Licentitate kappa steffen 27-10-161040506/FULLTEXT01.pdf · of impurities and their gradual...

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Abstract

Environmental pollution caused by persistent perfluoroalkyl acids (PFAAs) – organic

chemicals with confirmed levels of toxicity and propensity for bioaccumulation – has given

rise to global environmental concerns. Functional textiles containing durable water repel-

lents (DWRs) that are based on side-chain fluorinated polymers are noted to be major

contributors to the release of such environmental pollutants. This results from the release

of impurities and their gradual degradation. Nevertheless, the properties of DWRs based

on long chain perfluoroalkyl chains result in exceptional material performance in repellent

textiles and are therefore hard to replace without detriment to textile quality. This thesis

aims to characterise the currently available DWR alternatives by assessing their technical

performance and potentiality as hazardous chemicals with respect to estimated emission

scenarios. Furthermore, the work carried out herein suggests that by taking a segmented

perspective of the textile market, substitution of fluorinated materials with more environ-

mentally benign alternatives where peak material performance is not required might offer

a better solution. In addition, the thesis proposes directions for future research that may

be considered essential for a more thorough and robust understanding of the environ-

mental fate of DWR-polymers and how best to reduce defuse emissions of PFAAs.

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Table of Contents

List of studies..........................................................................................................................................iii

1. Introduction......................................................................................................................................1

1.1 The SUPFES project-how Academia and Industry work together......................................3

1.2 Textile repellency.......................................................................................................................4

1.3 Aims and objectives of the thesis............................................................................................6

2. Summary of papers.........................................................................................................................7

2.1 Paper I: Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing........................................................................7

2.2 Paper II: Performance evaluation of state-of-the-art durable water repellents for PA and PES fabrics...................................................................................................................................11

3. Discussion......................................................................................................................................13

4. Future work.....................................................................................................................................16

References..............................................................................................................................................18

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List of studies

Paper I

H. Holmquist; S. Schellenberger, S.; I. van der Veen; G.M. Peters; P.E.G. Leonards; I.T. Cousins (2016). Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing. Envi-ronment International. 91:251-264

My contributions:

(1) Co-authored article (shared first authorship) with Hanna Holmquist (Stockholm Uni-

versity). Developed the idea of the study together with the co-authors.

(2) Performed the research and wrote the corresponding text for the structure-property

relationships of durable water repellents (DWRs)

(3) Produced Figure 1

(4) Produced Figures 2 and 3 together with Hanna Holmquist

Paper II

S.Schellenberger; P. Gillgard; A. Stare; A-C. Hanning; O. Levenstam; K. Otterquist; F. Toomadj; I.T. Cousins (2016). Performance evaluation of state-of-the-art du-rable water repellents for PA and PES fabrics. Textiles Research Journal, In preparation for submission.

My contributions:

(1) I wrote the article, with contributions from co-authors, and developed the idea of the

study together with Philip Gillard.

(2) Performed the sampling application and initial repellency test of alternative DWRs

and interpreted the data.

(2) Measured contact angles with the help of special fabric holder construction together

with Oscar Levenstam.

(3) Interpreted the data from the durability test of alternative DWRs that were conducted

by Anne Star under the supervision of Anne-Charlotte Hanning.

(4) Produced Figures 1-7.

LICENTIATE THESIS: Properties of Alternative Durable Water Repellent Chemicals for Textiles

Acknowledgements I would like to thank my supervisors Ian Cousins and Philip Gillard for their support and

patience in writing this thesis. Also I thank my colleagues in the SUPFES project. In par-

ticular, I would like to mention Hanna Holmquist for the enlightening discussions during

the work on the first paper in this thesis.

I would also like to thank all my colleagues in Swerea IVF for introducing me to the field

of functional textile research. I would like to especially mention Anne Star and Oskar Le-

venstam who helped me with the practical experiments for the second paper as well as

Sandra Roos who organized the financial support for Oskar Levenstam’s work. Further-

more, I would like thank Farashad Toomadj, Kaj Otterquist and Anne-Charlotte Hanning

who helped me conduct the practical setup of the experiments. Finally, I would like to

thank my office mate, Anton Ribbenstedt, and another ACES colleague, Samuel Lowe,

for inspiration and for proofreading this thesis. All other ACES colleagues are thanked

for contributing to the great work environment in our department.

