Composites from Postconsumer Polypropylene Carpet and Bottle-Waste Polyolefins

Each year, a significant number of carpets and rugs are landfilled in the United States because their recycling poses difficult challenges. The most commonly recycled plastic is poly(ethylene terephthalate) (PET), which typically comes from plastic bottles, is already easily recycled, and even circularly used to make new bottles. However, the bottle caps, typically made of polyolefins, are often mixed with other materials such as labels, ink, and remnant products, which create challenges for separation and recycling. This research focused on making composites using postconsumer polypropylene carpets (cPP) and mixed polyolefins (rPO) recovered from postconsumer bottle waste by compression molding. The quality of the molded samples was characterized by flexural strength and modulus, creep behavior, and optical microscopic images. The effects of soil contamination and mixing with a polyolefin elastomer on the mechanical properties of the composites were also examined. These samples showed significant mechanical properties suitable for structural applications with strength and modulus values greater than those of most bulk commercial thermoplastics. In addition, we demonstrate that the carpet backing enhances the mechanical properties of the components. So rather than being a “cost” to recycling, the backing can be a benefit.