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Due to the inherent high surface energy and the multifaceted interaction between them and the matrix interface, metal nanoparticles tend to coalesce in the absence of repulsive forces provided by a capping agent. It is therefore imperative to provide a support system that will moderate the spatial behaviour of the particles to prevent the formation of bulk particles and eventually deteriorate in quality. This paper reports the influence of weight fraction on the average crystallite size of Al2O3 introduced onto formulated ZnO groundnut shell activated carbon (GSAC) supported composites. Al2O3 was synthesised using the sol-gel technique with aluminium trichloride as precursor salt. The surface morphology and average particle size of synthesised Al2O3 were determined using scanning electron microscopy (SEM) and transmission electron microscope (TEM), respectively. Al2O3 was introduced onto formulated GSAC/ZnO mixture at varying weight percentages (75:25, 50:50 and 25:75) to produce GSAC-ZnO/Al2O3 composites. The resulting composites were then characterised using X-ray diffraction (XRD). Relying on lattice parameters such as diffraction peaks and full width at half maximum (FWHM) obtained from the X-ray powder diffraction, the effects of weight fraction on the average crystallite size of ZnO/Al2O3 supported GSAC composites were determined using the Scherrer equation. The result obtained showed an increase in average crystallite size with the increase in amount of Al2O3 introduced onto the formulated GSAC/ZnO composite, but declined with further addition of Al2O3. The GSAC-ZnO/ Al2O3 composite with a 75:25 weight fraction was found to have the smallest average crystallite size of 52.25 nm. The results suggest that the stabilisation influence of GSAC on ZnO and Al2O3 is reduced with an increase in the amount of Al2O3 and the tendency for agglomeration of ZnO and Al2O3 ions may have been weakened with the addition of more Al2O3, resulting in a decrease in crystallite size.

Abstract

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Low-carbon steel (LCS) is applied in numerous engineering applications, such as construction, automobile manufacturing, and product and component manufacturing, due to its unique mechanical properties. They are readily available, hence are very cost-effective when considered in any application. However, they are usually affected by corrosion when exposed to chloride-induced media, due to the penetration of chloride ions. Biopolymer coatings electrodeposited on the surface of metals have been shown to restrict the penetration of chloride ions into the metallic substrate, thereby slowing down the corrosion rate. This study was aimed towards electrodepositing Zinc-magnesium oxide-cellulose nano-particle coatings (Zn-xMnO-xCn) on LCS for improved corrosion resistance in sodium chloride media. The gravimetric technique was used to determine the corrosion rates of the deposited coatings (samples). The samples’ morphology and composition were determined via optical microscopy and scanning electron microscopy, equipped with an energy-dispersive spectrometer. Corrosion data from the results showed that all the coatings recorded lower corrosion rate values than that of the LCS substrate, whose value was 5.0025 mm/y. Among the coatings, sample M10 (Zn-20gMgO-20gCn) had the least corrosion rate value of 0.2582 mm/y, corresponding to a coating protection efficiency of 95% on the LCS. The highest corrosion rate value was recorded by M7 (Zn-20gMgO-5gCn) with a value of 2.2236 mm/y corresponding to a protection efficiency of 56% on the LCS. The coating morphologies revealed uniformly distributed and fine grains on the LCS’ surface. The study showed that the Zn-xMnO-xCn coatings were able to form protective barriers on the substrate in the sodium chloride media.

Abstract

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Bamboo fibres were treated with varying conditions of soaking time, accelerator/catalyst ratio and NaOH treatment concentration. These parameters play a major role in determining the performance properties of the developed polyester composite for structural applications. The reinforced 10 – 40 wt% bamboo fibre–polyester composites were fabricated using the hand layup technique and the mechanical properties (tensile, hardness, impact and flexural strength) were evaluated using a universal testing machine and Charpy impact tester. Due to the varying conditions of the parameters, the Taguchi L16 orthogonal array was employed to design the experiment. Microstructural analysis was conducted using a scanning electron microscope to study the surface morphology of the composite. The mechanical properties of the developed bamboo fibre reinforced polyester composite were evaluated considering the bamboo fibre (BF), soaking time (ST), accelerator/catalyst ratio (ACR) and NaOH treatment concentration. The study revealed that wt% of the bamboo fibre improves the properties at 30 - 40 wt% as 30 wt% attained the optimum for hardness (121.16 Hv) and flexural strength (93.99 MPa) while 40 wt% for tensile (78.53 MPa) and impact strength (4.85 KJ/m2). Soak time enhanced the properties within 2 – 3 hrs with an optimum of 2 hrs for tensile strength (77.68 MPa) and 3 hrs for impact (5.52 kJ/m2) and flexural strength (89.04 MPa). The ratio of accelerator/catalyst displayed optimum at 1.2 mix for hardness (119.54 Hv), flexural (93.61 MPa) and tensile strength (70.34 MPa). High volume of accelerator to catalyst mix leads to brittleness, debonding of the polymer composite. Lower NaOH treatment concentration achieved the optimum for the mechanical properties. However, higher NaOH concentration degrades the fibres and reduces their strength and stiffness, ultimately decreasing the composite properties. This study provides the relationship amongst the process parameters and their influence on the mechanical properties of bamboo fibre reinforced polyester composite for structural applications.

