RECYCLING OF TEXTILE MATERIALS Prof Bojana Voncina University

RECYCLING OF TEXTILE MATERIALS Prof. Bojana Voncina, University of Maribor Department for textile materials and design 1

Global demand for manufactured fibers rised 4. 7 percent annually through 2012 This stimulates the economy (projected to add 10 -20 new factories to meet the world market demand) and it also gives rise to the increased problem of apparel and textile disposal. The textile industry is one of the biggest GHG emitters on Earth Apparel and textiles account for approximately 10 percent of the total carbon impact. 2

Textile recycling statistics p Mankind used some 72 million tons of fibre in 2007, the increase rate of 7 -10% p Per capita consumption of fiber in developed country is up to 40 kg (in average 11 kg/capita); p Textile recycling industry annually diverts only about 15 -30% of the total post-consumer annual textile waste; p Textile recycling industry is able to process 93% of the waste without the production of any new hazardous waste or harmful byproducts. 3

Pre-consumer waste Post-consumer waste 4

Heat values of Fuels/fibres Fuels-Fibres Heat values [MJ/kg] Heating oils 42 Wood 17 -19 Paper 13 -18 Cotton 17 Woll 23 PES 22 -23 PA 29 -31 PP 43 PVC 17 -23 -26 5

Energy for garment production and use Transportation by air (131. 040 k. Wh/tone) p Finishing (56. 400 k. Wh/tone) p Washing (46. 400 k. Wh/tone) p Ironing (43. 000 k. Wh/tone) p Garment production (22. 800 k. Wh/tone) p By lories (12. 900 k. Wh/tone) p By trains (8. 500 k. Wh/tone) p Shipping (960 k. Wh/tone) p 6

The waste hierarchy refers to the 3 Rs of reduce, reuse and recycle, which classify waste management strategies according to their desirability 4 Rs: 3 Rs + Re-thinking 6 Rs: 3 Rs + Residual waste management, Resources and Regionalism Pyramid model for textile recycling categories, by quantity. 7

Textile recycling 8

Methods of textile recycling: p p Second hand clothing Mechanical recycling n n p Chemical recycling n n p Fabrics to fibers (convertion to new products) Re-melting (extrusion) hydrolysis, methanolysis, aminolysis, pyrolysis Composting 9

Second hand clothing p p the export of clothing to un-developed countries has threatened the traditional dress for many indigenous cultures and at the same time may threaten the fledgling textile and apparel industries of those countries. Second hand shops in UK n British Heart Foundation, Cancer Research UK, Roy Castle Lung Cancer Foundation, Age UK (formerly Age Concern and Help the Aged), Oxfam, Save the Children, Scope and Sue Ryder Care. Many local hospices also operate charity shops to raise funds. 10

Convertion to new products (up-recycling) re-design of used clothing; current fashion trends are reflected by a team of young designers who use and customize second-hand clothes for a chain of specialty vintage clothing stores. This concept is common among boutiques with a youth-oriented target market. 11

Convertion to new products (fiber 2 fiber) breakdown of fabric to fiber through cutting, shredding, carding, and other mechanical processes. The fibers are re-engineered into value-added products (stuffing, automotive components, carpet underlays, building materials such as insulation and roofing felt, and low-end blankets. Basic construction of a card and its parts Carding action 12

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Re-melting (extrusion) p p Melt processing by extrusion converts thermoplastic polymers into resin pellets. If more than one type of polymer is blended together, the process is also referred to as compounding (the resulting pellets are called compounds). Plastics extrusion is a high volume manufacturing process in which plastic material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, fence, window frames, adhesive tape, fibres, . . 14

Plastics constitute between 14 and 22% of the volume of solid waste. In 1990, 1 to 2% of plastics, 29% of aluminum, 25% of paper, 7% of glass, and 3% of rubber and steel as post consumer wastes were recycled. p Obviously, increasing the amount of plastics recycled would appear to be the answer. p However, a major handicap in the reuse of plastics is that reprocessing adds a heat history, degrades properties and makes repeat use for the same application difficult.

p p In response to the contaminants issue in plastic recycling, plastic products are being designed as "reuse-friendly". Another factor in the recycling equation is the economic trend of increasing tipping fees at landfills. The use of recycled plastics is only limited by the imagination of the designers and end users of the plastics.

