Harnessing an Invasive Species: Pennisetum setaceum Fiber Reinforcement in Polymer Composites for Sustainable Materials

Abstract

This study investigates the valorization of waste from Pennisetum setaceum eradication and control campaigns as a reinforcement for composite materials. This approach promotes more sustainable material and improved waste management. The fiber was incorporated into both high-density polyethylene (HDPE) and polylactic acid (PLA) matrices. Various fiber treatments—alkaline, acetic acid, silane, and combined alkaline-silane—were examined for their effects on composite properties. The manufacturing process had two stages: first, the fiber and polymer were extruded and pelletized together. The resulting pellets were then used in an injection molding machine to produce standard test specimens. Successful composites were fabricated using up to 40% P. setaceum untreated and treated fiber in HDPE and 20% in PLA. Composites with 20% fiber in HDPE and 10% fiber in PLA were also successfully produced. For the HDPE matrix, adding fiber significantly improved flexural properties, especially when using the combined alkaline-silane treatment. This treatment led to substantial increases in the elastic modulus (69.09%) and flexural strength (209.8%) for composites with 40% fiber. With the PLA matrix, the property increases were not as significant, with the exception of the elastic modulus. Composites with 20% untreated fiber showed increases of 11.2% in tensile elastic modulus and 22.6% in flexural elastic modulus. In all cases, the impact resistance of the composites decreased with the addition of fiber. These results demonstrate the potential of P. setaceum fiber, offering a circular economy approach by reducing plastic consumption and repurposing an invasive species.