma enhanced chemical vapor deposition (PECVD). In this research, four different bias conditions with stepwise changes were applied during deposition to make the hard−compliant or compliant−hard gradient in the coating film. The microstructure, chemical composition, and mechanical properties were evaluated by scanning electron microscopy, Raman spectroscopy, nanoindentation, and surface profilometry. A tensile test showed a significant increase in tensile strength for samples with a multilayer gradient coating, which was 6.3–56.6% higher than that of the SCS sample, and a similar increase was observed for fracture toughness. The fracture mechanisms were elaborated by analyzing the chemical composition and stress intensity factor. The results indicate that the tensile behavior was strongly affected by the surface energy and stress state of the a-C:H coating.

Preparation of degradable vegetable oil-based waterborne polyurethane with tunable mechanical and thermal properties

In this study, the fully degradable soybean oil-based waterborne polyurethanes (SWPU) were prepared, and the mechanical properties, thermal properties and hydrophilicity of SWPU films were adjusted by changing the R value. First, soybean oil-based polyol was fabricated via epoxy soybean oil and ricinoleic acid in the absence of solvent and catalyst. Then, the resulting polyol was mixed with isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), trimethylamine (TEA) and ethylenediamine (EDA) to synthesize polyurethane emulsion with different R value (the molar ration of –NCO/–OH). The result showed that as the R value increased, the tensile strength of SWPU film was increased from 10.02 to 27.32 MPa, the initial decomposition temperature of polyurethane films was improved from 201 ℃ to 246 ℃, the Tg,h was increased from 68 to 130 ℃ and the water contact angle of SWPU films were enhanced from 82.4° to 95.5°. It can be explained that the degree of crosslinking of the polyurethane elastomer was improved and the interaction of the molecular chains became stronger with larger R value. Also, all SWPU films were placed in the 3 wt% sodium hydroxide solution at 45 ℃ to test the degradability, and the weight loss of samples at different degradation time were calculated, respectively. Finally, the morphology, FT-IR and tensile strength of samples was observed before and after degradation, and a possible mechanism of degradation was studied. The technique reported here demonstrated that it was possible to develop the degradable materials.

The Effect of Incorporating Silica Stone Waste on the Mechanical Properties of Sustainable Concretes.

Incorporating various industrial waste materials into concrete has recently gained attention for sustainable construction. This paper, for the first time, studies the effects of silica stone waste (SSW) powder on concrete. The cement of concrete was replaced with 5, 10, 15, and 20% of the SSW powder. The mechanical properties of concrete, such as compressive and tensile strength, were studied. Furthermore, the microstructure of concrete was studied by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy analysis (EDX), Fourier transformed infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) tests. Compressive and tensile strength of samples with 5% SSW powder was improved up to 18.8% and 10.46%, respectively. As can be observed in the SEM images, a reduced number of pores and higher density in the matrix can explain the better compressive strength of samples with 5% SSW powder.

Mechanical Properties of Martensitic Stainless Steel (AISI420) Subjected to Conventional and Cryogenic Treatments

Martensitic Stainless Steel (AISI420) MSS are vastly used because of their properties conventional which mix good mechanical and corrosion resistance. Cryogenic up to -196°C for different soaking time and heat treatments at (1000,500,200°C) for 15 minutes is one of the ways that used to enhance mechanical properties of these steels by means transformation of retained austenite, deformation regarding martensite then carbide refinement. the result showed an increase in tensile strength of samples that were treated cryogenically and tempered at 500°C was 933 (MPa) compared to samples that just treated conventionally in austenitizing and tempering at the same temperature that was 880 (MPa). The hardness values increased considerably to 414HV and 321 HV for the specimen that tempered at 200°C and 500°C respectively, precipitation of small carbides was observed that this is responsible for the improvement in the mechanical properties of the material.

Fabrication and Characterization of Electrospun Scaffold Based on Polycaprolactone-Aloe vera and Polyvinyl Alcohol for Skin Tissue Engineering

In the present work, the biodegradable nanofibrous scaffolds containing poly(caprolactone) (PCL), poly(vinyl alcohol) (PVA) and aloe vera (AV), through two nozzles electrospinning method, were prepared and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle measurement and mechanical analysis. The biocompatibility and cell growth were evaluated using MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Adding poly(vinyl alcohol) (PVA) and poly(caprolactone) (PCL) boosted the electrospinability of aloe vera (AV) solution and mechanical features of the scaffolds. According to the Scanning electron microscopy (SEM) results, uniform PVA/AV-PCL nanofibers were fabricated with the average diameter about 119±11.78 nm. Fourier-transform infrared spectroscopy) FTIR (confirmed the presence of functional groups of scaffolds. The results of the contact angle showed that by adding aloe vera, the hydrophilicity increased. The results showed that the tensile strength of samples with 6 mg/ml AV, reached to 2.02 MPa. MTT results showed that all samples had a cell viability of over 80 %. It can be concluded that nanofibrous scaffolds with concentration of 6 mg/ml, distance between syringe tip/collector of 15 cm, feed rate of 3 ml/h and applied voltage of 12 kV, have appropriate properties for skin tissue engineering by stimulating the fibroblast cells and therefore accelerating the regeneration processes of damaged skin.