Labelling PET PS HDPE Green dot others PVC Eco-label LDPE PP biodegredable

Chemical recycling (also called feedstock or tertiary recycling) Any type of technology that involves controlled chemical reactions during the recycling process is defined as chemical recycling. p p p unzipping depolymerisation back to monomers, step degradation to low molecular weigh (LMW) products through well-defined chain linkage fissions, chain extension for molecular weight upgrading, pyrolysis with the formation of a complex mixture of gaseous, liquid and solid products, and reactive blending of different polymers. 18

Chemical recycling p The easiest to depolymerise are condensation-type resins (polyester, polyamide (PA), polycarbonate (PC), etc. ). p Technologies for the breakdown of such polymers are: hydrolysis, glycolysis, methanolysis, aminolysis, etc. are already proved, and are viewed as relatively cost-effective. p Depolymerisation of addition-type polymers (styrenics, acrylates, etc. ) is of great interest for monomer recovery by precisely unzipping the bonds p The most difficult materials to chemically recycle are thermosets, because their crosslinked molecules tend to resist chemical attack; in these cases pyrolysis has been successfully carried out 19

Chemical recycling – the main advantages p less need for sorting of raw materials compared to mechanical recycling; p the products of recycling are easily reintroduced into the production cycle, without any problems of market saturation; p chemical recycling preserves more value than combustion; p when the crude products resulting from chemical breakdown can be used without further purification, chemical recycling processes are usually economically attractive, giving rise to a strong driving force for recycling. 20

Chemical recycling – the main disadvantages p when severe conditions are required to destroy the polymer chain, the chemical plants must be built with special high cost materials; p high investment costs; p chemical plants should be sufficiently large to reduce operating costs, but continuous feeding with huge amounts of plastic wastes of constant quality may require too much expensive collection; p monomers and useful oligomers can be obtained only from a limited number of polymers that can undergo selective reactions leading to high yields of valuable products. 21

Ratio between the produced plastic materials and its recycling

PET recycling p p Linear thermoplastic polyester (synthetic fibre, films and moulding material). PET production – two stages production: n Reaction of therephtalic acid with 1, 4 -ethandiol at 150 C to produce dimers and trimers with 2 hydroxyl end groups. n Heating of the mixture to 260 C, PET is formed via polycondensation reaction (Sb 2 O 3 )

Properties of PET Property Thermal expansion coefficient (melt) (/K) 6. 55 x 10 -1 Compressibility (melt) (MPa) 6, 99 x 106 Density (g/cm 3) -Amorphous Crystaline 1. 335 1. 420 Dielectric constant (23° C, 1 k. Hz) Elongation at break (%) Glass transition (°C) - Amorphous Crystaline Melting point (°C) Refractive index (Na light) - Amorphous Crystaline Tensile strength (MPa) Young's modulus (MPa) (extensional) 3. 25 12 -55 67 81 250 -265 1, 576 1. 640 172 1. 41 x 104

p A major application is for carbonated drink bottles because of PET’s excellent gas barrier properties. PET tends to crystallise over time (change in properties that can lead to dimensional changes) p Fibres for textiles p Electrical insulation p Blow moulded parts. p In many applications coploymers of PET are used to provide better properties.

PET can be recycled by all major recycling techniques p Problems: p n n Label adhesives can cause discoloration and loss of clarity During reprocessing any residual moisture can lead to degradation and degradation products cause yellowing and alter the mechanical properties.

