The present work deals with the effective utilization of almond shell bio-waste fillers in the production of vinyl ester polymer composites. The almond shell particle surface was chemically modified by alkaline treatment. The almond shell particles with varying weight percentages of 5%-30% were used to prepare the vinyl ester polymer composite. The experimental results show that a 25% addition of alkaline-treated almond shell particles significantly improved the mechanical properties of the composite when compared to pure vinyl ester and untreated almond-filled composite samples. The highest tensile, flexural, impact strength, and Shore D hardness of the 25% alkaline-treated almond shell composite were 54, 142 MPa, 31, and 79 kJ/m 2 , respectively. This was due to the alkaline treatment of almond shell particles, which improved the interfacial adhesion between the vinyl ester matrix and almond particles. The heat deflection temperature of the 25% alkaline treated almond shell particlefilled vinyl ester matrix composite was 72 C. The thermal insulating characteristics of alkali-treated almond shells were improved due to the reduction of quickly thermal degradable materials such as hemicelluloses and lignin, as indicated by Fourier transform infrared spectroscopic data, and more exposure of minerals to the surface, as confirmed by energy dispersive X-ray analysis. The addition of alkaline-treated almond shell particles improves the characteristics of the vinyl ester matrix and allows the development of biocomposites. K E Y W O R D S alkaline treatment, almond shell, bio-composite, mechanical properties, thermal deflection, vinyl ester
Adding alloying elements like copper (Cu) and zirconium (Zr) to binary NiTi shape memory alloys (NiTiCuZr SMA) raises the martensitic transition temperatures and functional fatigue properties while maintaining high corrosion and wear resistance. Therefore, it is essential to make high-precision SMA components with less damage to be machined into various complex shapes, sizes, and surface topographies to meet the needs of several engineering applications. In this research work, advanced machining processes like wire electrical discharge machining (WEDM) and fiber laser machining were employed to machine NiTiCuZr SMA and study their processing parameters' effects on the surface roughness, topography changes, and surface hardness. 3D surface topography and surface roughness on the machined surfaces were evaluated through contact and non-contact measurement techniques. The differential scanning calorimetry (DSC) test was conducted on the NiTiCuZr SMA before and after machining to confirm changes in the shape memory properties. When both processes were used at high energy levels, the formation of the resolidified layer and surface defects were more pronounced, increasing surface roughness. DSC curves for heating and cooling profiles show similar transformation temperatures for WEDM and laser machined NiTiCuZr SMA. On comparing two different machining processes, the WEDM process resulted in the Ra (µm) being 28.2% lower, the surface topography was smooth, and the microhardness was 11.9% lower than the samples machined using laser machining. This shows that machining of NiTiCuZr SMA using WEDM gives a better surface finish, reaching a fair decision that WEDM is a better alternative to laser machining.
The selection of fibers and their stacking sequence, which affect structural integrity and functional properties, are critical parts of polymer composite design. In this work, the influence of various stacking sequences made of basalt and flax fiber layers on the mechanical, thermal, and dynamic mechanical analyses of vinyl ester polymer composites was investigated. The stacking sequence designed by alternate basalt and flax layers showed higher tensile and flexural strengths, with basalt layers in the outer positions. The high‐strength basalt fiber retains considerable stress, particularly in the outer layer, reducing stress transfer to the remaining core layers. The basalt and flax fiber alternative layered sequence with outer basalt layers shows a slightly lower thermal degradation temperature (467°C) than the only basalt layered sequence composite (474°C). Because of the high thermal resistance of the outer basalt layers, heat flow to the next fiber layers is reduced. The dynamic mechanical analysis reveals that the polymer composite intertwined with only basalt fiber was found to have a higher storage modulus. On the other hand, the outer basalt layers intertwined with the core flax layers composite showed a 122% higher damping value than the stacking sequence made of only basalt fiber due to the porous structure of flax fibers dissipating more vibration energy.
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