Almond-Walnut Shell Hybrid Composite: Optimization of Composition Using Mixture Design

The current work presents the mixture design method to optimize the composition of almond-walnut shell hybrid composite. In this regard, the different numerical models were developed and realized that the quadratic & cubic are best suitable to set up a correlation between input and response parameters. The numerical equalizations and experiential outcomes authenticate that the inclusion of shell particles (almond and walnut) enhanced the thermo-mechanical and biodegradation characteristics of the polyester resin. Hybridization yielded a positive effect and exhibited better performance than the single filler strengthened ones. The validation test results revealed that the mixture design is an effective optimization tool to develop a high-performance hybrid composite. The optimal specifications as almond shell proportion: 19.6%, walnut filler: 20.4%, polyester resin: 60%, tensile strength: 44.09 MPa, flexural strength: 58.68 MPa, impact strength: 5.60 kJ/m², Young's modulus: 1.57 GPa, flexural modulus: 1.68 GPa, moisture absorption: 5.26%, thermal decomposition temperature: 390.76 °C, and biodegradation: 51.12%.