'''Polyamide 6 and 6,6''' are manufactured, man-made fibres that are formed from a chemical process using carbon, hydrogen, oxygen and nitrogen atoms. They differ in that they each begin with different polymer building blocks.[1 ] The manufacturing process of Polyamide 6 and 6,6 is highly chemical and is derived from petroleum, a non-renewable resource. Also, the fibre and its resulting fabric are non-biodegradable. Efforts to address sustainability in these areas could help the overall impact of polyamide on the environment.
== Benefits ==
Polyamide 6 and Polyamide 6,6 share a lot of the same fibre characteristics. They have strong wear resistance, abrasion resistance, chemical resistance, heat resistance, are lustrous, have a high melting point, and are resilient.[1]Polyamide 6,6 has greater resilience, a higher melting point, and lower stain permeability than polyamide 6, which makes polyamide 6,6 perfect for carpet.[2]The most notable characteristic of both polyamide 6 and 6,6 is versatility. Although originally developed as an “artificial silk,” it has been used for a vast variety of applications. Polyamide fibres are used for garments, sheer hosiery, parachute cloth, backpackers' tents, bridal veils, musical strings, rope, broom and tooth brush bristles, Velcro and many other applications.[3]
<br/>Polyamide 6 and 6,6 blend well with other fibres, and their chief contributions are strength and abrasion resistance.1
Polyamide 6 and 6,6 are machine washable, dry quickly, need little pressing, and holds shape well since they neither shrinks nor stretches, thereby minimizing water and energy use associated with consumer care and washing.[4]
Due to their durability and abrasion resistance, some Polyamide 6 and 6,6 products have the potential to last and be worn many times, optimizing the energy and resources embodied in the product.
====Durable water repellents (DWR)====
Durable water repellents (DWR) are applied to polyamide 6 and 6,6 garments and products to allow for breathability and water repellency. Fluorochemicals are commonly used in these water-repellent finishes and waterproof membranes (thin films or coatings attached to the back of fabrics to prevent water from passing through). Two fluorinated compounds are of most concern, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), since they are known to have persistent, bioaccumulative and toxicological effects on the environment. The European Union has banned PFOS and some countries in the EU have also banned PFOA. [6]
Waterproof membranes are engineered to be breathable, and are commonly derived from petroleum and made using PFOA.
===End of use===
Synthetic fibres are from a carbon-based chemical feedstock and are considered non-biodegradable.[7 ] <br/>Polyamide 6 and 6,6 products have the durability to last many years, however if they are discarded, could sit in the landfill for decades.Discarded polyamide products increase load on landfills, contribute to land and water contamination and possibly toxic emissions into the air.[8 ] <br/>When incinerated, polyamide 6 and 6,6 emit chemicals, such as nitrogen oxide, formaldehyde, hydrogen cyanide and acrolein, that are poisonous and possible carcinogens.[9]
==Alternatives to virgin polyamide==
===Mechanical recycling===
Polyamide 6 and 6,6 can be effectively collected, cleaned, cut, re-melted and remolded to make yarns. However, the fibre is “downcycled” in this manner, which means that its physical structure breaks down, and eventually the product must be discarded to landfill.[10]
Collection, sorting and purifying discarded synthetic garments (i.e., post-consumer waste) is currently cumbersome. Infrastructures for labeling, collection and sorting need to be improved so that the post-consumer raw material source can scale to be economically viable.
===Chemical recycling===
There is potential for polyamide 6 to be chemically recycled. Chemical recycling involves breaking the polymer into its molecular parts and reforming the molecules into a yarn of equal strength and quality as the original, in perpetuity. In this process, the chemical building blocks are separated (depolymerization) and reassembled (repolymerization), forming what is known as a “closed loop” where the final stage of the product's lifecycle (disposal) forms the first stage of the next product (raw fibre). Closed loop recycled polyamide processing is currently limited to Polyamide 6, and is expensive in part because it is a relatively new technology. In addition, the infrastructure to label, collect, sort and purify discarded garments must be in place.[12]
==Optimize sustainability benefits==
• Support developments of chemically recycled Polyamide 6,6.
• Investigate developments in bio-polyamide 6, which use amino acids derived from dextrose fermentation as the starting material, instead of petroleum.[13]
• Investigate non-toxic flame retardant applications for polyamide.
• Investigate non-toxic waterproofing methods for polyamide.
• Promote OEKO-TEK certified polyamide.[14]
OEKO-TEK is an independent, third party certifier that offers two certifications for textiles: OEKO-TEK 100 (for products) and OEKO-TEK 1000 (for production sites/factories). OEKO-TEK 100 label aims to ensure that products pose no risk to health. OEKO-TEK certified products do not contain allergenic dye-stuffs and dye-stuffs that form carcinogenic aryl-amines. The certification process includes thorough testing for a long list of chemicals. Specifically banned are: AZO dyes, carcinogenic and allergy-inducing dyes, pesticides, chlorinated phenols, extractable heavy metals, emissions of volatile components, and more.
Non-toxic methods of waterproofing and flame retardancy are available.
Recycled polyamide is available globally in United States, Europe, Slovenia, Croatia, China, Japan and Israel.[15],[16]
== End use==