Challenges and Solutions for Recycling of Manmade Fiber/Synthetic Blends/PET

Do you know about textile recycling?  Is it possible to recycle man-made or synthetic blend fibers? Is this type of fiber required to be recycled?  Yes of course. Textile recycling can play a very important role in today’s growing demand for sustainability. Generally, the average lifespan of a garment is about three years, while the garment is 100 percent natural; it can decompose after the life cycle.  But this challenge becomes more serious when garments made using a mixture of natural fibers and synthetic fibers are dumped.  Nylon, Rayon, Acrylic, Spandex, and Neoprene have been used to manufacture our garments for the past 80 years. Currently polyester accounts for 55% of the global fiber market due to low production costs and availability, which is called the king of synthetic fabrics. Some properties of synthetic fabrics like water resistance, durability, etc make them popular with both manufacturers and consumers.

What is Textile Recycling?

Textile recycling is the process of material collection and processing through which old clothing and other textile materials are reused or recovered to convert them into usable textile materials. Textiles for recycling are generated from two primary sources such as post-consumer which includes clothing, car upholstery, and household goods and pre-consumer which includes scraps made as by-products of yarn and fabric manufacturing, as well as post-industrial scrap textiles from other industries.  Recycling is the basis of the textile recycling industry, its essential steps involve donation, collection, sorting and processing of textiles and then transport to the end users of used clothes, rags, or other salvaged materials. As there is no loss of quality during the recycling process, these products are used for a long time.

Fiber Blends and Challenges in Textile Recycling:

Fibers in textile products often consist of bi- or multi-component and mixed-materials yarn. Products are functionalized by combining the properties of fiber components with this type of material blend. Fiber construction increases the variety of product materials (clothing textiles) such as Haberdashery (zip, button, bias binding), Multilayer constructions (membrane, lining or wadding on jacket), Functional coatings (water-repellent coating), Color, print and application (dyed textile, printed or embroidered logo). A prerequisite for sustainable recycling is to make the material flow as pure or compatible as possible. Mixing of materials in this process can create challenges or make recycling uneconomical, non-natural or technologically unfeasible.

How to perform recycling on the Products made from different Synthetic and Blended fibers?

According to Amrei Becker, a textile engineer at RWTH Aachen University in Germany, products made with man-made fibers of synthetic blends can be recycled using any of four methods – 1) Mechanical recycling (tearing)  2) Thermo-mechanical recycling (regranulation) 3) Physico-chemical recycling (solvent-based separation) and 4) Chemical recycling (back to Oglimer/monomer).

Mechanical recycling of textiles is the process in which textile fabric is shredded for recycling into fibers without the use of chemicals.  It is the carding process that can produce yarn for knitted or woven fabrics.  The input material in this process consists of textiles made of natural or synthetic fibers that are torn into individual fibers and shortened in length due to mechanical damage. The waste fabric is then cut into small pieces and sent to the garnett machine.  These machines perform heavy and rough carding operations by tearing the cloth with opposite sets of hard sharp teeth and converting it into fiber. Since fiber length is the critical factor for yarn fineness, collected fibers are blended with virgin fibers with higher fiber length at different blending percentages.  The more virgin fiber used, the finer the yarn.  Also, the price of recycled yarn is 15-18% lower than yarn made from virgin fiber of similar composition and thus can have a huge impact on the price of the fabric.

Tech Providers:

1) LAROCHE S.A. (renowned France-based Company) provides technology for mechanical recycling of synthetic textiles and cotton textiles.

2)The Hong Kong Research Institute of Textiles and Apparel (HKRITA), in collaboration with fashion giants such as H&M, developed a mechanical garment-to-garment recycling system that acts as a mini production line to process post-consumer clothing into sanitized recycled garments.

