Recycled polyester fibre

In 1993, collaboration between Patagonia and Malden Mills (now Polartec) led to the early development of recycled polyester fibre (from Wellman Inc.) for use in Synchilla fleece made from plastic soda bottles that diverted waste from landfills. Later, PCR filament yam was made for linings and shell fabrics from 30% to 50% post-consumer materials (bottles, polyester uniforms, tents and garments) with the remainder sourced from post-industrial waste. Clothes, at end of life, if constituted from one fibre type, can be recyclable. In theory, consumers may return a polyester garment to be forwarded to a processor to be re-made into fibre or downgraded to other forms of plastic. 

Polyesters, polyamides and other poly-condensation polymers can be chemically recycled simply by reversing their synthesis process by raising the process temperature, using traditional processes such as hydrolysis, ammonolysis, acidolysis, transesterification, etc. Bayer and other interested suppliers pioneered such processes that are beyond the scope of this book. Such processes can also be used for adjusting the MW required in one application (e.g. PET-bottles) to that needed in a different market (e.g. polyester fibres). 

Polyester fibre now commands 50% of the global fibres market and its share will keep growing. Eco-sustainable polyester yam produced from post-consumer recycled PET bottles is already used for a wide range of applications in sportswear as are fibres made using bio-polymer Ingeo PEA bio-polymer. 

Teijin This is the largest and most active Japanese chemical recycler of PET. The process first nses methanolysis to produce DMTA then hydrolysis to convert this to TA. In the early 2000s, Teijin underwent major expansion in capacity, althongh the current sitnation is unclear. PET re-polymerised from recovered feedstock is sold under the Ecopet brand, which is said to include bottle-grade resins. They prodnce a range of recycle-friendly products such as laboratory and factory wear, waterproofs, and interlocked cushioning fibres, all of which are 100% polyester. Fibres may also be nsed in bottle-to-fleece... 

One well-known example of a process to recycle a single polymer system is the manufacture of polyester fibres from polyester drinks bottles. It creates an open material cycle. 

Polyester fibre does not specifically feature in thermoplastics compounds at present, but there has been some interesting work reported (by DSM). compatibilizing thermoplastic polyesters to accept polyester fibre as a reinforcement, which might greatly simplify the recycling of fabric-covered automobile interior panels (if they were moulded in polyester in the first place). 

First developed in a lab in the 1940s, polyester is one of the world s most widely used fibres. But unfortunately, polyester is made from anon-renewable resources. That s why we ve been using recycled polyester for some years now. They main source of recycled polyester is PET plastic bottles and waste raw material left over from production. Independent third party certifieation follows the Global Recycling Standard (GRS). 

The growth of recycled polyester (R-PET) fibre is already an established process in a wide range of applications and is likely to grow even further. For example, Wellman International (part of Indorama Ventures Public Company Limited) has been at the forefront of this movement. Their new Eco-core polyester staple fibre offers a guaranteed, traceable, sustainable raw material content. This validation of eco-credentials is vital for the future. Fibres that are being offered as environmental solutions need to have clear traceability, similar to that of the successful and widely used forest products, Forestry Stewardship Council (FSC) systems. 

Melt blown, spunbond, air-through thermobond, and wet-laid nonwoven fabrics made from PP and polyethylene fibres are also widely used as a support layer in membrane filtrations and in filtration media where chemical resistance is cmcial they also have the potential to be recycled to make it environmentally fiiendly, but such possibility needs to be explored. They, as well as co-polyester fibres, are frequently used as binders in thermobond nonwovens for filtration applications. 

Polyester fibres are currently being engineered to provide qualities that are similar to upholstery foams. These advanced hollow conjugated polyester fibres can contain up to 35% recycled material [2]. 

A pyrolysis technique was investigated as a method for the chemical recycling of glass fibre-reinforced unsaturated polyester SMC composites. The proeess yielded liquid products and gases and also a solid residue formed in the pyrolysis of glass fibres and fillers. The solid residue was used as a reinforeement/filler in unsaturated polyester BMC composites, and the influenee on mechanical properties was studied in comparison with BMC prepared entirely from virgin materials. 

Results are presented of experiments undertaken by Gaiker in the manufacture of sandwich panels containing foam cores based on PETP recycled by a solid state polyaddition process developed by M G Ricerche. Panels were produced with glass fibre-reinforced unsaturated polyester and epoxy resin skins, and allthermoplastic panels with PE, PP, PS and glass fibre-reinforced PETP skins were also produced. EVA hot melt adhesives and thermoset adhesives were evaluated in bonding glass fibre-reinforced PETP skins to the foam cores. Data are presented for the mechanical properties of the structures studied. 

A phase separation technique, using solvent and subsequent swelling, has been described to separate PVC from polyester fabric, primarily to recycle the fabric (340,355). A technique for recycling PVC coated glass fibre fabric has been described, based on compression or injection moulding, with addition of an acid absorber (hydrotalcite) (49). 

