Exploring the mechanical and thermal characteristics of polypropylene composites with recycled polyester waste as sustainable reinforcement for enhanced protection in safety helmets head band

The mechanical and thermal characteristics of Recycled Polyester Waste (RPW) reinforced in a polypropylene (PP) matrix were investigated to evaluate their feasibility for producing safety helmet components. Five samples with varying PP and RPW ratio weight fractions were prepared (Sample A:90/10, Sample B:80/20, Sample C:70/30, Sample D:60/40, and Sample E:50/50) and compounded by twin-screw extruder and developed using an injection molding machine. The density, hardness, tensile, and flexural properties of all samples, such as stress, strain, modulus, impact resistance, and Vicat softening temperature, were measured and compared. The findings indicated an increase in density as the RPW content increased, ranging from 0.92 g/cm³ for sample A to 1.23 g/cm³ for sample E. The hardness also increased from 69 Shore D in Sample A 87 Shore D in sample D. The tensile stress and modulus increased from 25.5 MPa to 543 MPa, respectively, for sample A to 27.6 MPa and 827 MPa, respectively, for sample D. The flexural strength and flexural modulus increased from 31.2 MPa to 775 MPa, respectively, for sample A to 34.3 MPa and 1250 MPa, respectively, for sample D. The impact resistance increased as the RPW content increased, ranging from 555 J/m for Sample A 656 J/m for sample D. The Vicat softening temperature increased from 73°C for Sample A to 91°C for Sample E. These findings indicate that RPW has the potential to improve the thermal and mechanical properties of PP, rendering it a sustainable and plausible reinforcement option for head band components of safety helmets.