Comparative mechanical properties of polyester and polyethylene composites reinforced with sunflower seed hull fibers

This study investigates the development and characterization of novel composite materials using sunflower seed hull fibers as reinforcement in polyester and polyethylene matrices. The fibers were extracted via alkaline treatment (10% NaOH) and mechanical separation. Composites were fabricated with various fiber mass fractions (0-40% for polyester and 0-22% for polyethylene) using a compression molding technique. Mechanical properties were evaluated through tensile, flexural, impact, and compression tests according to ASTM standards. Results showed significant improvements in the mechanical properties of polyester-based composites. The polyester/sunflower seed fiber composite exhibited a 50% increase in tensile strength at 40% fiber mass fraction, while flexural strength improved by 63%, reaching 70.52 MPa. Impact strength was 3.3 times greater than that of neat polyester resin, and compressive strength reached 143.5 MPa. Polyethylene-based composites showed more modest improvements, with a 12% increase in tensile strength and a 35% improvement in flexural strength at 22% fiber content, although impact strength decreased with increasing fiber content. This study demonstrates the potential of sunflower seed hull fibers as an effective, sustainable reinforcement material for polymer composites, particularly in polyester-based systems. These novel composites could be viable alternatives for applications requiring enhanced mechanical properties while maintaining environmental sustainability.