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OR 12/2009
Emissions from incineration of
fluoropolymer materials
A literature survey
Sandra Huber, Morten K. Moe, Norbert Schmidbauer,
Georg H. Hansen and Dorte Herzke
OR 12/2009
Emissions from incineration of
fluoropolymer materials
A literature survey
Sandra Huber, Morten K. Moe, Norbert Schmidbauer,
Georg H. Hansen and Dorte Herzke
NILU OR 12/2009
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Contents
Page
Table of content
Contents .................................................................................................................. 1
1 Summary ......................................................................................................... 3
2 Abbreviations .................................................................................................. 5
3 Background and purpose ............................................................................... 7
4 Types of fluoropolymers ................................................................................ 9
4.1 Perfluorinated polymers ............................................................................ 9
4.2 Partially fluorinated polymers ................................................................. 10
4.3 Fluoroelastomers ..................................................................................... 11
4.4 Other fluorine containing polymers ........................................................ 12
4.4.1 Fluorinated Polyurethans ............................................................. 12
4.4.2 Hexafluoroisopropylidene-containing polymers ......................... 13
4.4.3 Polyfluoroacrylates and -methacrylates ...................................... 13
4.4.4 Perfluoropolyethers ..................................................................... 13
4.4.5 Perfluorinated ionomers .............................................................. 14
5 Production and consumption of fluoropolymers ....................................... 14
5.1 Consumption of fluoropolymers ............................................................. 15
5.2 Consumption of fluoroelastomers ........................................................... 17
5.3 Future perspectives .................................................................................. 18
6 Thermal degradation of fluoropolymer materials .................................... 19
6.1 Properties and stability of fluoropolymers .............................................. 19
6.2 Thermal degradation experiments with fluoropolymers ......................... 24
7 Greenhouse potential of fluoropolymer combustion products ................ 31
7.1 Thermal degradation products of fluoropolymers ................................... 31
7.2 Possible contribution of incineration of fluoropolymers to global
warming ................................................................................................... 34
8 Conclusions and evaluation of the need for further studies ..................... 36
8.1 Recommendation on future investigations .............................................. 36
9 References ..................................................................................................... 38
Appendix 1 : Review of the SFT report on PTFE ............................................ 43
Appendix 2; List of Fluoropolymers .................................................................. 49
Appendix 3: List of intermediates produced by Daikin (Daikin
Industries, 2008). .......................................................................................... 55
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1 Summary
This report consists of two parts. (1) An overview of existing commercially
available fluoro-polymer materials and their properties, application area,
production and consumption levels is given, and (2) a review of the existing
scientific literature on the possible formation of greenhouse gases upon fluoro-
polymer incineration and the potential greenhouse effects.
Fluoropolymers are special plastics that are used in a great variety of applications
because of their unique properties. They are used in e.g. cable coating, coated
cookware, sports and extreme weather clothing, food handling and medical
equipment. In 2004, the global consumption of fluoropolymers reached almost
133 000 tons.
Polytetrafluoroethylene (PTFE) is worldwide the most produced and consumed
fluoro-polymer followed by polyvinylfluoride (PVF) and a co-polymer of
tetrafluoroethylene and hexafluoropropylene (PVDF and FEP). Therefore, it is
assumed that these also are the major fluoropolymers to end up in municipal
waste incinerators, with minor contributions from a multitude of other recently
introduced fluoro-polymers and -elastomers.
The literature survey was conducted by using comprehensive and widely
appreciated search engines such as SciFinder, ISI Web of Knowledge, and
PubMed, along with specialized technical books on fluoropolymers. Furthermore,
homepages of fluoropolymer companies were scrutinized on their product range
and applications. The report ”Assessment of information assessable on Teflon and
degradation products of Teflon (CAS 9002-84-0)” was reviewed and updated on
missing and new literature (Tobiesen, 2005).
A considerable amount of scientific literature was found on the thermal stability
and decomposition products of PTFE for temperatures between 400 and 600°C,
the temperature range where PTFE and most other fluoro-polymers start to
degrade. The main degradation products were found to be fluoroalkanes and
alkenes, hydrogen fluoride, oxidation products (epoxides, aldehydes and acids),
and fluoro-polymer particulates in this temperature range.
However, municipal waste incineration is carried out at about 850°C, and to our
best knowledge, any emissions of fluoro-polymer degradation products from
household waste incineration have not been monitored yet. On the laboratory
scale the degradation of fluoro-polymers, primarily PTFE, has been investigated
in the temperature range 700-1050°C, yielding CF4 (PFC-14), CHF3 (HFC-23),
C2F6 (PFC-116), tetrafluoroethene (TFE) and hexafluoropropene (HFP) as major
products. The kind of compounds formed is strongly dependent on the
incineration conditions like temperature, moisture, oxygen content, use of
catalysts etc. Few studies have been published on the incineration degradation
products of other fluoropolymers than PTFE.
The most potent greenhouse gases formed by fluoropolymer incineration are
compounds containing C–F bonds, which absorb electromagnetic radiation in the
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1000-1400 cm-1 range where the atmosphere is rather transparent.
Perfluoropolymers will therefore presumably produce the most efficient
greenhouse gases upon incineration.
Incineration of fluoropolymer containing products has a great potential to
contribute considerably to the total greenhouse gas emissions of Norway, but due
to the lack of sound data on the fate of fluoropolymers in Norway as well as of the
chemical reactions in the different types of MWI plants in Norway, no exact
amounts can be given at this stage. On-site investigations for revealing a realistic
impression on the compounds formed in Norwegian municipal incinerators are
necessary in order to assess the extent and the composition of the organofluorine
emissions. In addition, a quantitative life cycle assessment for the imported PTFE
and other fluoropolymers should be conducted to fill knowledge gaps about the
fate of fluoropolymers in Norway.
The scientists Dr. Sandra Huber, Dr. Morten K. Moe, Dr. Norbert Schmidbauer,
Dr. Georg H. Hansen and Dr. Dorte Herzke contributed to the report.
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2 Abbreviations
1,1,3-TCTFP 1,1,3-TriChloroTriFluoroPropene
1,3-DCTFP 1,3DiChloroTetraFluoroPropene
6F Hexafluoroisopropylidene
BMA Butyl methacrylate
CDFA ChloroDiFluoroAcetic acid
CFC ChloroFluoroCarbon
c-OFB OctaFluoro cyclo-Butane
CPFP ChloroPentaFluorPropene
CPTFE ChloroPolyTriFluoroEthylene
CTFE chlorotrifluoroethylene
CTFE ChloroTriFluoroEthylene
DCFA DiCHloroFluoroAcetic acid
DCHB 1,2-DiChloroHexafluorocycloButane
DFA DiFluoroAcetic acid
E Ethylene
ECTFE co-polymer of ethylene (E) and ChloroTriFluoroEthylene
(CTFE)
EFEP co-polymer of ethylene (E), tetrafluoroethylene (TFE) and
hexafluoropropylene (HFP)
EHA Ethylhexyl acrylate
ETFE co-polymer of Ethylene (E) and TetraFluoroEthylene (TFE),
ethylene tetrafluoroethylene
EVE Esther Vinyl Ether
FDD FluoroDibenzoDioxine
FDF FluoroDibenzoFuran
FEP co-polymer of tetrafluoroethylene (TFE) and
hexafluoropropylene (HFP)
GC-MS Gas Chromatography Mass Spectrometry
GWP Global Warming Potential
HCFC HydroChloroFluoroCarbon
HFC HydroFluoroCarbon
HFIB HexaFluoroIsoButylene
HFIBO HexaFluoroIsoButylene Oxide
HFIFA 1,1,1,3,3,3-hexafluoroisopropyl α-fluoroacetate
HFIMA 1,1,1,3,3,3-hexafluoroisopropyl methacrylate
HFP HexaFluoroPropylene
HFPO HexaFluoroPropylene Oxide
HPFP 1-HydroPentaFluoroPropene
HTE co-polymer of Hexafluoropropylene (HFP),
Tetrafluoroethylene (TFE) and Ethylene
IPCC Inter-governmental Panel on Climate Change
MA Methyl acrylate
MFA MonoFluoroAcetic acid
MFA co-polymer of tetrafluoroethylene (TFA) and
perfluoromethylvinylether (PMVE)
MTFA MethylTriFluoroAcrylate
MW Molecular Weight
MWI Municipal Waste Incinerator
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NIOSH National Institute for Occupational Safety and Health
NMR Nuclear Magnetic Resonance
P Propene
PAVE PerfluoroAlkyl VinylEther
PCTFE Poly ChloroTriFluoroEthylene
PDMS PolyDiMethylSiloxane
PEVE PerfluoroEthyl VinylEther
PFA PerFluoroAlkan
PFA PerFluoroAlkoxy; co-polymer of tetrafluoroethylene (TFE)
and perfluoropropyl vinyl ether (PPVE)
PFA7 Poly-2,2'3,3',4,4',5,5',6,6',7,7',7"-tridecafluoroheptylacrylate
PFMA7 Poly-2,2'3,3',4,4',5,5',6,6',7,7',7"-
tridecafluoroheptylmethacrylate
PFBE PerFluoroButylEthylene
PFCA PerFluoroCarboxylic Acid
PFEPE co-polymer of polytetrafluoroethylene (PTFE) and
tetrafluoroethylene perfluoropropylether
PFIB PerFluoroIsoButene
PFOA PerFluoroOctanoic Acid
PFPE PerFluoroPolyEther
PHFIFA Poly(1,1,1,3,3,3-hexafluoroisopropyl α-fluoroacetate)
PHFIMA Poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate)
PMNFHS PolyMethylNonaFluoroHexylSiloxane
PMTFPS PolyMethylTriFluoroPropylSiloxane
PMVE PerfluoroMethylVinylEther
PPVE PerfluoroPropyl VinylEther
PSEPVE Perfluoro-2-(2-fluoroSulfonylEthoxy) PropylVinylEther
PTFE PolyTetraFluoroEthylene
PTFEMA Poly(2,2,2-trifluoroethyl methacrylate)
PVDF Poly Vinylidene Fluoride
PVF PolyVinyl Fluoride
RF Radiative Forcing
SAR Second Assessment Report
SFT Norwegian Pollution Control Authority
SSB Statistics Norway
TAR Third Assessment Report
TCTFE 1,1,2-TriChloro-1,2,2-TriFluoroEthane
TFA TriFluoroAcetic acid
TFE TetraFluoroEthylene
TFEMA 2,2,2-trifluoroethyl methacrylate
TFEO TetraFluoroEthylene Oxide
TFE-P co-polymer of TetraFluoroEthylene (TFE) and Propylene
TFMAA -(TriFluoroMethyl) Acrylic Acid
TFP 3,3,3-TriFluoroPropylene
TH Time Horizon
THV terpolymer of Tetrafluoroethylene (TFE),
Hexafluoropropylene (HFP) and Vinylidene Fluoride
(VF2/VDF)
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VDF,VF2 Vinylidene Fluoride (1,1-difluoroethylene)
VOC Volatile Organic Compond
XFDA Poly(1H,1H,2H,2H-perfluorodecyl acrylate)
XFDMA Poly(1H,1H,2H,2H-perfluorodecyl methacrylate)
3 Background and purpose
Fluoropolymers are crucial parts of our daily lives, often in invisible ways. They
are special plastics being chemically inert, non-wetting, very slippery, nonstick,
highly fire resistant, high temperature resistant, highly weather resistant and
regarded as nontoxic. Fluoropolymers are used in a multitude of ways as in
cookware and food handling (e.g. bakeries), sports and extreme weather military
clothing, medical equipment, silicon chip and pharmaceutical manufacturing,
motor oil additives, house and car air conditioning, and wiring to laptop
computers, cell phones, aircrafts, fire alarms and data communications, under-
hood in cars and down-hole oil wells, and high temperature filters for coal plants
(Fluoropolymer Division, 2008).
In 2004, the global consumption of fluoropolymers reached almost 133 000 tons
and exceeded a value of $2.5 billion (Fluoropolymer Division, 2008). Will et al.
announced in a marked report that the global trade of fluoropolymers reached
about 60 000 tons, representing 46% of total consumption in 2005. Western
Europe consumed 23 900 tons PTFE, 6 800 tons PVDF and 4 700 tons of other
fluoropolymers in 2005 (Will et al., 2005).
In today‟s society large amounts of disposed products end up as waste.
Incineration is one state of the art method for waste treatment, while landfill is
still the most used. In 2006, 1 889 000 tons of waste were deposited in Norwegian
landfills and 847 000 tons of waste (31% by mass) were incinerated (Table 1)
(http://www.ssb.no/avfhand/).
Additionally, the total amount of waste produced in Norway has been increasing
continuously. Paper (including coated paper and cardboard), plastic and textiles
are the main waste types containing fluoropolymers and other fluorinated organic
compounds, all of them increasing steadily (for more details see:
http://www.ssb.no/avfregno/).
Table 1 Waste amounts in Norway in 2006 in 1 000 tons:
Waste type (2006)
Paper
Plastics
Textiles
Recycling
670
63
13
Biological treatment
-
-
-
Incineration
216
193
64
Landfill
147
123
44
Other treatment
199
91
0
According to the data given by SSB, 17.5% of paper, 41% of plastics and 53% of
disposed textiles were incinerated in 2006 in Norway, summing up to 470 000
tons of potentially fluoropolymer containing waste.
