Polyamide Recycling

Physical Recycling
PA 6,6 can be extracted from carpets. It is then melted and made into pellets to be used for injection moulding of engineering components. This type of recycling always results in loss of quality, however, and so these products would not be suitable for further recycling by this method.

The German company, Polyamid 2000, uses this approach for PA 6,6 in their plant at Premnitz (near Berlin), which has been in operation since December 2000.

Over 40% of PA 6 and 6,6 produced is used to make carpets, both industrial and domestic. In Europe, the area of carpet thrown away annually is enough to cover 200,000 football pitches, and up until recently it has mostly gone into landfill sites (70%) or incinerators.

The recycling of polyamide has the potential for considerable impact on the use of non-renewable resources, and on waste disposal. Collected carpet can be processed to produce various products, depending on the composition.

Chemical Recycling
Once it has been separated from its backing materials, PA 6 is relatively easy to depolymerise. This produces fresh caprolactam that can be used to manufacture PA 6 with no loss in quality, and so is suitable for further recycling. Polyamid 2000 operate this process for recovered PA 6.

The comparable process for PA 6,6 is not as easy, but DuPont have developed and patented a process that depolymerises any mixture of PA 6 and 6,6 using ammonia. The result is fresh caprolactam and 1,6 diaminohexane for manufacture of PA 6 and 6,6 respectively.

diagram: carpet recycling
diagram: carpet recycling

Recycling Facts and Figures

  • Every 10 tonnes of carpet waste produces about 0.8 tonnes of PA 6 and 1.0 tonnes of PA 6,6 (Polyamid
  • 2000 process)
  • DuPont's Carpet Reclamation Program processes over 700 tonnes of carpet a month, with carpets from over 80 collection sites in the United States
  • Several companies supplying industrial carpets now guarantee that old carpet removed will be recycled.
  • Waste material from processing can be made into fuel pellets for use in cement kilns and coal-fired power stations.
  • Polyamide recycling has the potential to achieve genuine closed loop recycling
 diagram: closed-loop recycling  

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