Conventional Production
The chemicals needed to make PA 6 and PA 6,6 are caprolactam, hexanedioic acid (adipic acid) and 1,6-diaminohexane (HMD). These are derived from benzene, so all polyamides have, until relatively recently, been made from petrochemical-derived feedstock. Find more about the production of benzene by clicking here.

Feedstock from Recycling
Both PA 6 and PA 6,6 carpets can be depolymerised to make the monomers from which they were originally manufactured. There are important advantages in pursuing this approach:

  • Many thousands of tonnes of used nylon carpet are disposed of in landfill sites, and more densely populated countries cannot continue to bury such quantities of waste. Legislation is being introduced to prohibit disposing of carpet in this way, making recycling a priority to help reduce waste.
  • Oil is the source of petrochemical feedstock, and this is a non-renewable resource. There are still many products for which alternatives are not yet available, and so recycling polyamide waste helps to conserve stocks.
  • The recycling process generates other useful products that can be used as fuels and construction materials, saving resource depletion in these areas.

For more about polyamide recycling, click this link.

Biological Feedstock
The Draths-Frost synthetic route allows one of the main chemicals to be made from plant-derived glucose. This can be obtained from crops grown for the purpose (maize, sugar cane) or from agricultural waste.

One of the advantages of using bio-feedstock is that when wastes from the process are burnt to produce heat (a common practice aimed at reducing energy costs), the carbon dioxide released is not adding to atmospheric levels - it was fixed from the atmosphere as the crop grew. The process is regarded as being carbon-neutral.
photo:  crops photo:

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