Utilization of eggshell, pomegranate, and mandarin peels as biofillers in butadiene nitrile rubber (NBR) composites

This study explores the use of agricultural waste-derived biofillers-eggshell powder, pomegranate peel, and mandarin peel-as sustainable reinforcements in butadiene nitrile rubber (BNR) composites.Incorporating biofillers into polymer matrices offers an environmentally friendly alternative to conventional petroleumbased fillers, supporting the development of green materials.Biofillers were airdried, finely ground, and characterized for morphology, chemical composition, and thermal stability.BNR composites containing varying biofiller loadings (0-10 phr) were prepared and evaluated through mechanical, thermal, and physicochemical analyses.Results revealed that biofiller incorporation significantly affected composite properties.Mandarin peel exhibited the highest reinforcement efficiency, enhancing tensile strength by 50%, hardness by 33%, and reducing swelling in toluene by 32% at an optimal 6 phr loading.These improvements were attributed to its high lignin and pectin content, which increased polymer-filler interaction and crosslink density.Pomegranate peel also showed strong reinforcement capabilities, increasing hardness by 15 Shore A units and crosslink density by 40%, making it suitable for rigid and chemically resistant applications.In contrast, eggshell powder demonstrated weaker interfacial adhesion due to its inorganic nature, resulting in higher swelling and lower mechanical performance.The study underscores the importance of biofiller selection in achieving desired mechanical and solvent resistance properties in BNR composites.Mandarin peel-filled BNR composites displayed superior resistance in solvents like benzene, CCl4, and toluene, indicating their potential for use in harsh environments.Overall, the findings highlight biofillers as promising, eco-friendly alternatives to synthetic reinforcements in rubber composites