Thermo-mechanical recycling (regranulation) is a process in which synthetic fibers or textiles are melted, filtered and extruded as input material. The output element will be contaminated if the input element is contaminated. In thermo-mechanical recycling, the plastic is melted and the molecular structure of the plastic remains intact. Various post-industrial wastes can be recycled in this way. Here the material is melted by built-in heating elements and frictional heat and a degassing system is attached to the extruder which removes volatile matter. After extrusion, the material is melted and cooled in a water bath and then cut into small strands with a rotating knife. It can also reduce the cost of raw materials and waste disposal.

Tech Provider:

1) Swiss technology group OC Oerlikon’s subsidiary offers cutting-edge solutions using the regranulation process for recycling synthetic textiles and PET.

Physico-chemical recycling (solvent-based separation) is a process in which a mixed material stream of synthetic/natural fibers is used as input material, depending on the solvent and polymer. In this process, the desired textile material is separated by solvent. The textile waste is converted into RePAN-pellets.  It undergoes a spinning process and finally, the main fiber is obtained.  This method of recycling is used to recover polymer waste streams, to achieve qualities such as virgin plastic quality, and to achieve high-quality polymer qualities using selective solvents.

Tech Providers:

1) Switzerland-based Sulzer Chemtech offers breakthrough DEVO technology for solvent-based separation/recycling.

2) UK-based Worn Again Technologies has gained a name for itself in this space and is working with stakeholders in the textile industry to provide solutions for Physico-chemical recycling.

Chemical recycling is a process in which polymers are broken down into oligomers or monomers that are used to obtain a virgin quality polymer.  The output products of this recycling process are often the same in quality as their virgin counterparts and have no loss of physical properties. Chemical recycling involves breaking down plastics into chemical intermediates (oligomers) or their basic building blocks (monomers) using chemicals, enzymes, controlled environments, etc.  There are various processes for chemically recycling PET textiles such as Hydrolysis, Alcoholysis (glycolysis/methanolysis) and Aminolysis.  In terms of technology, it is much more advanced than mechanical recycling. The oligomers or monomers have to be purified by the filtration/separation process.  The purified oligomers or monomers can then be processed into new plastics or other chemical products.  In this way, high-quality secondary raw materials can be gained, which also supply as raw materials for the spinning process of new textile fibers.  Generally, only individual fiber types can be dissolved and processed from chemically recycled textile blends.

Tech Provider:

1) Aquafil Group of Italy is one of the leading companies that use proprietary technology to produce commercially chemically recycled nylon.

The Urgency to Recycle Textiles….

The textile industry is the most polluting industry in the world.  To reduce these pollution and greenhouse gas emissions, the importance of textile recycling is increasingly recognized.  The textile industry requires a large amount of water, energy and chemicals which have a significant impact on the environment.  The two main fibers in the textile industry are cotton and polyester, which represent more than 85% of global fiber production.  Natural fibers can release methane and CO2 gases into the atmosphere and take weeks to years to decompose. On the other hand, Synthetic textiles do not decompose easily and can release toxic substances into groundwater and surrounding soil.  When synthetic fiber products are dumped in landfills, such waste takes 100 years to decompose which pollutes the atmosphere and if not degraded, it accumulates causing infectious diseases and odors. Textile recycling provides some of the following benefits:

  • The manufacturing process is eco-friendly, simple and fast which saves energy and reduces water consumption.
  • Using PET bottles for fiber production will reduce the amount of plastic waste.
  • Reduces demand for textile chemicals like dyes, fixing agents etc. which reduces process cost.
  • Up to 95% of textile waste can be recycled which will reduce the pressure on new resources.
  • Using waste as raw material avoids pollution and does not incur costs for purchasing raw materials.
  • The use of recycled yarn avoids the use of virgin fibers.

References:

  1. https://www.textiletechnology.net/fibers/trendreports/ita-current-challenges-and-solutions-for-the-recycling-of-mixed-synthetic-textiles-31929
  2. The Basics of Textile Recycling (thebalancesmb.com)
  3. https://apparelresources.com/business-news/sustainability/recycling-man-made-fibres-synthetic-blends-pet-challenges-solutions/