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With the upcoming ban of landfilling biological decomposable waste, an
increasing part of products containing fluoropolymers like coated paper, will end
up in municipal waste incineration (MWI) plants in the future
(http://www.sft.no/artikkel____43096.aspx?cid=10621). However, it is difficult to
estimate an approximately amount of fluoropolymer content in domestic waste
and the subsequent amount fluoropolymers incinerated. A quantitative life-cycle
assessment on the imported fluoropolymers could provide a better estimate for
this. Import and export of waste into and out of Norway occur as well, relying on
waste treatment regulations in the target country. In order to estimate any global
contributions of Norwegian waste incineration to global warming, the whole
picture must be assessed.
During the combustion process the waste undergoes thermal degradation which
results in more and/or less stable degradation products. The previous SFT report
”Assessment of information assessable on Teflon and degradation products of
Teflon (CAS 9002-84-0)” revealed that upon incineration of PTFE, carbonyl
fluoride (COF2), trifluoroacetic acid (TFA), tetrafluoroethene (TFE), and
hydrogen fluoride (HF) are emitted. COF2 is highly toxic and has an atmospheric
half-time of approximately two weeks. HF is a strong inorganic corrosive which
shows a high reactivity with other molecules in the atmosphere as well as a
tendency for wet deposition and particle binding. In addition, other compounds
such as perfluorinated carbons (PFC) can be produced by combustion of
fluoropolymer materials; however, their magnitude and potential to contribute to
global warming, are at present not thoroughly assessed.
The aim of this literature study was to:
1. Review the current state of knowledge on the emission and
formation of greenhouse gases during combustion of
fluoropolymer materials.
i. Critical review and update of SFT report
“Miljøvurdering av miljøinformasjon vedrørende
Teflon og nedbrytningsprodukter fra Teflon (Cas nr
9002-84-0)”.
ii. Theoretical presentation of formation of greenhouse
gases during combustion of other fluoropolymer
materials which are in use besides PTFE.
iii. Conclusion of requirements for further experimental
work regarding this study.
2. If 1.iii. shows that further work related to this study is necessary, a
concept on how to perform controlled in-vitro experiments in the
lab to test whether greenhouse gases are formed during combustion
of fluoropolymer material will be presented. In addition, on-site air
sampling in incineration treatment plants could be of interest. This
concept will also include an approximate estimation of costs
performing the suggested experiments.
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4 Types of fluoropolymers
Fluoropolymers are produced and sold worldwide by several manufacturers and
are essential to a variety of technologies and products. They are a versatile family
of engineering materials, often exhibiting a broader range of applications
compared to nonfluorinated substitutes. Fluoropolymers are among the few plastic
materials that can withstand the temperatures inside ovens and the engine
compartments of aircrafts. They have high resistance to a broad range of fuels,
solvents and corrosive chemicals. These unique properties provide critical
performance characteristics needed to prevent fire, fluid emission, electrical
overloading or similar emergencies in many high performance applications. In
addition, for virtually all of these applications, fluoropolymers are one of the very
few materials that meet system performance needs in high temperature and harsh
chemical environments (The Society of the Plastic Industry, 2005).
Major industries using/applying fluoropolymers and -elastomers are aerospace,
military, automotive, transportation, chemical and petrochemical processing,
semiconductor and electronics manufacturing, telecommunications, power
generation, pollution control and consumer housewares (Fluoropolymer Division,
2008).
Among the fluoropolymer materials four groups can be distinguished: (i)
perfluorinated polymers; (ii) partially (or poly-) fluorinated polymers; (iii)
fluoroelastomers; and (iv) other fluorine containing polymers. All four groups will
be described more closely in the chapters 4.1-4.4 below.
4.1 Perfluorinated polymers
The discovery of polytetrafluoroethylene (PTFE) in 1938 by Roy Plunkett of
DuPont Company started the era of fluoropolymers. In 1950 DuPont
commercialized PTFE as Teflon® (Figure 1). Since then a large number of other
fluorine containing polymers have been developed, primarily in the last three
decades. Some of them are derivatives of the original PTFE and some contain
other elements, such as chlorine, silicon, or nitrogen, and represent a large group
of materials with broad industrial applicability.
Figure 1: 3D model of a section of PTFE and structural formula of PTFE.
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PTFE belongs to the group of perfluorinated polymers and is generally superior to
other fluoropolymers with respect to properties and performances. PTFE is a
polymer consisting of recurring tetrafluoroethylen (TFE) monomer units [CF2-
CF2]n (Figure 1). After heating, the virgin resin forms a clear, coalescable gel at
330°C±15°C. Once produced, the gel point (often referred to as the melting point)
is 10°C lower than that of the virgin resin (Scheirs, 1997). PTFE is sold as a
granular powder, a fine powder, or an aqueous dispersion. In addition, it can be
blended with water or other solvents and sprayed on metals or fabric. Chemical
pipelining, wire insulation, or fuel hose tubing are examples of end products made
from melted polymer, while cookware or roofing material illustrates end uses of
the dispersed product (The Society of the Plastic Industry, 2005).
Other perfluorinated polymers are:
Perfluoroalkanes (PFA) PFA resin is a polymer of TFE and a perfluorinated vinyl
ether having the formula [(CF(ORf)–CF2)x(CF2–CF2)y]n where ORf represents a
C1-C4 perfluoroalkoxy group. PFA melts at ~300°C and is melt processible. It is
available in the form of pellets, powder, and as an aqueous dispersion (The
Society of the Plastic Industry, 2005).
MFA. MFA is a copolymer of TFE and perfluoromethylvinylether (PMVE). MFA
melts at 280-290°C. It is available in the form of translucent pellets and aqueous
dispersions (The Society of the Plastic Industry, 2005).
4.2 Partially fluorinated polymers
Partly fluorinated polymers are:
Ethylene- chlorotrifluoroethylene (ECTFE) is a copolymer having the formula
[(CH2–CH2)x(CFCl–CF2)y]n. ECTFE has a melting point range of 220-245°C and
is melt processible. It is available in the form of translucent pellets and as a fine
powder and is the most important chlorotrifluoroethylene (CTFE) copolymer (The
Society of the Plastic Industry, 2005).
Polychlorotrifluoroethylene (PCTFE) is a polymer of CTFE with the formula
(CF2–CFCl)n. It has a melting point range of 210-220°C and is melt processible. It
is available in pellet, granular and powder form (The Society of the Plastic
Industry, 2005).
Polyvinylidenefluoride (PVDF) is a homopolymer of vinylidene fluoride (VF2)
having the formula (C2H2F2)n or a copolymer of VF2 and hexafluoropropylene
(HFP) having the formula [(CF(CF3)–CF2)x(C2H2F2)y]n. All are sold as PVDF
copolymers. PVDF polymers/copolymers melt at 90°-178°C, are melt processible,
and are supplied in the form of powder, pellets, and dispersions (The Society of
the Plastic Industry, 2005).
Ethylene-tetrafluoroethylene (ETFE) is a copolymer of ethylene and TFE having
the formula [(CF2–CF2)x(CH2–CH2)y]n. ETFE melts above 220°C. It is melt
processible and is supplied in pellet and powder form (The Society of the Plastic
Industry, 2005).
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Ethylene-tetrafluorethylene-hexafluoropropylene (EFEP) is a copolymer of
ethylene, TFE and hexafluoropropylene (HFP) with the formula [(CH2–
CH2)x(CF2–CF2)y(CF(CF3)–CF2)z]n. EFEP polymers melt at 155-200°C, it is melt
processible and is supplied in pellet form (The Society of the Plastic Industry,
2005).
Hexafluoropropylene, tetrafluoroethylene and ethylene copolymer (HTE) is melt
processible with melting points from 155215°C depending on grade. It is available
in pellets of agglomerate form (The Society of the Plastic Industry, 2005).
The terpolymer of TFE, HFP and VF2 (THV) has the formula [(CF2–
CF2)x(CF(CF3)–CF2)y(CH2–CF2)z]n. THV is melt processible with melting points
ranging from 115 to 180°C depending on its grade. It is available in pellet,
agglomerate or as an aqueous dispersion (The Society of the Plastic Industry,
2005).
Melt-processible partially fluorinated copolymers, like FEP, PVDF/PVF,
PFA/MFA, ETFE/ECTFE/PCTFE, or CTFE-VFD, represent a large share of the
fluoropolymer market (Will et al., 2005). A major application is wire and cable
insulation. Injection moldable products such as PFA or MFA are widely used in
high-performance, high purity fluid handling systems, such as those used in
making semiconductor chips.
4.3 Fluoroelastomers
The third major category of fluoropolymers is fluoroelastomers, like VF2,
hexafluoropropylene (HFP) or tetrafluoroethylene (TFE). Fluoroelastomers were
introduced commercially in 1955. As the name implies, fluoroelastomers are
synthetic rubber-like materials. Fluoroelastomers are fluorine-containing
polymers known for their exceptional resistance to heat, weathering, a wide
variety of fluids and chemicals as well as for their excellent sealing and other
mechanical properties. They are used in special performance applications where
extreme temperature ranges and chemical attack are encountered.
The main constraints on the use of fluoroelastomers are costs due to the relatively
complex technology of processing. The products generally have fairly low-
temperature flexibility and low elasticity. The solvent resistance of
fluoroelastomeres is generally high; however, certain organic liquids may cause
considerable swelling. In addition, fluoroelastomers are very sensitive to moisture
and require a strictly controlled processing environment, which makes the
processing of fluoroelastomers difficult.
Common names and producers of some main commercially available
fluoroelastomers are presented in Table 2. Names and producers of some common
fluoroelastomers.Table 2 (Ameduri et al., 2001):
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Table 2. Names and producers of some common fluoroelastomers.
Fluoroelastomer
Producer
Daiel® 801 and 901
Daikin
Fluorel®
3M/ Dyneon
Technoflon®
Ausimont
SKF®-26
Russia
Viton®A and B
DuPont
Fluorinated monomers, which are the starting material to prepare these polymers,
can be divided in two classes: i) VF2-based fluorocarbon elastomers, and ii) TFE-
based fluorocarbon elastomers (perfluoroelastomers).
The most commonly used perfluoroelastomer is perfluoromethylvinylether
(PMVE) due to its favorable polymerization properties. Perfluoroelastomers are
high-performance elastomers with exceptional chemical resistance properties and
high-temperature stability (up to 300°C) and can be used for all applications
where the properties of regular fluoroelastomers are not sufficient.
Viton A, a copolymer of VF2 and HFP containing 68% fluorine, was originally
introduced commercially to the marked in 1958. Viton B, a terpolymer including
TFE, containing 68% fluorine, was introduced shortly after Viton A and provided
a significant improvement in heat and fluid resistance. Today, about 50 years after
the introduction of the first commercial grade, there exist a wide range of
copolymers and terpolymers with fluorine levels as high as 70%.
Perfluoroelastomers are used mainly in high performance O-rings. The major
global producers of fluorocarbon elastomers are DuPont, Dyneon, Solvay Solexis
and Daikin.
4.4 Other fluorine containing polymers
4.4.1 Fluorinated Polyurethans
Polyurethans are perhaps the most versatile polymers. Materials with a wide
variety of physical and chemical properties can be formulated from the many
commercially available and relatively inexpensive polyisocyanates and polyols.
Introducing fluorine into polyurethane resins brings about changes in properties
similar to those seen when other polymers are fluorinated. Chemical, thermal,
hydrolytic, and oxidative stability are enhanced, and the polymer becomes more
permeable to oxygen. Surfaces treated with fluorinated polyurethans are
biocompatible.
Fluorourethans are widely used in modern chemical technology, like in products
ranging from hard, heat-resistant electrical components to biologically compatible
surgical adhesives. The most common use is in surface coatings for industrial and
residential structures, automobiles, ships and aircraft. They are also widely used in
medical products and as surface-enhancing treatments for leather, textiles and
carpets. Properties of a particular fluorourethane are determined by the raw
materials and manufacturing processes used. Useful generalizations about
properties cannot be made without considering the use for which the material is
designed (Scheirs, 1997). Typical applications are surface coatings, surface
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treatments of leather, textile and other substrate, cladding for optical fibers, etc.
(Drobny, 2001).
4.4.2 Hexafluoroisopropylidene-containing polymers
Monomers containing the hexafluoroisopropylidene (6F) group have found
worldwide application in the synthesis of high-performance polymers. These
polymers show dramatic improvement of properties when compared to non-
fluorinated analogues. In general the presence of the 6F group in a polymer
increases solubility, oxidative and thermal stability, optical transparency, flame
resistance and resistance to UV mediated degradation, while decreases
crystallinity, dielectric constant, water absorption and surface energy.
Numerous applications for polymers containing hexafluoroisopropylidene groups
have been suggested, including water and heat resistant coatings, fibers, adhesives
and even dental prostheses. The high cost of these materials, however, limits their
use to small-scale and speciality applications such as microelectronics, aerospace
and medical devices (Scheirs, 1997).