Research on the pyrolysis of thermoset plastics is less common than thermoplastic pyrolysis research. Thermosets are most often used in composite materials which contain many different components, mainly fibre reinforcement, fillers and the thermoset or polymer, which is the matrix or continuous phase. There has been interest in the application of the technology of pyrolysis to recycle composite plastics [25, 26]. Product yields of gas, oil/wax and char are complicated and misleading because of the wide variety of formulations used in the production of the composite. For example, a high amount of filler and fibre reinforcement results in a high solid residue and inevitably a reduced gas and oiFwax yield. Similarly, in many cases, the polymeric resin is a mixture of different thermosets and thermoplastics and for real-world samples, the formulation is proprietary information. Table 11.4 shows the product yield for the pyrolysis of polyurethane, polyester, polyamide and polycarbonate in a fluidized-bed pyrolysis reactor [9]. 

A. M. CunUffe and P. T. Williams, Characterisation of products from the recycling of glass fibre reinforced polyester waste by pyrolysis. Fuel, 82, 2223-2230, (2003). J. H. Harker and J. R. Backhurst, Fuel and Energy, Academic Press London, 1981. A. C. Albertson and S. Karlsson, Polyethylene degradation products, In Agricultural and Synthetic Polymers, ACS Symposium Series 433, J. E. Glass and G. Swift (eds), American Chemical Society, Washington DC, 60-64, 1990. 

CMC and water dispensible polyester based size materials are also used for sizing of synthetic fibre materials. They are insoluble in acidic form and soluble in the presence of dilute alkali and can be removed from the fabric at about 60 C. They are, however, precipitated in presence of metal ions in the washing bath and hence the addition of chelating agent is recommended to nullify its effect. Synthetic detergents of either anionic or non-ionic type may be used to remove the polyester size from the fabric. The CMC can be reclaimed, recycled and reapplied from other size material. 

The aromatic polyesters such as poly(ethylene terephthalate) (PET) were commercialized from about 1946 as fibres, but, because of the high processing temperatures, it was only some 20 years later that they appeared as engineering thermoplastics. The dominance of PET in beverage containers ensures the importance of the synthesis, processing and recycling of PET. Polyesterification is a suitable stepwise reaction to illustrate the principles of this industrially important polymerization. Applications in reactive processing will then be considered. 

Importantly, fibres are commonly blended together in order to give fabric more desirable qualities appropriate for apparel applications. For example, cotton and polyester blends have the breathability and wearability of cotton but will crease less and so require less pressing. A smaU percentage of petrochemical-based fibre elastane is often blended with other fibres for added stretch in both wovens and knits. This wide variety of fibres and fibre blends used in textiles for apparel makes effective recycling difficult due to the complexity of separating and sorting constituent fibres from textile blends. 

This process is used to recycle fabrics made from natural fibres such as cotton and wool as well as synthetic fibres including polyesters, nylons and blended fibres. Hawley (2006) describes the mechanical processing technique used in facilities in Prato, Italy, where acrylic textiles are shredded down to fibre. In hw example, acrylic garments were sorted and cut up, mechanically shredded to fibre, and then re-spun into acrylic yam for weaving into blanketing (Hawley, 2006). 

The recovery and use of plastic bottles into RPET yams has had strong uptake from a number of apparel companies. Currently, OLR of PET bottles to fibre has had the greatest success for reuse as a material in the fashion sector, with an open loop of waste from the first product (PET bottles) used as feedstock for the second product system (polyester fabric to garment). A common approach is to blend the recycled yams with virgin fibres to create textiles that are of apparel quality. 

Biological CLR refers to fibres that can be safely composted at end of fife to return nutrients to the soil. Technical CLR refers to the synthetic products that are not biodegradable. In textiles, this is frequently the synthetic polymer-based fibres such as polyester, acrylic and nylon. Blending of the two kinds of streams is referred to by McDonough and Braungart (2002) as a monstrous hybrid , meaning that the two kinds of waste streams cannot be effectively separated for ease of recycling. In the apparel context, monstrous hybrids abound in the form of cotton/polyester, or viscose/polyester, or cotton and spandex blends. 

Technological innovations continue to be explored in the field of textile recycling. A key barrier to effective recycling is the proliferation of textiles in different fibre blends that are difficult to separate for recycling, such as cotton and polyester. Researchers have examined how to separate the cotton from the polyester using environmentally sound approaches to dissolve the cotton in order to reclaim the polyester for recycling (De Silva et al., 2014). 

Virgin nylon fibre, like polyester, is made from crude oil (petroleum). The benefits of recycling nylon come from the reduced energy needed to produce the final fibre, the reduced dependence on oil, and the diversion of waste from landfill. The final product can be recycled again at the end of its hfe. However, due to polymer chemistry, nylon is more difficult to recycle than polyester. There are two main recycling methods explained by the Textile Exchange ... 

Textile fabrics within the interiors of cars are fully described by Fung and Hardcastle and more recently by Shishoo. While all conform to the IMVSS 302 standard or its equivalent, seating materials usually comprise polyamide or polyester head- and sideliners and door panels, polyester and carpet face stractures, polypropylene or polyamide. It is noteworthy to add that the intense internal temperatures and sunlight exposure experienced by closed cars when parked ensures that polyester is a preferred interior fibre, and this use of a single fibre type also assists with the need to ease the recycling and reuse of cars when scrapped. Table 11.10 lists typical examples. 

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