Transcript Diapozitiv 1 - Institut de Sostenibilitat — UPC

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

Mankind used some 72 million tons of fibre in 2007, the increase
rate of 7-10%

Per capita consumption of fiber in developed country is up to 40 kg
(in average 11 kg/capita);

Textile recycling industry annually diverts only about 15-30% of the
total post-consumer annual textile waste;

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
Poraba energije


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
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

Transportation by air (131.040
kWh/tone)
Finishing (56.400 kWh/tone)
Washing (46.400 kWh/tone)
Ironing (43.000 kWh/tone)
Garment production (22.800
kWh/tone)
By lories (12.900 kWh/tone)
By trains (8.500 kWh/tone)
Shipping (960 kWh/tone)
140000
130000
120000
110000
leta
100000
ple
90000
kWh/tono

pra
80000
lika
70000
izd
60000
ces
50000
žel
40000
lad
30000
20000
10000
0
6
The waste hierarchy refers to the 3Rs of reduce, reuse and
recycle, which classify waste management strategies according
to their desirability
4Rs: 3Rs + Re-thinking
6Rs: 3Rs + Residual waste
management, Resources and
Regionalism
Pyramid model for textile recycling categories,by quantity.
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Textile recycling
8
Methods of textile recycling:


Second hand clothing
Mechanical recycling

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
Chemical recycling

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Fabrics to fibers (convertion to new products)
Re-melting (extrusion)
hydrolysis,
methanolysis,
aminolysis,
pyrolysis
Composting
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Second hand clothing


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
 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
(fiber2fiber)
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
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13
Re-melting (extrusion)


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,..
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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.

Obviously, increasing the amount of plastics recycled would
appear to be the answer.

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.


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.
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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.
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Chemical recycling

The easiest to depolymerise are condensation-type resins (polyester, polyamide
(PA), polycarbonate (PC), etc.).

Technologies for the breakdown of such polymers are: hydrolysis, glycolysis,
methanolysis, aminolysis, etc. are already proved, and are viewed as relatively
cost-effective.

Depolymerisation of addition-type polymers (styrenics, acrylates, etc.) is of great
interest for monomer recovery by precisely unzipping the bonds

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
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Chemical recycling – the main advantages

less need for sorting of raw materials compared to mechanical
recycling;

the products of recycling are easily reintroduced into the
production cycle, without any problems of market saturation;

chemical recycling preserves more value than combustion;

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.
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Chemical recycling – the main disadvantages

when severe conditions are required to destroy the polymer chain,
the chemical plants must be built with special high cost materials;

high investment costs;

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;

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.
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Ratio between the produced plastic materials and its recycling
PET recycling


Linear thermoplastic polyester (synthetic fibre, films and
moulding material).
PET production – two stages production:
 Reaction of therephtalic acid with 1,4-ethandiol at 150C to
produce dimers and trimers with 2 hydroxyl end groups.
 Heating of the mixture to 260C, PET is formed via
polycondensation reaction (Sb2O3 )
Properties of PET
Property
Thermal expansion coefficient (melt) (/K)
6.55 x 10-1
Compressibility (melt) (MPa)
6,99 x 106
Density (g/cm3) -Amorphous
Crystaline
1.335
1.420
Dielectric constant (23° C, 1 kHz)
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

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)

Fibres for textiles

Electrical insulation

Blow moulded parts.

In many applications coploymers of PET are used to provide
better properties.
PET can be recycled by all
major recycling techniques
 Problems:

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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.
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Carpet recycling
Tufted carpet:
Face yarn (nylon)
Primary backing (PP)
Adhesive (CaCO3/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
(glm2). Total is 2224 g/m2
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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%.
 Among the nylon face fiber, about 40% is nylon 6 and 60% is nylon 6,6.
 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.
 Nylon generally performs the best among all synthetic fibers as carpet
face yarn, but it is also the most expensive.
 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.

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Carpet recycling

Carpet collection involves collecting in individual stations,
sending the carpet to a regional warehouse, and then to the
processing facilities,

sorting of carpets according to the type of the face fiber,

a melting point indicator is an inexpensive instrument that can
identify most fiber types (slow and cannot distinguish between
nylon 6,6 and polyester),

Infrared and Raman spectroscopy are much more effective
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Carpet recycling – size reduction and separation

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,

DuPont: 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.
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Carpet recycling -separation

A centrifuge system has been developed to separate carpet into
nylon, polypropylene and adhesive.
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In the first stage, a liquid with a 1.15 g/cm3 density is used to separate
the fibers (nylon and polypropylene) from the adhesive.
The second stage, using a liquid with a l.0 g/cm3 density for further
separates the nylon from the polypropylene.
The United Recycling process separate carpet components
without first going through a size reduction step


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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
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Polyamide 2000 AG process, germany
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Carpet recycling

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

supercritical fluid (SCF) method in a batch process

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 CO2 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
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Carpet recycling - depolimerisation
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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:

High tensile strenghtr, rigidity, hardness, abresion resistance, low
thermal expansion coefficient.
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Carpet recycling - depolimerisation

The number of C between the amide groups leads to
significant differences in the physical and mechanical
properties.

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.

The level of crytallinity in nylons can be controlled by the
processing conditions.

PAs are resistant to most solvents and is dissolved in conc.
acid.
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Most common polyamides
Nylon
Structure
Systematic name
Tm (°C)
Nylon 4,6
-[-NH(CH2)4NHCO(CH2)4CO-]- n
Polytetramethylene
adipamide
295
Nylon 6,6
-[-NH(CH2)6NHCO(CH2)4CO-]- n
Polyhexamethylene
adipamide
265
Nylon 6,9
-[-NH(CH2)6NHCO(CH2)7CO-]-
205
n
Polyhexamethylene
azelamide
225
n
Polyhexamethylene
sebacamide
Polyhexamethylene
dodecanedioamide
217
Polycaprolactam
215
Nylon 6,10
Nylon 6,12
-[-NH(CH2)6NHCO(CH2)8CO-]-
-[-NH(CH2)6NHCO(CH2)10CO-]-
n
Nylon 6
-[-NH(CH2)5CO-]-
Nylon 11
-[-NH(CH2)10CO-]-
n
Poly-11-aminoundecanoic acid
194
Nylon 12
-[-NH(CH2)11CO-]-
n
Poly-12-aminoundecanoic acid
179
n
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Carpet recycling - depolimerisation
Nylon 6 can be prepared from an amino acid which contains six carbons,
aminocaproic acid:
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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.
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Carpet recycling – melt procesing

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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 the thermoplastic
recycled polymers may be used for products in a molding process
and as matrices in glass fiber reinforced composites
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Carpet recycling – waste to energy conversion

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

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.
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Carpet recycling – use of waste fibres

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
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
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Composting
O
H
H
OH
OH
H
H
O
CH2OH
H H
O
CH2OH
O
H
OH H
H
•ISO 11721-1:2001 (soil exposure), ISO
11721:2003 standard (climatic chamber,
95 to 100 % relative humidity, 29°C, pH 47.5 )
O
+ HOH
H
biocatalyst
OH
H
O
H
OH
H
OH
H
O
CH2OH
Hydrolysis of β-1,4 glucosidic bond of cellulose
H
H
OH HO
CH2OH
O
H
OH H
H
O
H
OH
44
ß-glucosidase
Endoglucanase
Cellobiohydrolase
ß-glucosidase
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
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THANK YOU!
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