4.4.3 Polyfluoroacrylates and -methacrylates
The earlier progress in supersonic aviation necessitated the need to develop
„organic‟ glasses which exceed the current capabilities of acrylics such as
poly(methylmethacrylate) in terms of heat and impact resistance. Fluoroalkyl α-
fluoroacrylate polymers are characterized by a higher glass transition temperature,
enhanced heat resistance, good mechanical strength and flexibility in comparison
with the widely used fluoroalkyl methacrylate polymers. Polymers and
copolymers of fluoroalkyl acrylates and fluoroalkyl methacrylates have the most
practical use. They are used in the production of plastic lightguides, resists, water-
, oil- and dirt-repellent coatings and in other advanced applications (Scheirs, 1997,
Drobny, 2001). Foraperle® products are fluorinated acrylic copoylmers used for
the treatment of paper, paperboard, and leather (www.dupont.com). The
monomeric components of Foraperle 390 are butyl methacrylate (BMA), 2-
ethylhexyl methacrylate (EHA), and 1H,1H,2H,2H-perfluorodecyl acrylate
(XFDA) (Lazzari, 2009).
4.4.4 Perfluoropolyethers
Perfluoropolyethers (PFPEs) are a class of low molecular weight polymers (500-
15 000 Dalton) that were originally developed in the mid 1960s. Their molecular
structure, comprising only carbon, fluorine and oxygen, makes these materials
useful for applications under extreme conditions, in the presence of aggressive
chemicals and in oxidizing environments. They have approximately the same
chemical stability as PTFE in most cases. PFPEs are liquids at room temperature
with very low volatility and their viscosity shows little temperature dependence.
In addition, they show almost no shear thinning even at very high shear rates.
PFPEs are excellent lubricants. They are produced by a variety of different
polymerizations techniques. The basis repeat units are CF2O, CF2CF2O,
CF2CF2CF2O and CF(CF3)CF2O while the terminal groups of the polymer chain
can be CF3O, C2F5O and C3F7O. The structure depends on the method used for
synthesis.
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Fluorolink, Fomblin, Galden and H-Golden are typical trade names for PFPE
products manufactured by Solvay Solexis; whereas Demnum, Daifloil, Optodyne
Unidyne and Daifree are manufactured by Daikin. Additionally PFPEs are used as
intermediates in polymer synthesis in order to produce polyurethanes, elastomers,
epoxy and polyester resins, stratifying polymers and paint additives (Scheirs,
1997).
4.4.5 Perfluorinated ionomers
This group resins is based on copolymers of TFE and perfluorinated vinyl ether
containing a terminal sulfonyl fluoride group. The commercial products are
available mainly in the membrane form, from DuPont as NAFION membranes
and from Ashai Glass as FLEMION membranes. Major areas of application are in
the field of aqueous electrochemistry. The most important application for
perfluorinated ionomers is as a membrane separator in chloralkali cells. They are
also used in reclamation of heavy metals from plant effluents and in regeneration
of the streams in the plating and metals industry. The resins containing sulfonic
acid have been used as powerful acid catalysts (Drobny, 2001). Appendix 3 lists
various kinds of fluorinated intermediates used and produced during
fluoropolymer production.
Appendix 2 gives an overview over key fluoropolymers, reprocessed PTFE and
melts, filled compounds, concentrates, coatings, and fluoroelastomers, plus the
material suppliers and their trademarks.
5 Production and consumption of fluoropolymers
In 2004, the world consumption of fluoropolymers reached almost 133 000 tons
and exceeded a value of $2.5 billion (Figure 2).
Figure 2: Global market demand of fluoropolymers in the year 2004
(Fluoropolymer Division, 2008). ROW: rest of the world.
Western Europe consumed in 2004 23 900 tons PTFE, 6 800 tons PVDF and
4 000 tons of other fluoropolymers (Will et al., 2005). An overview over the
worldwide distribution pattern of the different fluoropolymers is shown in Figure
3.
ROW
Japan
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Figure 3: World consumption of Fluoropolymers in 2004 (Will et al., 2005).
By summing up all types of consumed fluoropolymers 34 700 tons were
consumed in Western Europe in 2004. That is a consumption of fluoropolymers of
0.09 kg/capita (for a population of 370 million in Western Europe). By using a
population of 4.7 million people in Norway as a calculation basis, the theoretical
Norwegian consumption of fluoropolymers in 2004 was roughly 441 tons.
However, the Substances in Preparations In the Nordic countries (SPIN) database
reported the use of only 1.7 tons of PTFE in Norway in 2006 in chemical products
and preparations, compared to 292 tons for Sweden. The consumption of
fluoropolymers is still increasing worldwide, so the Norwegian consumption is
expected to have increased accordingly.
According to Ring et al. there have never been any fluoropolymer manufacturing
sites in Scandinavia. Western European production sites are based in France,
Germany, Italy, Netherlands and UK with total capacity of 46 800 tons in 2007
(Ring et al., 2002). US production in 2007 was higher at 158 200 tons including
all fluoropolymer types. In the last years other parts of the world have become
quite important. Japan produced 35 800 tons and China is an especially important
expanding market. The entire rest of the world (excluding Western Europe, US
and Japan) produced 25 700 tons in 2007 with China/South Korea/Taiwan
contributing with 19 300 tons (Will et al., 2005).
5.1 Consumption of fluoropolymers
PTFE
The total PTFE market in the USA and Canada was approximately 24 600 tons in
1999. The various forms of PTFE and their respective market shares and market
sector breakdowns are listed in Table 3.
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Table 3: Various forms of PTFE, their respective market shares and market sector
breakdowns in 1999 (Scheirs, 2001). Tpa: tons per annum.
Market Share of the various forms of PTFE (approximately 24 600 tpa)
Granular resins
33% (8 200-10 000 tpa)
Chemical processing
38%
Mechanical
38%
Electrical
12%
Semiconductor manufacture
8%
Laminates
3%
Other
1%
Fine powders
26% (6 400-7 000 tpa)
Textile laminates
26%
Wire and Cable
23%
Tubing
22%
Automotive
21%
Other
8%
Aqueous dispersions
22% (5 400-6 000 tpa)
Consumer and industrial coatings
28%
Coated fiberglass and fabrics
25%
Fibres
17%
Printed circuit boards
14%
Imprgnated items
13%
Antidusting and others
3%
Micronized powders
19% (4 600-4 800 tpa)
Ink and coating
60%
Plastics
35%
Grease and lubricant
3%
Others (e.g. rubbers)
2%
FEP
The annual US consumption of the copolymer of tetrafluorethylene and
hexafluoropropylene (FEP) was approximately 15 000 tons per year in 1999
(Scheirs, 2001), making the FEP the second most important fluoropolymer after
PTFE. The three main markets for FEP resins are wire and cable insulation, tube
and film, and lining applications for pipes, valves and chemical storage tanks
(Table 4).
Table 4: Market sector breakdown for FEP in 2000 (Scheirs, 2001).
Total
15000 tons
Wire and Cable
80%
Tube and film
10%
Lining application
6%
Others
4%
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PVDF
The third most consumed fluoropolymer in the USA is PVDF with an annual
consumption of approximately 9 500 tons. The main markets for PVDF resins
(Table 5) are architectural coatings on buildings, chemical process industry
equipment, molded/extruded products such as tanks, pipes, etc., for semiconductor
manufacture and wire and cable insulation (Scheirs, 2001).
Table 5: Market Sector breakdown for PDVF in 2000 (Scheirs, 2001).
Total
9500 tons
Architectural coatings
40%
CPI/semiconductor manufacture
40%
Wire and cable insulation
20%
ETFE, PFA and ECTFE are only minor fluoropolymers with a consumption
between 2 300 and 2 000 tons per year.
More information on production and consumption levels of fluoropolymers also
can be found in the Marketing Research Report of Will et al., 2005 or in Parker,
2006.
5.2 Consumption of fluoroelastomers
Perfluoroelastomers represent a production of only a few thousand kilograms a
year. However, they are growing at a fast pace in terms of applications and
introduction of new composition to meet industrial needs. They represent less than
1% of the total fluoroelastomer field, dominated by VDF-base copolymers
(Ameduri et al., 2001). More detailed information on world production and
consumption of fluoroelastomers can be found in the Marketing Research Report
of Inoguchi et al., 2006.
North America is the dominant producer and consumer of fluoroelastomers,
followed by Western Europe, Japan and the remainder of Asia (Table 6).
Table 6: Consumption of fluoroelastomers per region in 1998 (Scheirs, 2001)
Region
Consumption (tons)
USA and Canada
21 000
EU
15 000
Japan/Asia
4 000
Inoguchi estimated a global demand for fluoroelastomers of 23 000 tons in 2006,
with a market value estimated at about $1.3 billion. This is half of the PTFE
marked value. The United States, Western Europe and Asia accounted for 99% of
world consumption of fluoroelastomers in 2006 (Inoguchi et al., 2006).
The automotive industry is by far the largest consumer of fluoroelastomers (Table
7) with applications including O-rings, valve stem seals, shaft seals, and extrusion
for fuel hosing and tubing. (Scheirs, 2001).
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Table 7: Fluoroelastomer consumption by industry sector in 2000 (Scheirs, 2001)
Fluoroelastomer consumer
Share
Automotive
65%
Mechanical
15%
Chemical process industry
10%
Aerospace
7%
Other
3%
5.3 Future perspectives
From 2004 to 2009, the average annual increase in world consumption of PTFE
will be approximately 6.0% per year while for other fluoropolymers the increase
will average about 5.3% per year (Will et al., 2005). As emerging design trends
increasingly require superior performance characteristics, fluoropolymers will
continue to replace other materials in demanding applications that justify their
generally higher costs.
Among major fluoropolymer types, fastest growth is expected for PVDF resins, as
strong nonresidential construction will boost demand for PVDF-based
architectural coatings. Gains in demand for FEP will be driven by an improved
market for wire and cable, where FEP is used as a jacketing and insulation
material. Demand for fluoroelastomers will benefit from an improved motor
vehicle output and a revived aerospace market. The most rapid gains for
fluoropolymers will be found in smaller-volume resins, which include a number
of high value products used in fast-growing applications. For example, a strong
semiconductor market will increase the demand for PFA polymers, which are
used in microelectronics processing equipment. Double-digit growth in solar
energy products will fuel gains for PVF films used in the production of
photovoltaic modules. Also, the demand for perfluorosulfonic acid polymers
(such as DuPont‟s NAFION) will be driven by a rapid rise in fuel cell shipments.
Electrical and electronic products are expected to be the largest and fastest
growing market for fluoropolymers through 2011, accounting for 37 percent of
total demand by value. Gains will be driven by a robust turnaround in the wire and
cable market, continued increases in semiconductor shipments and double-digit
growth in fuel cell spending. Transportation applications will benefit from
increasing motor vehicle production, although cost-cutting measures by
automotive producers will restrain the demand for costly fluoropolymer resins.
Industrial equipment markets for fluoropolymers will advance at the slowest pace,
due in part to weakness in the chemical processing industry. However, value gains
will be limited by heightened competition from low-cost foreign imports,
especially commodity PTFE resins from Russia and China (Freedonia, 2007).
The global trend shows that fluoropolymer use is increasing (OECD report, 2007).
Further and more detailed information about the estimated future demands can be
found in Freedonia, 2007.
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6 Thermal degradation of fluoropolymer materials
One of the main questions in this report is whether fluoropolymer combustion
may produce greenhouse gases. To assess this, an overview over the literature
data on the formation of fluoropolymer combustion products is presented.
Definition of thermal processes: Pyrolysis is formally defined as chemical
decomposition of organic materials by heating in the absence of oxygen or any
other reagents, except possibly steam. Thermolysis is a chemical reaction whereby
a chemical substance breaks up into at least two chemical substances when
heated. Combustion (or burning) is a complex sequence of exothermic chemical
reactions between a substance (the fuel) and a gas (the oxidizer) to release heat or
heat and light in the form of either a glow or flames. Combustion normally occurs
in contact with oxygen. Incineration is the process of destroying something
through fire.
Although fluoropolymers are among the most thermally stable plastics, they will
start to generate toxic air contaminants at, or slightly above, their recommended
processing temperatures. Manufacturers recommend the use of local exhaust
ventilation during processing operations because of this property. The rate of
formation rises as temperatures increase and may cause sufficient degradation of
the polymer to produce particulate fume as well as toxic gaseous by-products (The
Society of the Plastic Industry, 2005).
Temperature, availability of oxygen, the physical form of the product and the
residence time at elevated temperature and whether a catalyst is present, are some
of the factors determining the ultimate nature and amount of the decomposition
products.
The four main types of decomposition products formed are fluoroalkanes (among
these PFCs), hydrogen fluoride (HF), oxidation products, and fluoropolymer
particle matter. The presence of other monomers or additives in the fluoropolymer
resin may change the nature of the decomposition product (The Society of the
Plastic Industry, 2005).
6.1 Properties and stability of fluoropolymers
Various fluoropolymers possess different physical and chemical properties. Table
8 displays melting temperature, typical continuous use temperature and processing
temperature for some polymers (The Society of the Plastic Industry, 2005). In
table 7, fluoropolymers and their main decomposition products at defined
temperatures are listed in the order of decreasing stability. The order
ETFE<FEP<PFA<PTFE was confirmed by experiments published by The Society
of the Plastic Industry, 2005. For example, PTFE will endure 2.3 years at 260 ºC
until failure due to degradation (Ellis et al., 2001). Generally, the polymers should
not be exposed to elevated temperatures as they will start an accelerating
decomposition when exposed to conditions above their recommended processing
temperature.