ECO CIRCLETM Developed by Teijin Fibers, ECO CIRCLE is a closed-loop recycling system for used polyester products. The system employs the world's first technology for chemical recycling, which chemically decomposes polyester for conversion into new polyester raw materials that offer purity comparable to those derived from petroleum. Teijin cooperates with over 130 registered apparel and sportswear manufacturers worldwide that share a commitment to promote progressive environmental activities for the development and manufacture of recyclable products, as well as collection and recycling of these products at the end of their useful lives. Compared to developing polyester materials from petroleum, this repeatable recycling system reduces energy consumption and carbon dioxide emissions by approximately 80% each. 28

Carpet recycling Tufted carpet: Face yarn (nylon) Primary backing (PP) Adhesive (Ca. CO 3/latex) Secondary backing (PP) Two layers of backing (mostly polypropylene fabrics), joined by calcium carbonate-filled styrene-butadiene latex rubber (SBR), and face fibers (the majority being nylon 6 and nylon 6, 6 textured yarns) tufted into the primary backing. Component mass/area for a typical carpet (glm 2). Total is 2224 g/m 2 29

Carpet recycling the total fiber consumption in carpet industry (2001) was about 1. 4 million tons: nylon 60%, olefin 29%, polyester 10%, and wool 0. 3%. p Among the nylon face fiber, about 40% is nylon 6 and 60% is nylon 6, 6. p The rate of carpet disposal is about 2 -3 million tons per year in the USA, and about 4 -6 million tons per year worldwide. p Nylon generally performs the best among all synthetic fibers as carpet face yarn, but it is also the most expensive. p Typical prices per kg for the plastic resins are: nylon $2. 50, polyester $1. 20, and polypropylene $0. 75. This price list provides a perspective on the economics of recycling as well. p 30

Carpet recycling p Carpet collection involves collecting in individual stations, sending the carpet to a regional warehouse, and then to the processing facilities, p sorting of carpets according to the type of the face fiber, p a melting point indicator is an inexpensive instrument that can identify most fiber types (slow and cannot distinguish between nylon 6, 6 and polyester), p Infrared and Raman spectroscopy are much more effective 31

Carpet recycling – size reduction and separation p the feedstock is cut by a rotary drum fitted with hardened blades against a feeding bed, and the cut material is then moved against a screen with specified openings, p Du. Pont: the size reduction and separation steps of nylon 6, 6 carpet provides a dry mix of 50 -70% nylon, 15 -25% polypropylene and 15 -20% latex. Water is added in the second step, where the shredded fiber is washed and separated using the density differences between fillers, nylon and polypropylene. Two product streams are obtained: one 98% pure nylon and the other 98% pure polypropylene. The recycled nylon is compounded with virgin nylon at a ratio of 1: 3 for making automotive parts. 32

Carpet recycling -separation p A centrifuge system has been developed to separate carpet into nylon, polypropylene and adhesive. n n p In the first stage, a liquid with a 1. 15 g/cm 3 density is used to separate the fibers (nylon and polypropylene) from the adhesive. The second stage, using a liquid with a l. 0 g/cm 3 density for further separates the nylon from the polypropylene. The United Recycling process separate carpet components without first going through a size reduction step n n n clipping the facefibers on loop carpet debonding, in which the carpet is bombarded with a combination of air and steam to loosen the calcium carbonate-filled latex backing the secondary backing then is peeled off mechanically 33

Polyamide 2000 AG process, germany 34

Carpet recycling p Solvent extraction has been used to separate the high-value nylon 6 from carpet waste. After extraction at 135 C for 60 min, nylon 6 is precipitated (yield is 90%). The solvents used include aliphatic alcohols, alkyl phenols and hydrochloric acid p supercritical fluid (SCF) method in a batch process p separation of carpet waste at close to room temperature and moderate pressure: up to 2. 3 wt% nylon is dissolved in an 88 wt% formic acid solution, supercritical CO 2 as an anti-solvent is added to precipitate the nylon out of the solution at a temperature of 40 C and a pressure between 84 and 125 atm 35

Carpet recycling - depolimerisation p p p Nylon 6 (polmerisation of caprolactam) Nylon 6, 6 (polycondensation using two difunctional monomers – adipic acid and hexamethylenediamine HMD). PA are polar and have highly crystalline regions, incorporating hydrogen bonded linear sections, and amorphous sections that impart flexilility. Such structure imarts: n High tensile strenghtr, rigidity, hardness, abresion resistance, low thermal expansion coefficient. 36

Carpet recycling - depolimerisation p The number of C between the amide groups leads to significant differences in the physical and mechanical properties. p A low number of C gives rise to a higher melting point and higher density, but higher water adsorption. A higher number of C provide greater flexibility and impact strength. p The level of crytallinity in nylons can be controlled by the processing conditions. p PAs are resistant to most solvents and is dissolved in conc. acid. 37

