Carpet Waste And Composition

During carpet manufacturing, the edges of a tufted carpet need to be trimmed and the face yarns sheared. This waste is approximately 60% edge trim and 40% shear lint. In the Dalton, Georgia, region where there is a high concentration of carpet manufacturing activities, over 20,000 tons of carpet manufacturing waste is generated every year. The carpet waste from the fitting process is concentrated in the automotive and prefabricated housing industries [11, 12]. During the fitting process, the carpet is formed and cut into various irregular shapes, and waste is generated as a result. The largest amount of carpet waste, however, is from the discarded postconsumer carpet. It is estimated that about 2.3 million tons of carpet and rugs were placed in the municipal solid waste stream in 1996, of which only 1% was recovered for recycling.

Carpet is a complex, multicomponent system. The tufted carpet, the most common type (90%) as shown in Figure 16.1, typically consists of two layers of backing (mostly polypropylene fabrics), joined by CaCO3-filled styrene-butadiene latex rubber (SBR), and face fibers (majority being nylon 6 and nylon 6,6 textured yarns) tufted into the primary backing. The SBR adhesive is a thermoset material, which cannot be remelted or reshaped. The waste containing the SBR (postconsumer and some industrial waste) has not found suitable uses, and it forms the major part of the carpet waste going into the landfills. Figure 16.2 shows the typical masses for the various components [13].

Because about 70% of the carpet produced is for replacing old carpet, it is important to understand the amount and types of carpet produced. Using the typical life of a carpet of 5-10 years, one can estimate the amount of carpet being disposed of currently and to be disposed of in the next few years. According to carpet industry statistics [14], the total fiber consumption in 1999 was about 1.7 million tons: nylon 57%, olefin 36%, polyester 7%, and wool 0.4%. Among the nylon face fiber, about 40% is nylon 6 and 60% is nylon 6,6. In recent years, the use of polypropylene (labeled as polyolefin or olefin) in carpet is increasing, as tabulated in Table 16.2 [15]. Based on the aforementioned data, one expects the current rate of carpet disposal to be about 2 million tons

Face yarn (nylon) Primary backing (PP)

Adhesive (CaCO3/latex) Secondary backing (PP)-»C

Figure 16.1. Typical carpet construction.

Face yarn 1018

Face yarn 1018

Figure 16.2. Component mass/area for a typical carpet (g/m2). Total is 2223 g/m2.

Table 16.2 Relative Market Share of Top Three Synthetic Fibers Used by the U.S. Carpet Industry [15]

Year

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