Carpet recycling carpets

In both the materials used and the construction process, sustainability and efficiency will become standard. Improvements mjob site management and building design will reduce waste and cost of construction. Materials such as engineered wood, recycled carpeting, and cellulose insulation, which have lower environmental impact, will become cheaper and more widely available. Not only are buildings constructed with such material friendlier to the environment, they also provide higher-quality, lower-cost solutions. 

Important solvolysis reactions for nylons are hydrolysis, methanolysis, glycolysis, aminolysis, ammonolysis, transamidation, and acidolysis.17 Hydrolysis of nylon-6 with steam in the presence of an acid catalyst to form caprolactam is tlie preferred depolymerization approach. However, when recycling carpet face fibers, file fillers in the polymer may react with file acid catalyst and lower the efficiency of the catalyst. 

DSM and Allied Signal have developed carpet identification equipment that can identify specific plastics. Particularly carpet made of nylon 6 (or nylon 66) fibres are separated, cut into pieces, isolated, and converted by polycondensation into their monomeric components. The monomers can then be reused in the production of nylon. DSM and Allied Signal opened the world s first large scale carpet recycling plant in Augusta, Georgia, US in November 1999. This plant has a capacity of 90,000 tpa nylon 6 carpet waste (109). 

The problem of carpet recycling is considered and the different methods being proposed or commercially utilised are discussed. The main component of the carpet waste is fibres of nylon-6 and nylon-66. The review of the literature includes a limited amount of journal publications, which focus primarily on fundamental aspects, and a large number of patents, which describe the available technologies. The most promising recycling techniques (depolymerisation, extraction, melt blending and mechanical separation) are described. 48 refs. 

FIRST LARGE-SCALE CARPET RECYCLING PLANT... 

NYLON SUPPLIERS TAKE LEAD IN CARPET RECYCLING... 

CARPET RECYCLING OEEERS MARKETING ADVANTAGE TO NYLON... 

The Polyamid 2000 plant in Premnitz, Germany is another nylon 6 carpet recycling facility. For an investment of US 200 million in 2000, the plant was designed to process 264 million pounds per year of carpet and produce 20 million lb/yr of nylon 6 plus 25 million pounds of nylon 6,6 and other engineering plastics271. 

In May 2002 the plant was only running at 75% of capacity (15 million lb/yr of nylon 6). One problem was that the nylon content in the carpet was lower than expected. Another problem is that landfill fees have dropped from 90/ton to 45/ton. It is estimated that landfill fees must be at least 75/ton for carpet recycling to be viable271. 

Schut, J.H., Big German Plant May Relieve U.S. Bottleneck in Recycling Carpet Nylon,... 

Tullo, A. 2000. DtiPont, Evergreen to recycle carpet forever. Chemical and Engineering News, January 24 23-24. 

Cost is another concern associated with the use of recycled carpet waste fibers in concrete. Currently a vast amount of carpet waste is disposed of each year and therefore the cost of raw material for the recycled fibers is negligible. The disassemble process to convert the waste into fibers suitable for concrete reinforcement requires only simple, inexpensive shredding operation. Therefore the cost of the recycled fibers will remain very competitive with virgin fibers for FRC. 

FRC using recycled carpet waste fibers has also been used in the construction project of a 11,000 m2 building. Conventional equipment and procedures were used in the construction. The project consumed about 20 tons of carpet waste as concrete additives. The waste fibers were directly added into concrete mixing trucks. The mixing, pouring and finishing went smoothly the compressive and flexural strengths exceeded specifications and improved ductility and shatter resistance of the material were evident. This project has demonstrated that low-cost carpet waste... 

Residential carpets are continuing to be more visible in MSW. Carpets are quite complex with polyamide/PP/PET face libers, PP backing, latex adhesive, and calcium carbonate as tiller. In addition, the recycled carpet will have a higher amount of dust particles. There have been efforts in the United States to collect residential carpet. As it is very difficult to separate the different components of the carpet, the reasonable way is to shred the carpets and pelletize it so that the pellets can be used in products such as plastic lumber. Only a small percentage of the face materials (nylonb and nylon 66) are recovered and recycled. 

Realff, M. J., Ammons, J. C., and Newton, D. (1999), Carpet Recycling Determining the Reverse Production System Design, Journal of Polymer-Plastics Technology and Engineering, Vol. 38, No. 3, pp. 547-567. 

YoujiangW (1993) Fiber reinforced concrete using recycled carpet industrial waste and its potential use in highway construction. Symp Proc on Recovery and effective reuse of discarded materials and by-products for construction of highway facdities, October 1993, Denver, CO... 

Products from recycled carpet waste. [Data from Riccirdelli, X E King, M H ... 

McNeil, S.J., Sunderland, M.R., Zaitseva, L.I., 2007. Closed-loop wool carpet recycling. Resources Conservation and Recycling 51, 220—224. 

Companies can resolve their sourcing problems by developing their own infrastructure for collection. These collection schemes typically involve customers who supply dean and relatively homogeneous material which can be made into useful products [23, 24]. One example is the DuPont Partnership for Carpet Reclamation, which recovers nylon carpets from carpet companies for mechanical and chemical recycling. This scheme generates material approved for under-the-bonnet automotive applications. 

Because of the higher value of nylon resin in comparison with other polymers used in carpet, nylon carpet has been looked at as a resource for making virgin nylon via depolymerization. The majority of polyamides used commercially are nylon 6,6 or nylon 6, and the largest supply of waste for recycling of nylons is obtained from used carpets. The waste carpets are collected, sorted, and then subjected to a mechanical shredding process before depolymerization. 

Applications of Dopolymerized Nylon 6 Chemical recycling of nylon 6 carpet face fibers has been developed into a closed-loop recycling process for waste nylon carpet [25, 30-32]. The recovered nylon 6 face fibers are sent to a depolymerization reactor and teeated with superheated steam in the presence of a catalyst to produce a distillate containing caprolactam. The crude caprolactam is distilled and repolymerized to form nylon 6. The caprolactam obtained is comparable to virgin caprolactam in purity. The repolymerized nylon 6 is converted into yam and tufted into carpet. The carpets obtained from this process are very similar in physical properties to those obtained from virgin caprolactam. 

United Recycling Inc. (URI), which was in operation from the early 1990s to 1999, introduced two extruded blends (URI 20-(X)l and URI 10-(X)1) from postconsumer carpet waste for injection molding in 1993 [61]. These were the first commercial recycled carpet compounds. The process used both polypropylene and nylon carpet. Their products were described as proprietary blends containing polypropylene. The composition and properties of the two compoimds are listed in Table 16.5. The molding compounds developed by URI were used to extrude carpet tack strip. 

Figure 16.4. Extrusion process developed by Monsanto for recycling carpet waste [63],...

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