Effects on the evolution of microstructure and properties of low-silicon cast aluminum alloys in service

ABSTRACT The microstructure evolution and property change of four kinds of low silicon cast aluminum alloy exposed to heat for 0–50 h at 200°C were studied by means of Brinell hardness test, tensile property test, friction and wear property test and XRD analysis. The results show that with increasing thermal exposure time, the tensile strength of each group of samples decreased and the amount of wear increased. The tensile strength of samples with more Si content decreased slowly. When the time increased to 50 h, the increase of wear loss was the largest. The hardness of samples after thermal exposure increases compared with that before thermal exposure. The residual stress of (311) diffraction crystal surface of AlSi3.5Mg0.66 under different thermal exposure time was measured. The type of residual stress changed from residual tensile stress to residual compressive stress after thermal exposure. There is an abnormal phenomenon that the hardness of the sample increased and the amount of wear increased, and it is evident that the distribution of residual stress was inhomogeneous after thermal exposure. It is found that with increasing thermal exposure time to 50 h, the average lattice distortion ε of the low-index crystal plane and the high-index crystal plane in the aluminum alloys gradually increased.

Technology of Exposed Rock Surface Insulation against the Influence of Mine Atmosphere

The authors discuss the problem connected with insulation of exposed rock surface areas against the aggressive influence of mine atmosphere and rock falls during mining. The lab-scale tests determine the moisture effect on the strength of rocks in the Orlov Ore Field. The tensile strength of samples of isolation membrane as well as their adhesion to rocks and shotcrete is assessed. The technology of preparation and application of polymer membrane insulation layer on the surface of differently damaged areas on the roof and sidewalls in stopes is justified for the Orlov Mine.

Effect of particulate fillers on mechanical, metallurgical and abrasive behavior of tungsten reinforced HDPE composites: A Taguchi approach

Tungsten reinforced High-Density polyethylene (HDPE) composites are developed by melt compounding in twin-screw extruder and samples containing 1, 3, 5 and 7 wt% of tungsten particles are formed by injection molding. Investigations on Mechanical, Metallurgical and tribological behavior of developed composites with varying filler compositions are presented. Tensile strength of sample containing 1 wt% of tungsten filler was found to be high. X-ray diffraction (XRD) analysis shows that the crystallinity of the HDPE matrix is affected by the addition of Tungsten fillers. To access the wear behavior of the composites, two-body abrasive wear test was conducted in Pin-on-disc wear test apparatus with Filler content (A), Load (B) followed by sliding distance (C) as parameters which are varied at four levels and coefficient of friction (COF), Specific Wear Rate ( W S )are the responses. The experiment designed to optimize the number of experimental runs is based on Taguchi’s (L 16 ) orthogonal array. Graph of main effects plot shows A 4 B 4 C 4 as the desired sequence for minimum W S and COF. Through variance analysis, the load was found to be the dominant factor influencing the wear characteristics followed by the content of filler and sliding distance. SEM analysis of worn samples was done to study the worn surface morphology.

Numerical Simulation of the Effect of Double Hole Dip Angle on Tensile Strength and Failure Characteristics of Red Sandstone

In order to study the effect of dip angle on the tensile strength and failure characteristics of red sandstone, based on the results of the Brazilian splitting test for indoor double-hole red sandstone samples, using the PFC2D particle flow numerical simulation technique to simulate the Brazilian splitting test of precast double-hole red sandstone samples, the effect of dip angle on the tensile strength and failure characteristics of red sandstone samples is studied, further, the evolution characteristics of the surface stress field of the double-hole red sandstone specimen during the tension process are analyzed, and the failure mechanism of the red sandstone in the double-hole red sandstone is revealed. The results show: (1) Increasing the inclination angle of the double hole from 0°to 60°the tensile strength of the sample is stepped down, the maximum drop is when the double hole is inclined at 45°;(2)When the double hole inclination angle is 0°-30°, the crack extends through a single hole; when the double hole inclination angle is 45°-60°, the crack propagates through the double hole.(3)The tensile stress concentration zone near the double hole is the main factor affecting the tensile strength and crack propagation of the sample: ① When the tensile stress concentration region at the edge of the hole A and the hole B is not penetrated (0°, 15°, 30°), the tensile strength of the sample is large, when the crack propagates, only a single hole is penetrated; ② When the tensile stress concentration region at the edge of the hole A and the hole B is penetrated (45°, 60°), the tensile strength of the sample is greatly reduced, the double hole is penetrated when the crack propagates.

Optimization of mechanical properties of in situ polymerized poly(methyl methacrylate)/alumina nanoparticles nanocomposites using Taguchi approach

Alumina nanoparticles are among important metal oxides with specific properties but chemically incompatible with an organic matrix such as poly(methyl methacrylate) (PMMA). In this research, in situ polymerization of methyl methacrylate was performed on alumina nanoparticles to improve the interaction of the nanoparticles and PMMA. These modified nanoparticles were applied as effective additives with appropriate dispersion in the polymer matrix. Different samples were produced using an injection molding process in order to compare the mechanical properties of nanocomposites containing modified and unmodified nanoparticles. X-ray diffraction and scanning electron microscope tests were performed to investigate the effect of modification process on the dispersion quality of nanoparticles into the PMMA matrix. The results indicated that the modified alumina nanoparticles had a better dispersion and interaction in comparison with unmodified alumina nanoparticles due to the modification procedure. Taguchi approach was implemented for the design of experiments and optimization of input parameters. The MCDM methods were also used to select the best experiment according to the different material and process parameters. Impact and tensile strength of samples with 2 wt% of modified alumina nanoparticles were 22.5% and 21.5% better than a sample with the same unmodified alumina nanoparticles content, respectively.