Recycled carpet-reinforced composites from post-consumer polypropylene carpet and recycled HDPE resin

Carpets significantly contribute to landfills, forming 3.5 % of the U.S. landfill waste, with less than 10 % being recycled. This study uses intact carpets to create functional composites as a potential solution to this problem. This research introduces a feasible method for manufacturing recycled composites through compression molding of post-consumer polypropylene (PP) carpet and recycled high-density polyethylene (HDPE) resin. Optimal molding temperature and composition ranges were identified using a comprehensive three-level full factorial design of experiments (3D-DOE), resulting in impressive flexural strength (>40 MPa) and flexural modulus (>2000 MPa). Reproducibility tests of 10 specimens yielded 41.8 +/- 2.0 MPa flexural strength and 2200 +/- 150 MPa flexural modulus. These composites, containing up to 70 % potentially-landfilled carpet and 30 % recycled resin, surpassed the performance for the strength of commercialized thermoplastics, making them suitable for structural applications. The findings present a promising approach to address carpet landfilling while reducing reliance on additives.