5 - Recycled synthetic polymer fibers in composites

Abstract

Green composites using renewable resources are alternatively defined here as recycled waste materials that would otherwise be consigned to landfill. Thermoplastics are collected and isolated from waste in relatively pure and consistent form. They are converted to fibers suitable for textile and composite preparation. Poly(ethylene terephthalate) and polypropylene are most applicable. Separation, purification, extrusion into pellets and then melt spinning into fibers are the processing sequence. The fibers can be formed with various diameters, orientations, hollow forms, crimps, and twists. Fibers can be recycled from existing textiles by shredding, carding, and felting into precursor forms. The fibers find application in traditional polymer composites, concrete, single-fiber composites, laminated technical textiles, and thermoformable carpets. The concept of a fiber composite as a two-phase material is developed by including textile combinations, either woven or felted. Recycled synthetic thermoplastic fibers are ubiquitous and increasingly found in consumer products, though widespread when industrial products are considered.