https://ejosat.com.tr/?mod=sayi_detay&sayi_id=4017 European Journal of Science and Technology tr 2025-12-01 https://ejosat.com.tr/?mod=makale_tr_ozet&makale_id=94076 https://ejosat.com.tr/?mod=makale_tr_ozet&makale_id=94076 Muttalip Ergun Turgay Copper doped and undoped manganese sulfide (MnS) thin films were deposited by Spray Pyrolysis Technique at 390 oC using copper chloride (CuCl2) as an additive source using 0.1 g, 0.3 g and 0.5 g CuCl2. The Mn:S ratios were adjusted to be equal and 1:1 and the spraying process was carried out completely in atmospheric environment. The optical properties of the obtained MnS thin film samples were investigated by using Shimadzu-1800 Model UV/VIS spectrophotometer. It is seen that the band gap energy range of copper-doped and undoped MnS thin films varies between 2.95 and 3.27 eV. The effects of these observed changes and the amount of copper chloride on the optical properties of MnS thin films were investigated. 2025-12-01 https://ejosat.com.tr/?mod=makale_tr_ozet&makale_id=94078 https://ejosat.com.tr/?mod=makale_tr_ozet&makale_id=94078 Ömer Şengül ,Hasan YILMAZ This study explores the development and characterization of sustainable polymer composites reinforced with coconut shell powder (CSP), an agricultural by-product, incorporated into a recycled polypropylene (rPP) matrix. The composites were fabricated via homogeneous blending using a twin-screw extruder followed by injection molding, with CSP loadings of 2%, 5%, 8%, 10%, 12.5%, 15%, 18%, and 20% by weight. The mechanical and physical properties, including tensile strength, Izod impact strength, hardness, and density, were systematically evaluated to determine the reinforcing effect of CSP as a natural filler within the recycled matrix. The results revealed a significant improvement in mechanical performance up to 15 wt.% CSP, where the tensile strength reached 25.60 MPa, yield strength increased to 20.99 MPa, and the elastic modulus nearly doubled to 1213.72 MPa compared to neat rPP. The impact strength improved to 5.98 kJ/m², Shore-D hardness increased from 68 to 71, and density rose from 0.890 g/cm³ to 0.930 g/cm³. Beyond this threshold, excessive filler loading led to particle agglomeration and reduced matrix cohesion. These findings indicate that CSP–rPP composites offer a promising balance between strength, stiffness, and weight, making them suitable for non-structural and semi-structural applications in marine auxiliary machinery systems, such as pump housings, valve components, insulation covers, and pipe supports, where corrosion resistance and low density are critical. Furthermore, the utilization of recycled and bio-based constituents contributes to sustainable shipbuilding practices, aligning with green ship design principles and international maritime environmental standards. This work highlights the potential of agricultural waste valorization in producing eco-efficient materials tailored for marine engineering applications. 2025-12-01