Carpet recycling technologies

A large amount of fibrous waste is generated each year, consisting of a variety of synthetic and natural polymers. Frequently, different types of polymers and other materials are integrated to form an article, such as blended textiles, carpets, conveyer belts, to name a few. Much of the textile waste collected could be re-used directly, be used as wipes, or be shredded for filling or nonwoven applications. Post-consumer carpet, on the other hand, is a more complex system that often requires extensive processing to convert it into products. 

According to the US carpet industry statistics, the total fiber consumption in 2001 was about 1.4 million tons Nylon 60%, Olefin 29%, Polyester 10%, and Wool 0.3%. Among the nylon face fiber, about 40% is nylon 6 and 60% is nylon 6,6. About 70% of the carpet produced is for replacing old carpet, typically after 5-10 years of service. The rate of carpet disposal is about 2-3 million tons per year in the USA, and about 4-6 million tons per year worldwide. 

The type of carpet is classified according to the type of face fibers used. A nylon 6 carpet, for instance, contains not only nylon 6 face fibers but also backing fibers (polypropylene) and adhesive (latex and filler). Nylon generally performs the best among all synthetic fibers as carpet face yam, but it is also the most expensive. Typical prices per kg for the plastic resins are Nylon 2.50, Polyester 1.20, and Polypropylene 0.75. This price list provides a perspective on the economics of recycling as well. For example, if it takes the same processing effort to convert the 

2 Component mass/area for a typical carpet (g/m ). Total is 2224 g/m2. 

3 Recycling technologies according to product value, processing steps and cost. 

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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. 

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. 

As the search of technology for carpet recycling continues, carpet also is being redesigned for better recyclability. Reuse of reconditioned carpet is being considered for extending its life. 

Hawn K. (2001), An Overview of Commercial Recycling Technologies and Textile Applications for the Products , Presentation zt 6th Annual Conference on Recycling of Polymer, Textile and Carpet Waste, Dalton, GA, April 30-May 1. 

Bodrero S., Canivenc E. and CanseU F. (1999), Chemical Recycling of Polyamide 6.6 and Polyamide 6 through a Two Step Ami-/Ammonolysis Process , 4th Annual Corfer-ence on Recycling of Fibrous Textile and Carpet Waste, Dalton, GA, May 17-18. Schut J. H. (1993), A Recycling First Carpets , Plastic Technology, 22-25, April. 

Polymer Plastics Technology and Engineering 38,No.3, 1999,p.471-84 RECYCLING NYLON 6 CARPET TO CAPROLACTAM... 

Schut, J.H., Big German Plant May Relieve U S. Bottleneck in Recycling Carpet Nylon, Plastics Technology Online, New York, NY, May 2002. (www.plasticstechnology.com/articles)... 

Finally, caprolactam could also be obtained by recycling polyamide-6 (PA-6) and polyamide-6,6 (PA-6,6) waste. Rhodia recycles about 30 000tons annually of PA-6 wastes in three different places in Europe. PA-6 production waste as well as used pure PA-6 wastes (fish nets and pure PA-6 fabrics) are used as starting products. PA-6,6 is also recycled. DSM and AlliedSignal opened a pilot plant in Richmond, Virginia, in 1997, where PA-6 carpets are depolymerized. The technology involves chemical processing of complete carpets without an expensive mechanical separation of fibers from the other carpet components. 

A solvent-fi ee adhesive was used for laminating vinyl sheet to wood. A new technology of recycling waste carpets and textiles was developed based on coating individual yam fibers by an adhesive containing solvent The high surface contact area produced materials with excellent mechanical properties. 

Based on today s technology and associated economics, it is impossible to recycle all this material back into carpet itself. Therefore, a key element of the CARE approach will be to aid in the development of non-carpet products containing post-consumer carpet. By facilitating the development and market penetration of such products, a demand for post-consumer carpet as a feedstock will be created. Such demand will facilitate the aeation of the necessary infrastructure required for the collection, sorting, processing, and supply of these materials. 

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