Stockholm, October


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1. Introduction

Ever since humans lost their hair during evolution1 functional textiles have been the most

popular materials for protection against bad weather conditions. Besides insulation,2 a

fabric’s repellency3 is its most fundamental function to ensure the thermal stability of the

human body. The invention of rubberized fabrics4 by Charles MacIntosh in 1823 led to

textiles with good water resistance, but poor regulation of human body moisture. They

were therefore unsuitable for active outdoor pursuits that increased the body’s liquid loss5.

Since then, various improvements have been made6,7,8 in order to produce durable water

repellents (DWRs) that enable fabrics to withstand penetration by water9 and which also

promote the release of body moisture. One of the more successful approaches has been

to employ polymers that contain wax- or fatty acid-based hydrophobic groups which form

a continuous film around the single fibers of the textiles. This concept combines two mu-

tually contradictory functions, the moisture permeability10 that is realized by the porosity

of the woven fabric and water repellency that is achieved by hydrophobic groups.

The first fluorinated DWRs following this approach were discovered by a technician of the

company, 3M, who accidently spilled some drops of fluorochemical liquid on her shoes11.

When applying different liquids for cleaning purposes, the surface of the shoes appeared

to have great liquid repellency towards water, alcohol or other solvents. This observation

caused the development of DWRs using side-chain fluorinated polymers (SFPs) in the

late 1950s with side chains synthesized through electrofluorination12,11 or telomerisa-

tion.13

Figure 1: Schematic representation of the structural principle14 of side-chain fluorinated polymer (SFP) for textile applications with (a1) an anchor group that provides the chemical fixation to the textiles and cross-linking of the DWR-coating (a2) the polymer that provides durability and connection to other copolymers (a3) a flexible spacer (e.g. ¾C2H4 ¾) which facilitates the orientation of (b1) the hydro- and oleophobic perfluoroalkyl chain with (b2) at typical chain length distribution of technical fluorotelomer-based DWR pro-duced before 2009.15 Due to their surprisingly properties in creating omniphobic16 fabrics (repellency towards

polar and non-polar liquids), SFPs are up until the present day the predominant polymers

used in functional textiles with high product requirements17. Especially in combination with

waterproof membranes (based on stretched polytetrafluorethylene (PTFE)18), fabrics with


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a multilayered construction revolutionized the outdoor and performance sportswear with

materials that were originally developed for space missions or medical applications17.

Figure 1 depicts a typical structural building principle and chain length distribution of SFPs

based on long perfluroralkyl chains (described as l-SFPs in this work). Despite their great

material properties l-SFPs have been found to release persistent, bioaccumulative and

toxic perfluoroalkyl acids19,20 (PFAAs) such as perfluorooctanoic acid (PFOA) and other

perfluoroalkyl carboxylic acid (PFCA) homologues into the environment (see Figure 5).

The discharge of these persistent environmental pollutants can be a result of impurities

that enter products during production21 or gradual degradation of SFPs during the life

cycle of textiles22. Consequently, fluorinated DWRs are the subject of worldwide debate23

and l-SFPs are therefore part of an ongoing phase-out24;25. Due to the pressure on fluo-

rochemical manufacturers by regulatory authorities26, eight major flourochemical produc-

ers (collectively represented by the FluoroCouncil) joined in a global stewardship pro-

gram.24”. In 2006, members of the FluoroCouncil “voluntarily” committed to eliminate the

global use of PFOA and related chemicals through the 2010/2015 PFOA Stewardship

Program. The aim was to eliminate manufacture, use and product content by 2015. Ad-

ditional campaigns, like Greenpeace`s DETOX28 focused on emissions from products

made by well-known textile brand names29,30 with the goal of convincing these brands to

switch to more environmental benign DWR alternatives that do not release long chain

PFAAs. Presently available DWR raw materials are therefore either based on short chain-

SFPs (with CnF2n+1-R and n£ 6 described as s-SFPs in this work) or non-fluorinated

chemistry.

