Mechanical Properties of Developed Corncob-Urea Particles Hybrid Reinforced Polyester-Based Composites

This study investigates the development of hybrid-reinforced polyester composites using corncob and urea particles as reinforcement for sustainable applications. Composites were fabricated by the stir casting method with varying weight fractions of corncob and urea. The mechanical and physical properties of the developed composites were evaluated, while fracture surface morphology was examined using scanning electron microscopy (SEM). The burning rates of the samples were investigated to evaluate their flame-retardant potential. The results demonstrate that incorporating corncob and urea effectively enhances stiffness-related mechanical properties, including tensile and flexural moduli and hardness. Composite containing 12 wt% urea and 3 wt% corncob exhibited the highest flexural moduli and hardness with an improvement of 122% and 45%, respectively. Composite with 3 wt% corncob and 18 wt% urea has the highest flexural strength with an increase of 44%, composite with 9 wt% corncob and 18 wt% urea has the highest tensile modulus with an improvement of 22%. In addition, it was found that the presence of corncob and urea reduced burning rates, with the sample containing 15 wt% corncob and 18 wt% urea exhibiting the lowest burning rate, indicating better flame-retardant potential. Thus, the findings indicate that corncob–urea hybrid reinforcement offers a promising, sustainable approach to enhancing the mechanical stiffness and reducing the burning rate of polyester composites. These materials have potential for use in applications requiring improved durability and low burning rate potentials while reducing reliance on conventional synthetic additives.