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Table 8. Typical melting points, continuous use and processing temperatures of
polymers (The Society of the Plastic Industry, 2005).
Polymer
Typical melting
temperature (ºC)
Typical continuous use
temperature (ºC)
Typical processing
temperature (ºC)
PTFE
330
260
380
PFA
305
260
380
MFA
280
249
360
FEP
260
205
360
ETFE
220-270
150
310
ECTFE
230
140-150
280-310
THV
120-230
70-130
171-310
TEH
160-210
105-150
200-290
EFEP
158-195
100-150
220-260
PCTFE
215
120
265
PVDF
170
150
232
PVDF copolymer
115-170
100-150
232-249
PTFE. PTFE is extremely inert and stable up to 250ºC. Above this temperature, it
decomposes very slowly, with a reported weight loss of 0.004%/h at 371ºC.
Processing of PTFE above 400ºC is not recommended. The inhalation of PTFE
fumes may cause “polymer fume fever” (Drobny, 2001). Depropagation
(unzipping) to form monomer competes with chain radical transfer reactions, and
the dominant pathway depends on the structure of the fluoropolymer. The high
bond strength of the C–F bond makes depolymerization the dominant mechanism.
In partially fluorinated fluoropolymers, on the other hand, the lower bond energies
of C–H and C–Cl bonds increase the likelihood of chain transfer reactions
(Scheirs, 1997).
FEP. FEP is considerably less thermally stable than PTFE and starts to degrade at
temperatures above 200ºC (Drobny, 2001; Scheirs, 1997). There are two stages in
the degradation of FEP (Drobny, 2001). The first involves the preferential
elimination of HFP from the backbone at a rate four times faster than
depolymerization of PTFE. In the second step the remaining backbone undergoes
decomposition at the same rate as PTFE (Drobny, 2001; Scheirs, 1997).
PFA. PFA is more stable than FEP because of the presence of stable ether groups
in the side chain which serves as a spacer and eliminates steric strain at the
branching point (Scheirs, 1997). However, PFA (e.g. Teflon PFA 340) can
degrade during the processing or use at high temperatures due to the presence of
reactive end groups (e.g., –COF and –CH2OH). The result is cross-linking
reactions and an increase in the molecular weight distribution (MWD) when the
unstable end groups decompose to form radicals, which then undergo radical
recombination reactions (Drobny, 2001; Scheirs, 1997). PFA resins can be
processed at temperatures up to 445ºC (Drobny, 2001).
PVDF. PVDF is considerably less thermally stable than PTFE but much more
stable than PVF or PCTFE (Drobny, 2001; Scheirs, 1997).. Certain inorganic
compounds (SiO2, TiO2, Sb2O3, often used as additives) can catalyze its
decomposition at temperatures above 375ºC (Drobny, 2001; Scheirs, 1997).
ETFE. ETFE degradation is autocatalytic and similar to that of PVDF and is
accompanied by the evolution of HF. Iron and transition metal salts can accelerate
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the degradation of ETFE by dehydrofluorination and oligomers formation
(Drobny, 2001; Scheirs, 1997). Cu salts have been found to stabilize the polymer.
ETFE decomposes readily at temperatures above 380ºC (Drobny, 2001).
Crosslinked ETFE insulation turns yellow after just a few days at 220ºC, and after
two months‟ ageing the insulation had turned brown. The oxidative stability of
ETFE has been related to the oxidative degradation of tandem ethylene linkages.
For example –CF2–CH2–CH2–CH2–CH2–CF2– is less oxidative stable than –CF2–
CF2–CH2–CH2–CF2–CF2– because the shielding effect provided by the fluorine
atoms does not extend over more than one C–C bond length so that the methylene
groups near the centre of the tetramethylene sequence have almost the same
susceptibility to oxidative attack as those in polyethylene (Scheirs, 1997).
PVF. PVF decomposes in air at temperatures above 350ºC by dehydrofluorination
(Drobny, 2001). Unlike PTFE, the fluorine deficient PVF does not yield
appreciable amounts of monomer during pyrolysis. Instead, HF is the major
product of PVF thermal degradation, and it occurs at 350ºC (Scheirs, 1997). At
approximately 450ºC backbone cleavage occurs (Drobny, 2001). Benzene is also
a major degradation product of PVF and is formed by chain scission and
subsequent cyclization (Scheirs, 1997). PVF films discolor at high temperatures,
but retain considerable strength after heat-aging at 217ºC (Drobny, 2001; Scheirs,
1997).
ECTFE. ECTFE has a thermal stability comparable to ETFE and can be
stabilized by the addition of an ionomer, which considerably reduces
dehydrofluorination and dehydrochlorination reactions and suppress the
discoloration of the polymer (Drobny, 2001).
PCTFE. PCTFE can start to degrade at temperatures as low as 250ºC. The
mechanism of thermal degradation of PCTFE is a chain scission and leads to
terminal unsaturation (Drobny, 2001; Scheirs, 1997).
Fluoroelastomers. Fluoroelastomers, such as Kalrez (copolymer of TFE and
PMVE), can maintain their thermal stability to temperatures as high as 300ºC or
even higher, with a maximum continuous service temperature of 315ºC.
Moreover, instead of hardening, the elastomer becomes more elastic with aging
(Drobny, 2001).
Fluorocarbon elastomers. Fluorocarbon elastomers, such as copolymers of VDF
and HFP, typically have a maximum continuous service temperature of 215ºC.
Some metal oxides may cause dehydrofluorination at a temperature of 150ºC or
even lower. Copolymers of VDF and CTFE (e.g., Kel-F) have a maximum long-
term service temperature of 200ºC. Fluorocarbon elastomers based on copolymers
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of VDF/HPFP (hydropentafluoropropylene) and terpolymers of VDF/HPFP/TFE
have lower thermal stability than copolymers of VDF/HFP because they have a
lower fluorine content than the latter (Drobny, 2001).
Table 9: List of fluoropolymers and their main decomposition products at defined
temperatures found in the literature. In parenthesis: PFC-code
Polymer
Temperature
Main products
Reference
PTFE
450°C
COF2
HF
(The Society of the Plastic Industry,
2005)
400-500°C
TFE
HFP
PFIB
(Waritz, 1975)
500°C
HFP
TFA
(Ellis et al., 2001)
530°C
CF4 (PFC-14)
C2F6 (PFC-116)
TFE
HFP
c-C4F8 (c-OFB) (PFC-318)
(Chen et al., 1991)
550°C#
CF2O
C6F2
CF3CFO
C5F4
CF3CF2CFO
(CF2)3O2
(Kitahara, 2009)
600-700°C
TFE
c-C4F8 (c-OFB) (PFC-318)
(Bhadury et al., 2007)
750-800°C
HFP
(Bhadury et al., 2007)
850-900°C
PFIB
(Bhadury et al., 2007)
800°C
CF4 (PFC-14)
(The Society of the Plastic Industry,
2005)
>900°C
C2F6 (PFC-116)
(The Society of the Plastic Industry,
2005)
850°C
HFP
TFE
(Garcia et al., 2007)
750-1050°C
C2F6 (PFC-116)
CF4 (PFC-14)
(Garcia et al., 2007)
ETFE
350°C
COF2
PFBE
TFE
CO
(The Society of the Plastic Industry,
2005)
ECTFE
500°C
TFA
CDFA
(Ellis et al., 2001)
FEP
400°C
COF2
CHF3 (HFC-23)
HFP
TFE
PFIB
(The Society of the Plastic Industry,
2005)
PFA
400°C
COF2
(The Society of the Plastic Industry,
2005)
PFEPE
500°C
TFA
(Ellis et al., 2001)
CPTFE/
PCTFE
500°C
CPFP
CDFA
(Ellis et al., 2001)
PTFE/PFA +
PTFE/FEP
800°C
CH4
CHF3 (HFC-23)
C2F6 (PFC-116)
(Clarke et al., 1992)
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Polymer
Temperature
Main products
Reference
TFE
HFP
PTFEMA
600°C
TFEMA§
(Lazzari et al., 2009)
PHFIFA
600°C
HFIFA§
(Lazzari et al., 2009)
PHFIMA
600°C
HFIMA§
(Lazzari et al., 2009)
TFEMA/MA
600°C
TFEMA§
MA
(Lazzari et al., 2009)
XFDA/BMA
600°C
Butane
BMA
1H,1H,2H-perfluorodecene§
XFDA§
(Lazzari et al., 2009)
XDFMA/EHA
600°C
1H,1H,2H-perfluorodecene§
2-ethylhexene
2-ethylhexanol
XFDMA§
EHA
(Lazzari et al., 2009)
XDFMA/EMA/MA
600°C
MA
1H,1H,2H-perfluorodecene§
EMA
1H,1H,2H,2H-perfluorodecanol§
XFDMA
(Lazzari et al., 2009)
Foraperle* a
fluorinated acrylic
copoylmer.
600°C
CO2
Butene
Butyl methacrylate
2-ethylhexene
2-ethylhexanol
2-ethylhexyl methacrylate
1H,1H,2H-perfluorodecene
1H,1H,2H,2H-perfluorodecanol
1H,1H,2H,2H-perfluorodecyl acrylate
1H,1H,2H,2H-perfluorodecyl methacrylate
1H,2H,2H-perfluorodecanal
(Lazzari et al., 2009)
PFA7
650°C
Monomer
Fluorinated alcohol
Perfluorocyclohexane C6F12
Light products
(Zuev, 2006)
PFMA7
650°C
Monomer
Light products
(Zuev, 2006)
# Oxidative pyrolysis, i.e. pyrolysis in air.
* The composition is not known.
§ Identified through direct interpretation of mass spectra since commercially available electronic
libraries did not include these compounds
Light products include CO2, H2O, C2F4, C2F2H2.
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6.2 Thermal degradation experiments with fluoropolymers
The thermal stability and degradation properties of PTFE have been in the focus
of the scientific community and the consumers for a long time. The temperature
range where thermal degradation of fluoropolymers starts, was the most
investigated endpoint. Only few studies focused on conditions relevant for waste
incineration in Norway (temperatures at 850°C) and they will be discussed first.
Additionally, the results are not always comparable due to different experimental
set-up parameters, e.g., temperature, availability of oxygen, the physical form of
the article, and the residence time at the elevated temperature, making the drawing
of a final conclusions challenging.
Experiments between 800 and 1000°C
Bhadury et al. conducted a series of experiments where PTFE powder underwent
flash pyrolysis under inert atmosphere (N2) in a quartz assembly (Figure 4a). The
experimental set up is attractive for future investigations of PTFE pyrolysis
products. TFE and c-OFB were most abundant at 600-700ºC (Figure 4b), HFP at
750-800ºC, perfluoroisobutylene (PFIB) at 850-900ºC, and hexafluoroethane at
temperatures above 950ºC (Bhadury et al., 2007). The emitted compounds were
identified by both GC-MS and 19F NMR.
Figure 4: (a) Pyrolysis assembly. A: inlet for Nitrogen; B: stoppers; C:
thermocouple; D: inlet for sample; E: filter with glass wool; F: outlet
for gas sampling through tedlar bag. The dashed line indicates oven
interior. (b) Generation of organofluorine compounds by flash pyrolysis
of PTFE (Bhadury et al., 2007).
In the work of Garcia et al., the influence of the temperature as well as the
reaction atmosphere on the products obtained in the thermal degradation of PTFE
was evaluated. At 850 °C, pyrolysis of PTFE leads to extensive formation of
hexafluoropropylene (HFP; 82%), although a significant yield of
tetrafluoroethylene (TFE) was also obtained (12%). At fuel-rich combustion
(oxygen supply) conditions at temperatures between 750 and 1050 °C, the main
fluorine products are C2F6 (PFC-116) and CF4 (PFC-14). 27 minor products,
including long chain hydrocarbons (C14-C20), organic acids (C8-C16), alcohols, and
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toluene were identified in the pyrolysis and combustion of PTFE. The formation
of fluorinated compounds is highest at 750 and 850 °C and decreases at 950 and
1050 °C (Garcia et al., 2007). However, differences in the process parameters
such as temperature, operation atmosphere and secondary reactions can lead to a
quite different spectrum of the major degradation products.
A mechanism for the formation of unsaturated compounds under non-oxidative
condition with further reaction of the primary combustion products by the
introduction of oxygen is given in Figure 5.
PTFE
Pyrolysis
C2F4, C3F6
3 C2F42 C3F6
Combustion
C2F4 + O2
C3F6 + O2
2 C2F6 + O2
CF4 + CO2
C2F6 + CO2
3 CF4 + CO2
Figure 5: Proposed reaction mechanism for the thermal degradation of PTFE
(Garcia et al., 2007).
In a full scale fire experiment with telecommunication cables insulated and
jacketed with fluorinated materials (Teflon® FEP and/or Teflon® PFA) at 850 °C,
Clarke et al. identified CF4 (PFC-14), CHF3 (HFC-23), C2F6 (PFC-116), TFE,
HFP, and small amounts of four carbon species as the most abundant compounds,
which is in accordance with the findings of Garcia et al. (Clarke et al., 1992).