This chemical substitution in consumer textiles, however, took place before alternatives

were sufficiently characterised for human health and environmental effects31 and tech-

nical performance profiles. The s-SFPs still utilize the structural principles of the l-SFPs

while substituting the long perfluoroalkyl side chains with shorter ones. In addition to the

s-SFP-based DWR products, the current market is characterized by a growing number of

non-fluorinated DWR-products often marketed through assurances of good technical per-

formance and benign environmental fate.


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1.1 The SUPFES project-how Academia and Industry work together

The four-year multidisciplinary venture “Substitution in Practice of Prioritized Fluorinated

Chemicals to Eliminate Diffuse Sources” (SUPFES) aims to characterize and decrease

the diffuse emissions of PFASs and other priority environmental pollutants in consumer

textiles. The different research groups and core competences are illustrated in Figure 2.

As can been seen from the figure, the four organizations conducting the research in the

project are the academic institutions of Vrije University (VU) Amsterdam in the Nether-

lands, Stockholm University (SU) and Chalmers University, and the textile research insti-

tute Swerea IVF. Multiple stakeholders are also closely involved in the SUPFES project,

namely; governmental authorities (e.g. the Swedish Chemicals Agency (KEMI)), the fluo-

rochemical manufactures (e.g. 3M and Chemours), textile producers (e.g. Haglöfs) and

nongovernmental organizations (NGOs, e.g. the Swedish Society for Nature Conserva-

tion). The collaboration with industrial stakeholders has made it possible to generate ex-

periments on DWR-polymers that are similar to those used in the textile industry.

Figure 2: Schematic representation of the international consortium that carry out the research in the SUP-FES project and their different core competences. Researchers in academia work together with the textile research institute, Swerea IVF. The figure also illustrates the importance of stakeholder involvement.

The aims of the project are31 to: i) characterize the diffuse emissions of critical environ-

mental pollutants (e.g. PFAAs but also cyclic siloxanes like D4 (octamethylcyclotetrasilox-

ane) and D5 (decamethylcyclopentasiloxane) from consumer products such as textiles,

and ii) compare the a) technical performance and b) environmental impacts of alternative


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DWRs to those based on l-SFPs. The goal is to help industry find DWR alternatives that

can provide technical performance and at the same time be environmentally benign. SUP-

FES also intends to provide policy makers with a basis for legislation and industry with

guidelines for ensuring reduced human health and environmental impacts31.

1.2 Textile repellency

Textile’s repellency is a property that often stays unnoticed until it starts raining or other

liquids gets spilled over a fabric’s surface. Modern fabrics consist of complex fiber assem-

blies32 with open pores and a surface structure defined by the woven yarns and different

fabric constructions. Therefore, the interaction of liquids and with textile surfaces is a

complex process and different wetting phenomena can be observed on these non-ideal

surfaces (see Figure 3 a3-a5).

For an effective substitution of chemicals related to functionality of DWRs, it is beneficial

to understand the repellency of textiles at a macro and microscopic scale. Repellency is

defined as a condition of limited wettability9. The interaction of liquids and textiles33 de-

pends mainly on their fiber geometry, the capillary geometry (pores between the fibrous

assemblies), the amount and chemical nature of the liquid and the wettability of the fibers.

The latter can be influenced by the DWR coating (see Figure 3a). When it comes to pro-

tection under heavy weather conditions, the production of efficient water repellent fabrics

is of great practical importance34. Regardless if water droplet are falling in a cloud burst35

(with high hydrostatic pressure average droplet diameter ~0,3 mm; terminal velocity ~25

km/h and EKinetic ~346 x 10-6 Nm per droplet) or as drizzle35 (with much lower kinetic en-

ergy droplet diameter ~0,02 mm; terminal velocity ~3 km/h and EKinetic 0.0012 x 10-6 Nm

per droplet) on textiles, a droplet deposited on an optimal DWR-treatment will form high

contact angles (CA) and will roll off easily from the garments. Figure 3 shows an example

of a typical layered fabric construction10 of high performance rain gear that consist of a

water repellent fabric with DWR-treatments (see Figure 3 a), a waterproof membrane