Abstract

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The development of a lightweight military helmet using granite particulate (GTP) reinforced recycled low-density polyethylene (RLDPE) was studied in an attempt to produce a light helmet with high strength and cost-effective material for military applications. This study utilised the abundant presence of granite in the ecosystem. The granite stone was washed using distilled water and detergent and sun dried, then ball milled for 72 hours. The process was followed by compounding the granite powder with recycled low-density polyethylene (pure water sachet) and compatibiliser (propylene glycol) in a two-roll mill compounder at a temperature of 150℃ for 5 minutes. Six samples were produced by varying the composition of granite from 0 to 50 wt. % (at regular interval of 10%), one of the six samples is a control sample and it was used to compare the other samples. The samples were characterised using SEM and then tested for hardness, tensile, flexural and impact strengths, and density. The SEM images showed dispersion of the GTP. Additionally, mechanical properties improved with the addition of the filler while density depreciated mildly, especially at 10% loading.

Abstract

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The reuse of waste glass in concrete production is an attractive option for achieving waste reduction and preserving natural resources from further depletion, thereby protecting the environment and promoting sustainability. This present study examined the variation in the strength properties of concrete using waste glass aggregate (WGA) as a partial replacement for different coarse aggregate gradings. Three-quarter-inch (20 mm) and one-inch (25 mm) coarse aggregates were partially replaced with WGA of the respective sizes in different percentages: 0 %, 10 %, 20 % and 30 %. Physical properties such as specific gravity, bulk density, slump, and workability of fresh concrete and strength properties such as compressive strength and tensile strength of hardened concrete of grade M25, mix ratio 1:1:2 were tested after 7, 14, 28, 56 and 90 days. The results of the physical properties revealed that the WGA exhibited a lower specific gravity value of 2.70, bulk density of 1364 kg/m3, and moisture content of 0 % as compared to granite, with a specific gravity value of 2.74, bulk density of 1660 kg/m3, and moisture content of 0.01 %. The compressive strength results of both 20 mm and 25 mm WGA increase as the curing age of the concrete increases progressively from 7 days up to 90 days. At 7 and 90 days the compressive strength results of 20 mm aggregate of the control mix concrete were 30.05 N/mm2 and 42.60 N/mm2 respectively while that of 20 mm 30 % WGA partial replacement were 32.14 N/mm2 and 45.70 N/mm2 respectively, and for 25 mm aggregate control mix concrete were 29.74 N/mm2 and 49.80 N/mm2 respectively, while that of 25 mm, 30 % WGA partial replacement were 28.71 N/mm2 and 45.50 N/mm2 respectively. The tensile strength for all the ages reached the optimum value at 10 % partial replacement WGA for both 20 mm and 25 mm. At 28 days, the tensile strength result of 20 mm aggregate of the control mix concrete was 2.86 N/mm2, while 20 mm 10 % WGA replacement was 2.90 N/mm2, and for 25 mm aggregate control mix concrete, the tensile strength result was 3.11 N/mm2, while that of 25 mm WGA was 2.55 N/mm2. The results of the strength properties showed that the concrete grade M25 adopted was suitable for the WGA partial replacement, as the compressive strength results for all ages did not fall below 25 N/mm2.

Abstract

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This study investigates the structural properties of concrete when coconut shell is used as a partial replacement for coarse aggregate. The objective is to evaluate the effect of this replacement on workability, compressive strength, and flexural strength of concrete. Mix designs were prepared by replacing conventional coarse aggregate with coconut shell at varying percentages of 0%, 10%, 20%, and 30% by weight. Standard concrete tests were conducted, including slump tests for workability, compressive strength tests at 7, 14, and 28 days, and flexural strength tests at 28 days. The results revealed that slump values decreased with an increase in coconut shell content, indicating reduced workability. Compressive and flexural strengths also decreased with higher percentages of coconut shell; however, concrete with a 10% replacement showed acceptable strength for light structural applications. The study concludes that coconut shells can be used effectively as a partial replacement for coarse aggregate in concrete for non-load-bearing and low-cost construction, contributing to sustainable waste management and reduction of construction costs.

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This study examines the influence of nanoclay loading on the hardness properties of epoxy composites. Nanocomposites were fabricated using varying weight ercentages of nanoclay and epoxy via the hand layup method with an open mould. Mechanical characterisation was carried out using a Rockwell hardness tester, while the dispersion and morphology of nanoclay particles within the epoxy matrix were analysed using Scanning Electron Microscopy (SEM). The composite containing 4 wt.% nanoclay (nanoclay-to-epoxy ratio of 4:96) exhibited the highest hardness value of 109.60 HRA, representing a 65% improvement over the control sample (neat epoxy). The results demonstrate that the incorporation of nanoclay significantly enhances the hardness of epoxy, with hardness values increasing proportionally with nanoclay content up to an optimum level. Beyond this saturation point, a decline in hardness was observed, attributed to particle agglomeration and poor interfacial adhesion between the nanoclay and the epoxy matrix. Overall, the findings establish nanoclay as an effective reinforcement material for epoxy polymers where improved hardness is required.

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This study investigates the physical and mechanical properties of low-density polyethylene (LDPE)/doum fibre composites with varying filler loadings. Six composite samples were fabricated using a metal mould of dimensions 120 × 120 × 3 mm, with LDPE and doum fibre mixed in ratios of 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50. Processing was carried out at 120 °C for 5–10 minutes. The prepared samples were subjected to tensile tests to evaluate tensile strength, strain, percentage elongation at break, Young’s modulus, and density. Results revealed that the neat LDPE sample (100:0) exhibited the highest tensile strength, strain, and longation at break, whereas the 50:50 LDPE/doum fibre composite recorded the highest Young’s modulus. The findings indicate that increasing doum fibre content, accompanied by a reduction in LDPE, decreases tensile strength, strain, and elongation at break, while enhancing the stiffness of the composite as reflected in the increased Young’s modulus.