In Clarke‟s experiments, the formation of a maximum of 8.4 g CF4 and 68 g C2F6
from 100g PTFE was achieved at 850 °C. Similarly, Garcia reports 5.5 g CF4 and
61 g C2F6 for the same temperature and per PTFE amount. When run at 1050 °C,
9.3 g CF4 and 12.5 g C2F6 are formed according to Garcia et al (2007). Since these
are the only available quantitative data described in the literature so far, taking
relevant temperature conditions in MWI into consideration (e.g. 850 °C and
above), any assessment concerning emissions of PFCs in Norwegian waste
incinerators conditions must rely on theses data until more appropriate data are
available. The topic is further discussed in Chapter 7.
In addition to the degradation products mentioned above, Herzke (1998) identified
several fluoro-dioxins and fluoro-benzofurans, besides other fluorinated aromatic
compounds upon PTFE thermolysis (≤ 800°C), see Figure 6 for structures.
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Figure 6. Fluorinated dioxins and benzofurans formed upon thermolysis of
fluoropolymers Herzke (1998).
Experiments between 300 and 800°C
The National Institute for Occupational Safety and Health, USA, (NIOSH)
suggested in its 1977 Criteria Document for PTFE that the TFE monomer is the
principle gaseous product at temperatures that just produce softening or melting of
the polymer (330ºC). The TFE may be a residual monomer that is trapped in the
resin particles or evolved as the resin structure changes with temperature (The
Society of the Plastic Industry, 2005). As the PTFE temperature increases to
approximately 450ºC in air, carbonyl fluoride and hydrogen fluoride become the
main decomposition products. Carbonyl fluoride hydrolyses in the presence of
moist air to HF and carbon dioxide. Small amounts of HFP may also be found at
450°C. The highly toxic chemical, perfluoroisobutylene (PFIB), has been detected
as a minor decomposition product at temperatures above 475ºC. When the
temperature reaches approximately 800ºC, tetrafluoromethane (CF4) begins to
form (The Society of the Plastic Industry, 2005).
In a weight loss experiment, PTFE was heated to 400-500ºC, and the emitted
gases were monitored by GC-MS (Waritz, 1975). In this temperature region, TFE,
HFP and PFIB were the most abundant thermolysis products (Figure 7).
Figure 7: Evolution of (O) tetrafluoroethylene, (O) hexafluoropropylene, and (O)
perfluoroisobutylene from polytetrafluoroethylene resin as a function of
temperature (Waritz, 1975).
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Kitahara et al. (2009) conducted oxidative pyrolysis of PTFE at 550°C and
identified CF2O (100), C6F2 (10), CF3CFO (21), C5F4 (5), CF3CF2CFO (2), and
(CF2)3O2. The relative intensities are given in parentheses.
DuPont conducted a weight loss experiment of six fluoropolymer resins. The
resins were heated for 1-24 h (The Society of the Plastic Industry, 2005), results
are presented in Table 8 (The Society of the Plastic Industry, 2005). Formation of
PFIB, even in small amounts, is noted because of its high toxicity (2 h LC50 for
rats is 1 ppm). PFIB was formed from FEB at 400ºC, whereas 525ºC was required
to produce PFIB from PTFE. This difference is presumably due to the branched
chain of FEB (Baker, 1993; The Society of the Plastic Industry, 2005). These
experiments also indicate the following thermal stability:
ETFE<FEP<PFA<PTFE.
Table 10: Comparison of one hour thermogravimetry (TGA) weight loss with
weight of evolved gases. Weight of evolved gases as % of sample of
evolved gases as % of sample. HFP is hexafluoropropylene and PFBE
is perfluorobutylethylene (Baker, 1993; The Society of the Plastic
Industry, 2005).
Resin
Temp
ºC
TGA%
wt. loss
PFIB
TFE
HFP
HCF3
PFBE
COF2
CO
ETFE 200
350
5.3
n.d.
0.06
n.d.
n.d.
0.3
2.5
0.06
FEP 100
400
2.5
0.003
0.06
0.38
0.19
n.d.
1.2
n.d.
PFA 340
400
0.43
n.d.
n.d.
n.d.
n.d.
n.d.
0.53
n.d.
PFA 440
400
0.26
n.d.
n.d.
n.d.
n.d.
n.d.
1.2
n.d.
Yamada et al. investigated the fate of a fluorotelomer-based polymer under
incineration conditions to determine whether perfluorooctanoic acid (PFOA) is
formed as a thermal degradation product. The main aim was to investigate the
thermal degradation of a fabric treated with a fluorotelomer-based acrylic polymer
under laboratory conditions conservatively representing typical combustion
conditions of time, temperature, and excess air level in a municipal incinerator.
Thermal testing was initiated at 600 °C. The decomposition of the „„Telomer‟‟
(CF2n+1CH2CH2–X) functionality resulted in the formation of compounds
containing the •CF2CH-CH2 fragment in greater amounts with increasing
temperature. Additionally, the authors report that the combustion tests of the
treated and untreated article at 1000°C showed no detectable levels of PFOA
(Yamada et al., 2005).
Ellis et al. characterized the structures of compounds released upon thermolysis
(up to 500°C) of different fluoropolymers. From all the polymers investigated, C2-
C14 perfluorocarboxylic acids and [per]chlorofluoro-carboxylic acids and their
terminal –OCF3 ethers were observed, along with the low molecular weight
compounds dichlorofluoro acetic acid (DCFA), chlorodifluoroacetic acid
(CDFA), difluoroacietic acid (DFA), monofluoroacetic acid (MFA), HFP,
chloropentafluoropropene (CPFP), and fluoroformaldehyde (F2C=O) (Ellis et al.,
2003).
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Lazzari and colleagues (2009) subjected the partially fluorinated methacrylic
polymer Foraperle 390 to 600°C for ten seconds, and 11 major product were
identified. The non-fluorinated degradation products were CO2, butene, butyl
methacrylate, 2-ethylhexene, 2-ethylhexanol, and 2-ethylhexyl methacrylate. The
fluorinated products were 1H,1H,2H-perfluorodecene, 1H,1H,2H,2H-
perfluorodecanol, 1H,1H,2H,2H-perfluorodecyl acrylate, 1H,1H,2H,2H-
perfluorodecyl methacrylate, and 1H,2H,2H-perfluorodecanal.
Thermolysis of the fluorinated side chain acrylic polymers Poly-
2,2'3,3',4,4',5,5',6,6',7,7',7"-tridecafluoroheptylacrylate (PFA7) and Poly-
2,2'3,3',4,4',5,5',6,6',7,7',7"-tridecafluoroheptylmethacrylate (PFMA7) at 550 and
650°C was reported by Zuev et al. (Zuev, 2006). The major products were the
monomer, and ”alcohol” and perfluorocyclohexane (C6F12). Light products, such
as CO2, H2O, C2F4, and C2F2H2. There was observed a shift towards lighter
products at increased temperature.
TFE, HFP and cyclo-octafluorobutane (c-OFB) were the main gases produced
upon thermolysis of the pure fluorinated polymer and of the commercially
available products tested (Table 9). TFA and CDFA were the main acids to be
observed in the thermolysis of fluoro- and chlorofluouro-polymers, while other
longer-chain perhalogenated acids were also identified. A mechanism for the
formation of TFA caused by thermal degradation of PTFE at 500°C, is given in
Figure Figure 8: Proposed reaction mechanisms involved in the thermolysis of a
fluoropolymer. The explicit major pathways for the production of TFA are shown.
As indicated by the bold arrow, the most significant step in the thermal
decomposition is the formation of carbine radicals. These radicals then react with
constituents present in the air, oxygen and trace amounts of water, to form
perfluorinated acids (n=0-12, m=1-7), the yield being inversely proportional to the
number of carbon atoms in the chain. The distribution of product yield depends on
temperature and the composition of the atmosphere. A Δ indicates heat. (Ellis et
al., 2001).Figure 8. The mechanism is supported by key products observed by
several other studies and the additional products observed in this investigation. It
is hypothesized that the thermolysis of PTFE and other polyfluorinated polymers
is a major contributor to the steadily increased measured concentrations of TFA in
urban environment precipitation. The other products formed upon thermolysis of
such polymers, PFCA, F3CO-PFCA and PFA may contribute to global warming,
as discussed below. The global warming potential of TFA is unknown.
NILU OR 12/2009
29
Table 11: Identified products identified upon thermolysis of fluoro- and
chlorofluoro-polymers at up to 500°C. A dash indicates that the analyte
was positively identified but not quantified. PTFE:
polytetrafluoroethylene (Teflon); CPTFE: chloro-polytrifluoroethylene
(Kel-F); ECTFE: ethylene-chlorotrifluoroethylene; PFEPE:
polytetrafluoroethylene-co-tetrafluoroethylene perfluoropropylether
(Ellis et al., 2001).
Polymer
Thermal product identified (acronyms/formula and full name)
% produced
PTFE
TFE
Tertrafluoroethene
-
HFP
Hexafluoropropene
10.8
TFA
Trifluoroacetic acid
7.8
c-OFB
Octafluoro cyclobutane
-
CF3(CF2)nCOOH
Perfluorinated carboxylic acid
>0.01
F3CO(CF2)mCOOH
Trifluorometoxy perfluorinated carboxylic acid
-
DFA
Difluoroacetic acid
>0.01
MFA
Monofluoroacetic acid
>0.01
CPTFE/
CTFE
Chloro-trifluoroethene
-
PCTFE
CPFP
Chloro-pentafluoropropene
13.1
CDFA
Chlorodifluoroacetic acid
9.5
TFA
Trifluoroacetic acid
>0.1
DCHB
1,2-dichlorohexafluorocyclobutane
-
TCTFE
1,1,2-trichloro-1,2,2-trifluoroethane
-
1,3-DCTFP
1,3-dichlorotetrafluoropropene
-
1,1,3-TCTFP
1,1,3-trichlorotrifluoropropene
-
CF3(CF2)nCOOH
Perfluorinated carboxylic acid
-
ECTFE
TFA
Trifluoroacetic acid
6.3
CDFA
Chloro-difluoroacetic acid
7.2
HFP
Hexafluoropropene
-
CPFP
Chloro-pentafluoropropene
-
PFEPE
TFA
Trifluoroacetic acid
2.5
HFP
Hexafluoropropene
-
Thermolysis of Teflon, Kel-F, and other fluoro- and chlorofluoropolymers can
produce TFA and chlorodifluoroacetate (CDFA), either directly or indirectly via
products that are known to degrade to these haloacetates in the atmosphere. Figure
8 shows proposed reaction mechanisms involved in the thermolysis of a
fluoropolymer. The onset of thermal degradation of fluoropolymers is known to
initiate cleavage of the backbone and subsequent rearrangement to produce
significant amounts of TFA and CDFA. Thermolysis also leads to longer chain
polyfluoro and/or polyfluorochloro (C3-C14) carboxylic acid, compounds known
to be persistent. Finally, Ozone depleting substances like CFCs and greenhouse
gases like fluorocarbons, are among other thermal degradation products. This
suggests that thermolysis of fluoro- and fluorochloro-polymers may contribute to
ozone depletion and global warming (Ellis et al., 2001).
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Figure 8: Proposed reaction mechanisms involved in the thermolysis of a
fluoropolymer. The explicit major pathways for the production of TFA
are shown. As indicated by the bold arrow, the most significant step in
the thermal decomposition is the formation of carbine radicals. These
radicals then react with constituents present in the air, oxygen and
trace amounts of water, to form perfluorinated acids (n=0-12, m=1-7),
the yield being inversely proportional to the number of carbon atoms in
the chain. The distribution of product yield depends on temperature and
the composition of the atmosphere. A Δ indicates heat. (Ellis et al.,
2001).
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31
7 Greenhouse potential of fluoropolymer combustion
products
7.1 Thermal degradation products of fluoropolymers
One aim of the present study was to discuss whether greenhouse gases are formed
during fluoropolymer combustion. Some or all of the greenhouse gases discussed
in Chapter 6 may also have other sources. These sources may be natural, primarily
volcanic emissions (Francis et al., 1998; Gribble, 1995), or anthropogenic, such as
HFC and HCFC cooling gases (Jordan, 1999), anesthetic gases, use in aluminum
industry or metal coating as well as agrochemicals (Key et al., 1997; Ellis et al.,
2000), and their degradation products.
A number of atmospheric constituents influence the earth‟s climate through
radiative forcing (RF); these are called greenhouse gases. Radiative forcing is a
measure of the change of balance of incoming and outgoing energy in the Earth-
atmosphere system. This radiative balance controls the Earth‟s surface
temperature and the thermal variability throughout most of the atmosphere. The
term „forcing‟ indicates that the Earth‟s radiative balance is pushed away from its
normal/initial state (Forster et al., 2007). Hence, a positive RF implies global
warming, whereas a negative RF causes global cooling.
To be able to compare the impact of various factors on climate, the
Intergovernmental Panel on Climate Change (IPCC) in 1990 introduced the term
Global Warming Potential (GWP).The GWP of a compound i is the time-
integrated global mean RF of a pulse emission of 1 kg of this compound relative
to the RF of 1 kg of the reference gas CO2 (r). The UNFCCC have required use of
GWPs for many years for the calculation of countries‟ greenhouse gas emissions
(National Inventory Reports), and the GWPs listed in the Third Assessment
Report (TAR) of the IPCC were adopted for use in the Kyoto Protocol (Forster et
al., 2007). The GWP of component i is defined by (Forster et al., 2007; Blowers et
al., 2008):
where TH is the time horizon and t denotes time. The radiative efficiencies
(radiative forcing per unit amount/mixing ratio) for well-mixed greenhouse gases
are given in Table 12.