Most common polyamides Nylon Structure Systematic name Tm (°C) Nylon 4, 6 -[-NH(CH 2)4 NHCO(CH 2)4 CO-]- n Polytetramethylene adipamide 295 Nylon 6, 6 -[-NH(CH 2)6 NHCO(CH 2)4 CO-]- n Polyhexamethylene adipamide 265 Nylon 6, 9 -[-NH(CH 2)6 NHCO(CH 2)7 CO-]- 205 n Polyhexamethylene azelamide 225 n Polyhexamethylene sebacamide Polyhexamethylene dodecanedioamide 217 Polycaprolactam 215 Nylon 6, 10 Nylon 6, 12 -[-NH(CH 2)6 NHCO(CH 2)8 CO-]- -[-NH(CH 2)6 NHCO(CH 2)10 CO-]- n Nylon 6 -[-NH(CH 2)5 CO-]- Nylon 11 -[-NH(CH 2)10 CO-]- n Poly-11 -aminoundecanoic acid 194 Nylon 12 -[-NH(CH 2)11 CO-]- n Poly-12 -aminoundecanoic acid 179 n 38

Carpet recycling - depolimerisation Nylon 6 can be prepared from an amino acid which contains six carbons, aminocaproic acid: 39

Carpet recycling - depolimerisation De-polymerization of nylon 6, 6 is more complicated than that of nylon 6 because nylon 6, 6 is made from two monomers. adipic acid and hexamethylene diamine(HMDA). Depolymerization of nylon 6, 6 to recover adipic acid and HMDA has been demonstrated but has not been implemented in commercial operation. 40

Carpet recycling – melt procesing p p p Most carpet waste contains two immiscible plastics, nylon and polypropylene. The immiscibility of these two components leads to poor mechanical properties (similar to virgin polystyrene) Recycled material contains 35 -67 wt% nylon, 8 -21 wt% polypropylene, 5 -29 wt% SBR and 10 -40 wt% inorganic filler addition of compatibilizers used of twin screw extruder to accomplish high-intensity mixing of thermoplastic recycled polymers may be used for products in a molding process and as matrices in glass fiber reinforced composites 41

Carpet recycling – waste to energy conversion p p p Incineration may be an option for carpet waste that is beyond the capacity of other viable recovery approaches with advanced technologies and proper management, waste-toenergy conversion can be a viable alternative to landfilling The current challenges for the incineration of polymer waste include further improving the incineration efficiency and reducing the harmful end products in the form of ash and noxious gases Incineration is not suited for recycling, such as carpet with unknown face fibers, or carpet with uncommon compositions. Relatively high fuel value of carpet polymers can reduce the need for other fuels, and the calcium carbonate content becomes raw material for cement. 42

Carpet recycling – use of waste fibres p p p Carpet face yarn and textiles as reinforcement for a composite or laminate Because of the fine diameter of the fibers involved, a low viscosity prepolymer in a water base was used to insure complete coverage of the fibers Adhesives were selected to result a high-modulus and creep resistant material Waste carpet blend is coated with phenolic or urea formaldehyde resins (7. 5 to 20 wt% adhesive solids) Fibers were spray coated and molded in a heated press at 150 to 200 C and 3. 4 MPa 43

Composting • ISO 11721 -1: 2001 (soil exposure), ISO 11721: 2003 standard (climatic chamber, 95 to 100 % relative humidity, 29°C, p. H 4 -7. 5 ) Hydrolysis of β-1, 4 glucosidic bond of cellulose 44

ß-glucosidase Endoglucanase Cellobiohydrolase ß-glucosidase Cellobiohydrolase The enzymatic hydrolysis of cellulose. The sites of attack of β-1, 4 glucosidic bonds of cellulase by endoglucanase, cellobiohydrolase and β-glucosidase 45

Visual and microscopic observations A B 0 days 14 days 28 days Scanning electron micrographs of untreated cotton (A) and antimicrobial treated cotton (B) after 0, 14, and 28 days of soil exposure 46

THANK YOU! 47