The greenhouse gases formed upon incineration of fluoropolymers are covered
either by the Montreal or the Kyoto protocols, as indicated in Table 10.
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32
Table 12: Names, chemical formula, abundances, lifetimes, radiative forcings
(given as W m–2) and GWP relative to CO2. The GWP were calculated
in the Third Assessment Report in a 100 year perspective. (IPPC
report: Forster et al., 2007; IPCC, 2001).
Gas
Chemical
formula
Abundance (ppt)
Lifetime
(years)
Radiative
forcinga
GWP#
100
years
2005
1998
1750
Other important greenhouse
gases
Carbon
dioxide [K]
CO2
3.79·106
3.66·106
2.75·106
50?
1.68
1
Methane [K]
CH4
1774
1745
700
12
0.48
23
Sulfur
hexafluoride
[K]
SF6
5.6
4.2
0
3200
0.0029
22200
CFC-11 [K]
CFCl3
251
268
0
45
0.063
4600
CFC-12 [K]
CF2Cl2
538
533
0
100
0.17
10600
Gases relevant for fluoropolymer
incineration
CFC-13 [M]
CClF3
NA
4
0
640
0.009§
14000
CFC-113 [M]
CCl2FCClF2
79
84
0
85
0.024
6000
HFC-23 [K]
CHF3
18
14
0
260
0.0033
12000
PFC-14 [K]
CF4
74
80
40
50000
0.0034
5700
PFC-116 [K]
C2F6
2.9
3.0
0
10000
0.0008
11900
PFC-318 [K]
c-C4F8
NA
NA
NA
3200
NA
10000
Total long lived greenhouse
gases
2.63
Total CFC
0.27
Total HCFC
0.04
Total
Montreal
gases
0.32
Other Kyoto gases (HFCs + PFCs +
SF4)
0.017
Halocarbons
0.34
a W m–2, values taken from Third assessment report
[M] Gas covered by the Montreal protocol
[K] Gas covered by the Kyoto protocol
§ Sum for CFC-13, CFC-114, and CFC-115 and the halons.
* Percent change in RF for the period 1998-2005
# GWP taken from TAR (IPCC, 2001)
When discussing the GWPs of the fluoropolymer degradation products, it is
convenient to divide them into three categories: stable neutral (saturated), unstable
neutral (unsaturated), and ionic and polar compounds:
i) Short-chained saturated, neutral, and stable perfluoro (PFCs),
chlorofluoro (CFCs), and hydrofluoro (HFCs) compounds have
long half-lives, a property important for exhibiting a significant
GWP. These compounds are postulated to affect global climate by
acting as greenhouse gases with GWPs between 5700 and 14000
(Table 10).
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33
ii) Unstable unsaturated neutral compounds formed during combustion of
fluoropolymers are short lived in the atmosphere. They do not
contribute to global warming and are not covered by the TAR.
iii) Polar and ionic compounds such as long-lived halocarboxylic
acids, e.g. TFA. They are expected to be removed from the
atmosphere through wet and dry deposition. The GWP of this
group is negligible due to the short atmospheric lifetime.
Short-chain saturated, neutral, and stable degradation products; PFC, CFC, and
HFC
The fluoropolymer combustion products CO2, CF4 (PFC-14), C2F6 (PFC-116), c-
OFB (PFC-318), CHF3 (HFC-23), CClF3 (CFC-13), and TCTFE (CFC-113) are
greenhouse gases covered by the TAR. DCHB (1,2-di-
chlorohexafluorocyclobuthane) is not covered by the TAR, but being a saturated
CFC, it should be considered as a greenhouse gas with a GWP comparable to the
other CFC gases discussed in the TAR. Fluorocarbons efficiently absorb infrared
radiation, particularly in the 1000-1400 cm–1 spectral range, where the atmosphere
originally is relatively transparent (Tuazon et al., 1993; McCulloch, 2003). Table
12 shows the GWP of the greenhouse gases listed in the TAR (IPCC, 2001). CF4
(PFC-14), C2F6 (PFC-116), c-OFB (PFC-318), CHF3 (HFC-23), CClF3 (CFC-13),
and TCTFE (CFC-113) all have very long atmospheric lifetimes and GWPs
considerably larger than that of CO2 (even though the large uncertainty regarded
the lifetime of CO2). The PFCs, CFCs, and HFCs possibly formed during
fluoropolymer waste incineration (see chapter 6) might therefore have a
considerable potential to influence the greenhouse effect when emitted in large
amounts.
The RF due to these compounds depends on the quantities and absorptivities of
the released atmospheric gases, and in this respect carbon dioxide dominates
because of the large quantities emitted. The total global RF values presented in the
2007 IPCC report were +0.017 0.002 W m–2 for the group consisting of HFC,
PFC and SF6, +0.32 0.03 W m–2 for the group consisting of CFC, HCFC and
chlorocarbons, and +1.66 0.17 W m–2 for CO2. Thus, the accumulation of
fluorocarbons in the atmosphere will enhance the warming of the atmosphere, but
compared to CO2 their contribution is small.
Unstable unsaturated degradation products
Neutral unsaturated degradation products with a short atmospheric lifetime, i.e.,
TFE, HFP, CTFE, CPFP, 1,3-DCTFP, 1,1,3-TCTFP, and PFIB will not have a
considerable affect on the global warming. TFE and HFP have atmospheric half-
lives of 1.9 and 6 days, respectively. No atmospheric half-lives are reported for
the combustion products CTFE, CPFP, 1,3-DCTFP, 1,1,3-TCTFP, and PFIB. The
unsaturated compounds have the potential to react with OH radicals (OH•) in the
troposphere to eventually produce TFA or other PFCA (100% conversion) in a
manner similar to that of HFP and TFE in Figure 9 above (Ellis et al., 2001).
Polar and ionic degradation products
PFCA and TFA are minor products emitted to the atmosphere from thermolysis of
fluoropolymers (Hurley et al., 2004). The global warming potential of TFA is
unknown, but it should be lower than CO2 given its short atmospheric life-time.
NILU OR 12/2009
34
PFCA, including TFA, and HF are removed from the atmosphere through wet or
dry deposition (Jordan, 1999).
PFCA, including TFA, and HF are removed from the atmosphere through wet or
dry deposition. Model calculations predicted a global mean TFA concentration in
precipitation in Europe of about 14 ng/L in 1995 and 120 ng/L in 2010. Already in
1999, TFA was found at 10-200 ng/L in precipitation and 60-600 ng/L in surface
water . It is hypothesized that the thermolysis of PTFE and other polyfluorinated
polymers is a major contributor to the steadily increasing concentrations of TFA
in urban environment precipitation. The global warming potential of TFA is
unknown, but it should be lower than CO2 given its short atmospheric life-time
(Jordan and Frank, 1999).
In addition to the anthropogenic sources, considerable natural sources of TFA and
other fluoroorganics are known. Volcanic emissions are reported to contain
several fluoroorganic compounds, and a summary is provided by Gribble and
references therein (Gribble, 2002). One other possible source is seafloor
hydrothermal vents (Scott et al., 2005). In most cases, the identified compounds
have not been quantified, thus it is difficult to estimate (except for HF) the
volcanic contribution to the atmospheric content of fluoro- and fluorochloro-
organic compounds.
The anthropogenic emissions of the non-greenhouse gas HF are primarily due to
coal combustion, and from the ceramics and metal industries (Caddle, 1980).
Assuming that all of the 0.123∙1012 g annually manufactured fluoropolymers
(Herzke et al., 2007) are combusted to HF, this will only account for 3% of the
total anthropogenic HF emission. According to the “Guide to the Safe Handling of
Fluoropolymer Resins” incineration for waste disposal is only recommended if the
incinerator is fitted and permitted to scrub out HF and other acidic combustion
gases, which is the case for all Norwegian incineration plants by legislation.
7.2 Possible contribution of incineration of fluoropolymers to global
warming
Does incineration of household waste containing fluoropolymers contribute
significantly to the total national emissions of green house gases in Norway? Do
these incineration products increase the atmospheric content of CFC, PFC, and
HFC, and hence contribute to global warming?
In order to contribute to global warming the fluoropolymers must be incinerated
and the produced greenhouse gases must be released into the environment. The
annual Norwegian fluoropolymer consumption is estimated to a maximum of 441
tons on the basis of the European consumption of fluoropolymers. However, the
amount ending in Norwegian incinerators remain largely unknown, due to lack of
data on amounts and types of fluoropolymers applied on products (inventory
needed), the amounts of fluoropolymer containing products ending up at
Norwegian MWIs as well as amounts of exported waste containing
fluoropolymers, incinerated in other countries. In addition, it is unclear how much
PFC is emitted via municipal waste incinerators in Norway and it is unknown if
the cleaning procedures of the exhaust are sufficient for removing PFCs.
NILU OR 12/2009
35
There exist only two studies where the emissions from thermal degradation of
fluoropolymers have been quantified (Clarke, 1992; Garcia, 2007).
Figure 9: Impact of oxygen and temperature on the formation of PFCs after the
combustion of PTFE (from Garcia et al., 2007)
As shown in figure 9, at 850°C and 30-50% oxygen present, C2F6 and CF4 are
formed in considerable yields.
However, no reports or studies exist where fluoropolymers are incinerated
together with other waste, and it has not been reported that HFC, CFC and PFC
have been identified in municipal incineration plant emissions so far.
This literature study has revealed that it is not possible to provide reliable
estimates for the magnitude of emissions of fluorine-containing green house gases
produced from fluoropolymers in Norwegian municipal incinerators.
In summary, incineration of fluoropolymer containing products has a great
potential contributing to a certain degree to the emissions of greenhouse gases of
Norway, but due to the lack of sound data on the fate of fluoropolymers in
Norway as well as of the chemical reactions in the different types of MWI plants
in Norway, no exact amounts can be given at this stage. However, according to
Garcia et al. (2007), PFC can be formed during the combustion of fluoropolymers.
Due to the high GWP (5700 and 11900, respectively, for PFC-14 and 116) a
potential significant input to the national CO2 equivalent budget might be possible
and needs to be investigated.
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36
8 Conclusions and evaluation of the need for further studies
PTFE is worldwide the most produced and consumed fluoropolymer followed by
PVDF and FEP. Therefore, it is assumed that these are also the main
fluoropolymers which end up in the municipal waste incinerators. However, a
broad spectrum of other fluorine containing polymers and fluoroelastomers are
currently introduced into our society with increasing volumes and applications. In
future years, they will end up in the domestic and industrial waste as well.
The thermolytic stability and degradation properties of PTFE have been in the
focus of the scientific community and the consumers for a long time already with
not always agreeing conclusions due to differing experimental conditions as for
example temperature, availability of oxygen, the physical form of the investigated
article, and the residence time at elevated temperature. The main products of
PTFE incineration at temperatures between 750 and 1050°C, relevant for
Norwegian waste incineration plants, are CF4 (PFC-14), CHF3 (HFC-23), C2F6
(PFC-116), TFE and HFP. Only a few studies have been conducted where the
yields of these compounds in relation to thermolysis conditions have been
investigated. The most potent greenhouse gases formed by fluoropolymer
combustion are compounds containing C–F bonds, which absorb electromagnetic
radiation in the spectral range 1000-1400cm–1, namely CF4 (PFC-14), C2F6 (PFC-
116), TFE, and HFP. The latter two are rapidly degraded in the atmosphere and do
not contribute to global warming. The GWP of CF4 (PFC-14) and C2F6 (PFC-116)
are 5 700 and 11 900, respectively (TAR; IPCC, 2001).
Since all kinds of quantifications of possible emissions rely on only few studies
on that subject, realistic emission numbers cannot be achieved, and can only be
determined through direct measurement of exhaust from MWIs.
Additionally Norwegian waste is not only handled in Norway. Waste export to
other countries (mainly Europe) for incineration purposes occurs, with other
regulations for MWI plant emissions, adding to any global inputs. To make the
picture more complex Norway is importing waste as well from several countries
with no information on the content of fluoropolymers (Miljøstatus Norge).
No information was available regarding on-site measurements of decomposition
products of fluoropolymers in municipal incinerators. On-site investigations for
revealing a realistic impression on the compounds formed in Norwegian
municipal incinerators are necessary in order to assess the extent and the
composition of the organofluorine emissions.
8.1 Recommendation on future investigations
As documented above, the results and conclusions concerning the thermal
degradation products of fluoropolymers varies severely, depending on
experimental set-up. Applied temperatures, oxygen content, moisture, other gases
and metals reacting as catalysts might influence the outcome of the experiments
dramatically without reflecting the conditions in an incinerator correctly. Hence it
is not recommended to run laboratory incineration experiments on fluoropolymer
materials. Experimental incineration cannot be compared directly to waste
NILU OR 12/2009
37
incinerators due to the complex mixture of waste burned in a municipal waste
incinerator. Even between the incinerators differences in construction, especially
in air pollution control filter systems, lead to different emission values. Therefore,
on-site studies in Norwegian waste incinerators are recommended.
Sampling should be performed in different types of incinerators for comparing
emission values between different constructions. A known fluoropolymer content
of the waste incinerated during sampling would be of help in order to quantify
emitted amounts of greenhouse gases. Already installed sample equipment for air
monitoring can be used in some incinerators. Waste is often sorted and therefore
the incinerators are run in different modes. It is recommended to investigate the
decomposition products within these different incineration runs, in order to gain
more and distinguished information on waste composition and their related
degradation products.
The waste incinerators proposed for sampling are given in Table 13.
Table 13: Waste incinerators suggested to be included in future investigations.
Type of incinerator
The localization of the incinerator
Large MWI
Brobekk
Klemetsrud
Small MWI
Senja
Dangerous waste MWI
NORCEM Brevik
Standard air sampling in the chimney at standard sampling point
6 samples per location to cover different days and varying modes of incineration
Following analytes and groups of analytes are recommended:
Hydrogenfluoride (HF)
Chlorofluorocarbons (CFCs)
Hydrochlorofluorocarbons (HCFCs)
Hydrofluorocarbons (HFCs)
Perfluorinated compounds (PFCs)
Sampling methods and analysis for HF, CFCs, HCFCs, HFCs and some PFCs
(e.g. SF6, C2F6) are established and included in the proposed costs. Methods for
sampling and analysis of some PFCs; e.g., TFE and HFP, are not commercially
available and have to be developed.
Finally, a life cycle assessment of the imported fluoropolymers should be
conducted to obtain more reliable estimates for the amount of fluoropolymers that
is incinerated and hence the potential amount of greenhouse gases emitted due to
fluoropolymer incineration. The incineration of Norwegian waste in other
countries and the import and fate of international waste should be part of that
study as well. The determined amounts may be used in an extrapolatory manner to
estimate the total amount of the annually emitted amount of fluoro-containing
gases in Norway. Further the amount of CClF3 (CFC-13), CF4 (PFC-14), C2F6
(PFC-116), and c-OFB (PFC-318) originating from fluoropolymer incineration
must be related to the total national and global emissions of these compounds and
other greenhouse gases, a topic which is beyond the scope of the present work.
NILU OR 12/2009
38
9 References
Acerboni, G., Beukes, J.A., Jensen, N.R., Hjorth, J., Myhre, G., Nielsen, C.J. and
Sundet, J.K. (2001) Atmospheric degradation and global warming
potentials of three perfluoroalkenes. Atmos. Environ., 35, 4113-4123.
Ameduri, B., Boutevin, B. and Kostov, G. (2001) Fluoroelastomers: synthesis,
properties and applications. Prog. Polym. Sci., 26, 105-187.
Baker, Jr. B.B. and Kasprzak, D,J. (1993) Thermal degradation of commercial
fluoropolymers in air. Polym. Degrad. Stab., 42, 181-188.
Bhadury, P.S., Singh, S., Sharma, M. and Palit, M. (2007) Flash pyrolysis of
polytetrafluoroethylene (teflon) in a quartz assembly. J. Anal. Appl. Pyrol.,
78, 288-290.
Blowers, P., Moline, D.M., Tetrault, K.F., Wheeler, R., Ronald, X. and
Tuchawena, S.L. (2008) Global warming potentials of hydrofluoroethers.
Environ. Sci. Tech., 42, 1301-1307.
Boucher, M., Ehmler, T. J. and Bermudez, A.J. (2000) Polytetrafluoroethylene
gas intoxication in broiler chickens. Avian Dis., 44, 449-453.
Cadle, R.D. (1980) A comparison of volcanic with other fluxes of atmospheric
trace gas constituents. Rev. Geophys., 18, 746-752.
Chen, D.M., Hsieh, W.H., Snyder, T.S., Yang, V., Litzinger, T.A. and Kuo, K.K.
(1991) Combustion behavior and thermophysical properties of metal-based
solid fuels. J. Propul. Power, 7, 250-257.
Clarke, F.B., Vankuijk, H., Valentine, R., Makovec, G.T., Seidel, W.C., Baker,
B.B., Kasprzak, D.J., Bonesteel, J.K., Janssens, M. and Herpol, C. (1992)
The toxicity of smoke from fires involving perfluoropolymers: full-scale
fire studies. J. Fire Sci., 10, 488-527.
Daikin Industries (2008) URL: http://www.daikin.com/index.html.
Drobny, J.G. (2001) Technology of fluoropolymers. Boca Raton, CRC press LLC.
Ebnesajjad S. (2008) Introduction to fluoropolymers. URL:
http://fluoroconsultants.
com/sitebuildercontent/sitebuilderfiles/introductiontofluoropolymers.pdf.
Ellis, D.A. and Mabury, S.A. (2000) The aqueous photolysis of TFM and related
trifluoromethylphenols. An alternate source of trifluoroacetic acid in the
environment. Environ. Sci. Tech., 34, 632-637.
Ellis, D.A., Martin, J.W., Muir, D.C.G. and Mabury, S.A. (2003) The use of F-19
NMR and mass spectrometry for the elucidation of novel fluorinated acids
and atmospheric fluoroacid precursors evolved in the thermolysis of
fluoropolymers. Analyst, 128, 756-764.
Ellis, D.A., Mabury, S.A., Martin, J.W. and Muir, D.C.G. (2001) Thermolysis of
fluoropolymers as a potential source of halogenated organic acids in the
environment. Nature, 412, 321-324.
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39
European Environment Agency (2008) Air pollution by ozone across Europe
during summer 2007. Copenhagen, European Environment Agency
(Technical report No 5/2008).
Fluoropolymer Division (2007) Fpd material suppliers.
URL: http://www.fluoropolymers.org/index.htm.
Fluoropolymer Division (2008) URL: http://www.fluoropolymers.org/index.htm.
Forbes, N.A. (1997) PTFE toxicity in birds. Vet. Rec., 140, 512.
Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D.W.,
Haywood, J., Lean, J., Lowe, D.C., Myhre, G., Nganga, J., Prinn, R.,
Raga, G., Schulz, M. and, Van Dorland, R. (2007) Changes in
atmospheric constituents and in radiative forcing. In: Climate change
2007: The physical science basis. Contribution of Working Group I to the
fourth assessment report of the Intergovernmental Panel on Climate
Change. Ed. by: Solomon, S. et al. Cambridge, United Kingdom and New
York, NY, USA, Cambridge University Press. pp. 129-234.
Francis, P., Burton, M.R. and Oppenheimer, C. (1998) Remote measurements of
volcanic gas compositions by solar occultation spectroscopy. Nature, 396,
567-570.
Frank, H., Christoph, E.H., Holm-Hansen, O. and Bullister, J.L. (2002)
Trifluoroacetate in ocean waters. Environ. Sci. Tech., 36, 12-15.
Freedonia (2007) Fluoropolymers. US industry study with forecasts for 2001 &
2016. Cleveland, Freedonia Group.
Garcia, A.N., Viciano, N. and Font, R. (2007) Products obtained in the fuel-rich
combustion of PTFE at high temperature. J. Anal. Appl. Pyrol., 80, 85-91.
Gribble, G. (1995) Volcanic CFCs-response. Environ. Sci. Tech., 29, A8-A8.
Herzke, D. (1998) Polyfluorinated dibenzo-p-dioxines and benzofuranes:
Synthesis, properties, analyses, formation and toxicology. Berlin,
Technical University of Berlin.
Herzke, D., Schlabach, M., Mariussen, E., Uggerud, H. and Heimstad, E. (2007)
A literature survey on selected chemical compounds. Oslo, Norwegian
Pollution Control Authority (TA-2238/2007).
Hurley, M.D., Sulbaek Andersen, M.P., Wallington, T.J., Ellis, D.A., Martin, J.W.
and Mabury, S.A. (2004) Atmospheric chemistry of perfluorinated
carboxylic acids: reaction with OH radicals and atmospheric lifetimes. J.
Phys. Chem. A, 108, 615-620.
Inoguchi, Y. and Loechner, U. (2006) Fluoroelastomers. CEH marketing research
report. SRI Consulting.
IPPC (2001) Climate Change 2001: The scientific basis. Contribution of Working
Group I to the third assessment report of the Intergovernmental Panel on
Climate Change. Ed. by: Houghton, J.T. et al. Cambridge, United
Kingdom and New York, NY, USA, Cambridge University Press.
Johns, K.and Stead, G. (2000) Fluoroproducts - the extremophiles. J. Fluor.
Chem., 104, 5-18.
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40
Jordan, A. and Frank, H. (1999) Trifluoroacetate in the environment. Evidence
for sources other than HFC/HCFCs. Environ. Sci. Tech., 33, 522-527.
Key, B.D., Howell, R.D. and Criddle, C.S. (1997) Fluorinated organics in the
biosphere. Environ. Sci. Tech., 31, 2445-2454.
Kitahara, Y., Takahashi, S., Kuramoto, N., Šala, M., Tsugoshi, T., Sablier, M. and
Fujii, T. (2009) Ion attachment mass spectrometry combined with infrared
image furnace for thermal analysis: Evolved gas analysis studies. Anal.
Chem., 81, 3155-3158.
Ko, M.K.W., Sze, N.D., Rodríguez, J.M., Weistenstein, D.K., Heisey, C.W.,
Wayne, R.P., Biggs, P., Canosa-Mas, C.E., Sidebottom, H.W. and Treacy,
J. (1994) CF3 chemistry: potential implications for stratospheric ozone.
Geophys. Res. Lett., 21, 101-104.
Koch, E.C. (2002) Metal-fluorocarbon-pyrolants IV: Thermochemical and
combustion behaviour of magnesium/teflon/viton (MTV). Propellants,
Explos., Pyrotec., 27, 340-351.
Mashino, M., Ninomiya, Y., Kawasaki, M., Wallington, T.J. and Hurley, M.D.
(2000) Atmospheric chemistry of CF3CF=CF2: kinetics and mechanism
of its reactions with OH radicals, Cl atoms, and ozone. J. Phys. Chem. A,
104, 7255-7260.
McCulloch, A. (2003) Fluorocarbons in the global environment: a review of the
important interactions with atmospheric chemistry and physics. J. Fluor.
Chem., 123, 21-29.
OECD (2007) Report of an OECD workshop on perfluorocarboxylic acids
(PFCAs) and precursors. Paris, OECD (ENV/JM/MONO(2007)11).
Papadimitriou, V.C., Talukdar, R.K., Portmann, R.W., Ravishankara, A.R. and
Burkholder, J.B. (2008) CF3CF[double bond, length as m-dash]CH2 and
(Z)-CF3CF[double bond, length as m-dash]CHF: temperature dependent
OH rate coefficients and global warming potentials. Phys. Chem. Chem.
Phys., 10, 808-820.
Parker, M.P. (2006) The world market of fluoropolymers in primary forms: a
2007 global trade perspective. San Diego, Icon group international.
Posner, S., Herzke, D., Poulsen, P.B. and Jensen, A.A. (2007) PFOA in Norway –
Survey of national sources, 2007. Oslo, Norwegian Pollution Control
Authority (TA-2354/2007).
Powley, C.R., Michalczyk, M.J., Kaiser, M.A. and Buxton, L.W. (2005)
Determination of perfluorooctanoic acid (PFOA) extractable from the
surface of commercial cookware under simulated cooking conditions by
LC/MS/MS. Analyst, 130, 1299-1302.
Richardson, M. (1991) Teflon toxicity from heat lamps. J. Assoc. Avian Vet., 5,
192.
Ring, K.L., Kalin, T. and Kishi, A. (2002) Fluoropolymers. CEH marketing
research report. SRI Consulting.
Scheirs, J. (2001) Fluoropolymers: technology, markets and trends. Rapra
industry analysis report. Rapra Technology.
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Scheirs, J. (1997) Modern fluoropolymers. Chichester, John Wiley & Sons.
Scott, B.F., Macdonald, R.W., Kannan, K., Fisk, A., Witter, A., Yamashita, N.,
Durham, L., Spencer, C. and Muir, D.C.G. (2005) Trifluoroacetate profiles
in the Arctic, Atlantic, and Pacific oceans. Environ. Sci. Tech., 39, 6555-
6560.
SPIN (2008) SPIN Substances in Products in the Nordic Countries. URL:
www.spin2000.net
Tobiesen, A. (2006) Assessment of information assessible on Teflon and
degradation products of Teflon (Cas 9002-84-0). Oslo, SFT-NIVA (In
Norwegian).
URL: http://www.sft.no/nyheter/dokumenter/teflon_miljorisiko_niva.pdf
The Society of the Plastics Industry (2005) The guide to the safe handling of
fluoropolymer resins – fourth edition. Bp-101. Washington, SPI.
Tuazon, E.C. and Atkinson, R. (1993) Tropospheric transformation products of a
series of hydrofluorocarbons and hydrochlorofluorocarbons. J. Atmos.
Chem., 17, 179-199.
Waritz, R.S. (1975) An industrial approach to evaluation of pyrolysis and
combustion hazards. Environ. Health Perspect., 11, 197-202.
Will, R., Kaelin, T. and Kishi, A. (2005) Fluoropolymers. CEH marketing
research report. SRI Consulting.
Yamada, T., Taylor, P.H., Buck, R.C., Kaiser, M.A. and Giraud, R.H. (2005)
Thermal degradation of fluorotelomer treated articles and related
materials. Chemosphere, 61, 974-984.
Zuev, V. V., Bertini, F. and Audisio, G. (2006) Investigation on the thermal
degradation of acrylic polymers with fluorinated side-chains. Polymer
Degrad. Stabil., 91, 512-516.
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Appendix 1 : Review of the SFT report on PTFE
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Review of the report ”Miljøvurdering av miljøinformasjon vedrørende Teflon og
nedbrytningsprodukter fra Teflon (Cas 9002-84-0)”. Remarks are given in respect
to the chapters of the report.
Background
Up-to-date produced amounts for Teflon and other fluoro- and
chlorofluoropolymers are included in chapter 4.4 Production and consumption
of fluoropolymers.
Emissions caused by the use of Teflon products
Additionally to Washburn‟s experiments another research group, which
included also DuPont researchers, came to the same results that no PFOA is
extractable during the cooking procedure with commercial cookware (Powley
et al., 2005). How hot can cookware become by inobservant use? An in-vivo
cooking study to check the extractable fluorinated amount by cooking different
kind of meals with different lipid and water content could be interesting. But
since only literature from major PTFE producers is available undependent
studies are needed to assess the total potential of PTFE to form hazardous
degradation products.
Depending on the fluoropolymer and finished product manufacturing
conditions, it is theoretically possible that small quantities of residual gases,
including perfluoroisobutylene (PFIB), hexafluoropropylene HFP),
tetrafluoroethylene (TFE) and hydrogenfluoride (HF) may be trapped and
slowly evolve from resins as well as finished products. Testing some finished
products has confirmed that PFIB and HDP can be found in the finished
products, but the conditions under what these compounds form and in what
quantities, has not been investigated. These gases can accumulate in
unventilated spaces (e.g. closed storage rooms, closed trucks, etc.) at levels
that may be hazardous if the quantities of fluoropolymer materials and
products stored are large (The Society of the Plastic Industry, 2005).
Heat lamp bulbs which are often used for animal breeding were found to be
PTFE coated. The surface temperatures are around 200°C (Boucher et al.,
2000). PTFE toxicosis from heat lamps has been reported in captive raptors
(Forbes, 1997), birds at the San Antonio Zoo (Richardson, 1991), broiler
chickens and on a duck research farm (Boucher et al., 2000).
Emissions caused by waste handling
The type of decomposition product depends on the conditions under which
heatingoccurs.
Temperature, availability of oxygen, the physical form of the article, and the
residence time at elevated temperatures; are among the factors that determine
the ultimate nature of the decomposition products. The four main types of
products formed in the decomposition of fluoropolymers are fluoroalkenes,
hydrogen fluoride (HF), oxidation products, and low-molecular-weight
fluoropolymer particulates. The presence of other monomers or additives in
the fluoropolymer resin may change the nature of the decomposition products
(The Society of the Plastic Industry, 2005).
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As the PTFE temperature increases to approximately 450°C in air, carbonyl
fluoride (COF2) and hydrogen fluoride (HF) become the main decomposition
products. Carbonyl fluoride hydrolyzes rapidly in the presence of moist air to
hydrogen fluoride and carbon dioxide (CO2). Small amounts of
hexafluoropropylene (HFP) may also be found at these temperatures. The
highly toxic chemical, perfluoroisobutylene (PFIB), has been detected as a
minor product at temperatures above 475°C. When temperatures reach
approximately 800°C, tetrafluoromethane begins to form (The Society of the
Plastic Industry, 2005).
Koch, 2002, could show that at 460°C an exothermal decomposition reaction
accompanied by weight loss starts and is completed at approximately 610°C
where all of the starting material has been consumed (100% weight loss). The
constituents of the thermal decomposition reaction in air are mainly COF2,
tetrafluoroethylene (C2F4) and difluorocarbene (CF2). In presence of humidity
also hydrogen-containing products such as fluoroform (CHF3) and HF are
formed. In addition thermal decomposition has been studied in vacuum. Under
this condition the decomposition is an endothermic process yielding a mixture
of the monomer and acyclic as well as cyclic fluorocarbons. Under argon gas
the decomposition starts at 512°C and in nitrogen at 486°C. Similarly
decomposition under inert atmosphere is an endothermic process yielding a
similar product distribution as under vacuum. The distribution of PTFE
decomposition products at temperatures between 727 and 472°C are CF2 as
mjor product, CF4, solid carbon (C8) and atomic fluorine. It has been found that
release of gaseous products upon thermal treatment of PTFE may be
suppressed by addition of nonvolatile basic compounds such as calcium
hydroxide (Ca(OH)2) and sodium hydroxide (NaOH) (Boucher et al.,
2000,Koch, 2002).
In the “Guide to the Safe Handling of Fluoropolymer Resins” (The Society of
the Plastic Industry, 2005) a regulatory information for waste disposal is
advised. Preferred options are recycling and landfill. Incinerate only if the
incinerator is fitted and permitted to scrub out HF and other acidic combustion
gases.
TFA
The environmental fate of TFA is adequately described. There are no new
reports describing novel degradation pathways of TFA. TFA therefore still
must be regarded as persistent.
Volcanic emissions are reported to contain several fluoroorganic compounds,
and a summary is provided by Gribble (Gribble 2002) and references therein.
TFA is found at higher concentrations than what can be accounted for.
Therefore TFA is believed to have a major non-anthropogenic source, but this
has yet to be identified (Gribble 2002), although this is disputed (Ellis et al.,
2001). One possible source is seafloor hydrothermal vents (Scott et al., 2005).
In most cases, the identified compounds have not been quantified, thus it is
difficult to estimate (except for HF) the volcanic contribution to the
atmospheric content of fluoro- and fluorochloro-organic compound. However,
considered the very large volumes of volcanic emissions, they cannot be
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neglected and might exceed emissions caused by fluoropolymer-thermolysis
considerably.
The environmental effects of TFA towards plants and aquatic organisms are
thoroughly described.
Fate of degradation products of Teflon after pyrolysis ’
The research group of Garcia et al (2007) carried out thermal degradation of PTFE
in a horizontal tubular reactor. The influence of the temperature and the reaction
atmosphere on the degradation products generated has been studied. Different
runs (pyrolysis and fuel rich atmosphere) in the range 750–1050 °C were
performed. In pyrolysis runs, only C2F4 and C3F6 as perfluorocarbon compounds
were found. Under oxidative conditions, C2F6, C3F6 and CF4 were detected,
varying their percentages as a function of temperature and oxygen proportion in
the atmosphere. A low percentage of semivolatiles were also analyzed in all the
cases studied, although only few fluorinated compounds were identified in this
group.
The atmospheric lifetimes of gaseous 1-4-carbon PFCAs and PFOA have
been examined and are thought to be dependent on removal by wet and dry
deposition rather than removal by reaction with hydroxyl radicals.
Atmospheric lifetimes for gaseous PFOA of a few days to several weeks have
been estimated.
PFCAs resist degradation via oxidation, hydrolysis or reduction.
Conclusions
The conclusion claiming that normal use of teflon lined cooking vessels do not
emit hazardous compounds is supported.
No additional data on waste incineration treatment plants and the forming of
PTFE degradation gasses in these plants is available in the literature.
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Appendix 2; List of Fluoropolymers
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Appendix II-I: List of fluoromono and -polymer compounds mainly used in the world marked.
Type
Chemical name
CAS No.
Chemical formula
Fluoromonomers:
TrFE
trifluoroethylene
359-11-5
C2HF3
TFE
tetrafluoroethylene
116-14-3
CF2=CF2
TFP
3,3,3-trifluoropropylene
677-21-4
C3H3F6
HFP
hexafluoropropylene
9003-53-6
C3F6
HFPO
Hexafluoropropylene Oxide
428-59-1
C3F6-O
PFBE
perfluorobutylethylene
19930-93-4
C6H3F9
PVF
polyvinyl fluoride
24981-14-4
C2H3F
VDF, VF2
vinylidene fluoride
75-38-7
C2H2F2
PVDF
polyvinylidene fluoride
24937-79-9
(C2H2F2)n
PMVE
perfluoromethyl vinyl ether
1187-93-5
C14H24O2
PEVE
perfluoroethyl vinyl ether
10493-43-3
C4H3F5O
PPVE
perfluoropropyl vinyl ether
1623-05-8
C5F10O
PSEPVE
Perfluoro-2-(2-
fluorosulfonylethoxy) Propyl
Vinyl Ether
16090-14-5
FSO2CF2CF2OCF(CF3
)CF2OCF=CF2
EVE
Esther vinyl ether
63863-43-4
CTFE
chlorotrifluoroethylene
79-38-9
C2ClF3
DFDCE
1,2-difluoro-1,2-
dichloroethylene
598-88-9
C2Cl2F2
PCDFE
1,1-dichloro-2,2-
difluoroethylene
79-35-6
C2Cl2F2
HFIB
hexafluoroisobutylene
382-10-5
C4H2F6
HFIBO
Hexafluoroisobutylene
epoxide
31898-68-7
cyclo–
C(CF3)2CH2O–
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Type
Chemical name
CAS No.
Chemical formula
Fluoropolymers:
ETFE
Ethylene-tetrafluoroethylene
copolymer
68258-85-5
(CF2-CF2)m-(CH2-
CH2)n
ECTFE
ethylene-
chlorotrifluoroethylene
copolymer
25101-45-5
[(CH2- CH2)x-(CFCl-
CF2)y]n
PCTFE
Polychlorotrifluoroethylene
9002-83-9
(CF2- CFCl)n
FEP
tetrafluoroethylene-
hexafluoropropylene
copolymer
25067-11-2
[(CF(CF3)-CF2)x(CF2-
CF2)y]n
PFA
Perfluoroalkoxyethylene
(perfluoroalkoxyalkane)
26655-00-5
PTFE
polytetrafluoroethylene
9002-84-0
(CF2-CF2)n
EFEP
Copolymer of ethylene, TFE
and HFP
25038-71-5
[(CH2- CH2)x-(CF2-
CF2)y(CF(CF3)-
CF2)z]n
TFE-P
Copolymer of TFE and
propylene
-
HTE
Copolymer of HFP, TFE and
ethylene
-
MTFA
methyltrifluoroacrylate
392-41-6
TFMAA
α-(Trifluoromethyl) acrylic
acid
MFA
Copolymer of TFE and
PMVE
957766-98-2
THV
Terpolymer of TFE, HFP,
VDF
25190-89-0
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Appendix II-II: This table lists the key fluoropolymers, reprocessed PTFE and melts, filled
compounds, concentrates, coatings, and fluoroelastomers, plus the material suppliers
and their trademarks (Fluoropolymer Division, 2007).
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Appendix 3: List of intermediates produced by
Daikin (Daikin Industries, 2008).
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Norwegian Institute for Air Research
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Environmental Research Alliance of Norway
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REPORT SERIES
OR
REPORT NO. OR 12/2009
ISBN: 978-82-425-2085-2 (printed)
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ISSN: 0807-7185
DATE
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SIGN.
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PRICE
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TITLE
Emissions from incineration of fluoropolymer materials
PROJECT LEADER
Dorte Herzke
A literature survey
NILU PROJECT NO.
O-108099O-108099
AUTHOR(S)
Sandra Huber, Morten K. Moe, Norbert Schmidbauer, Georg H.Hansen,
Dorte Herzke
CLASSIFICATION *
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CONTRACT REF.
2008/401 and 2009/1407
REPORT PREPARED FOR
SFT, Ingunn Myhre, Pål Spillum
ABSTRACT
The Norwegian Pollution Control Authority (SFT) commissioned a literature survey on incineration of
fluoropolymer materials, overviewing the available literature on formation of greenhouse gases until August 2008.
The survey provides the foundation on which decisions for the future needs for further investigations will be made.
Suggestions for sampling were also part of the study.
NORWEGIAN TITLE
Utslipp ved forbrenning av fluoropolymer materiale
KEYWORDS
fluoropolymerer, klimagasser,
forbrenning,
PTFE
ABSTRACT (in Norwegian)
[Skriv abstract på norsk]
* Classification
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B
C
Unclassified (can be ordered from NILU)
Restricted distribution
Classified (not to be distributed)
REFERENCE:
O-108099O-108099
DATE:
14.12.2009
ISBN: 978-82-425-2085-2 (printed)
978-82-425-2086-9 (electronic)
NILU is an independent, nonprofit institution established in 1969.
Through its research NILU increases the understanding of climate
change, of the composition of the atmosphere, of air quality and of
hazardous substances. Based on its research, NILU markets
integrated services and products within analyzing, monitoring and
consulting. NILU is concerned with increasing public awareness
about climate change and environmental pollution.
REFERENCE:
O-108099
DATE:
14.12.2009
ISBN: 978-82-425-2085-2 (printed)
978-82-425-2086-9 (electronic)
NILU is an independent, nonprofit institution established in 1969.
Through its research NILU increases the understanding of climate
change, of the composition of the atmosphere, of air quality and of
hazardous substances. Based on its research, NILU markets
integrated services and products within analyzing, monitoring and
consulting. NILU is concerned with increasing public awareness
about climate change and environmental pollution.