(see Figure 3b) and an a inner fabric (see Figure 3c) that holds the different materials

together and stabilizes the waterproof membrane. The single fibers in the outer fabric are

coated with DWR-polymers (see Paper I and II) and these chemical moieties (see Figure

3a1) form an “umbrella-like” hydrophobic shield which transfers the woven fabric into a

surface near to the superhydrophobic state36 (surfaces with water contact angles of qw

>150°).


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Figure 3: Schematic representation of a layered waterproof and breathable fabric (simplified) and its moisture reg-ulation through the fabric with: (a) an external fabric that consists of a woven fiber material that is (a1) coated with a crosslinked DWR-polymers containing different hydrophobic moieties and ideally results in textiles that show “Cas-sie-Baxter” like liquid repellency. This optimal repellency can be reduced by high hydrodynamic pressure and/or an inefficient DWR-treatment that results in a reduced repellency of (a3) the “Wenzel state” or (a4) in the worst case a complete wet-out is caused by the liquid’s penetration into the pores of the weave called “wicking” and (b) a porous membrane based on stretched PTFE or membranes with hydrophilic channels that are stabilized through (c) an inner fabric. Due to the combination of hydrophobic fibers and a rough surface of fibrous assemblies,

water droplets minimize their contact area (and surface free energy37) to the textile sur-

face resulting in the “Lotus-like” Cassie-Baxter wetting38 (Figure 3 a2) with air trapped

below the drop. This causes consequently a very low adhesion and water droplets are

easily repelled without leaving water films between the fibers. If the DWR treatment has

reduced efficiency or the hydrostatic pleasure increases (e.g. water waves crashing over

a boot during sailing), water wet the fabric surfaces according to the Wenzel state39,

where water droplets form high CA but are pinned to the fabrics (see Figure 3 a3) and

therefore not easily repelled. Outdoor garments with this behavior would still be repellent,

since the water would not penetrate into the pores of the weave but the user could sense

a difference in the macroscopic repellency. If the DWR treatment is insufficient, water

droplets wet the woven fabrics completely, a phenomenon called “wicking”33 (Figure 3 a4)

resulting in a wet-out (the outer fabric absorbs water). Even if wet out occurs, the mem-

brane offers another barrier towards water. The complete wetting of the outer fabric, how-

ever, can cause a significant cooling of the wearer and a “wet feeling” due to a thermal

bridges caused by water.

The best results for DWR-treatments have been achieved with comb-like polymers based

on l-SFPs (with side changes based on CnF2n+1¾R with n=8 see Figure 1)40 and the


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switch to short chains s-SFPs showed a reduced textile repellency, at least in early prod-

ucts41.

Even more challenging is to create textile repellency against liquids that differ from water

in their polarity and surface tension such as biological fluids or oily stains35. Liquids with

lower polarity and consequently lower surface tension are not so easily repelled by textile

fabrics. This is particularly important when it comes to technical protective clothing where

DWRs deliver a lifesaving functionality (see Figure 7).

1.3 Aims and objectives of the thesis.

1) Identification of the main data gaps for currently used DWRs for textile applications

with regards to their, structure property relationships, technical performance and envi-

ronmental fate (Paper I).

2) Provide a comprehensive technical performance screening of relevant alternative

DWRs in comparison to l-SFPs (Paper II).

3) Describe the future research directions within this doctoral project.


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2. Summary of papers

2.1 Paper I: Properties, performance and associated hazards of state-of-the-art du-rable water repellent (DWR) chemistry for textile finishing

Background

This critical review combines the identification and description of alternative DWR chem-

istry and the characterization of the hazards associated31 with chemicals likely to be dif-

fusely released from these DWR-treatments. Emissions are expected to occur via two

possible pathways; (I) the leaching of impurities from chemical production that are not

bound to the fabric fiber and (II) gradual degradation of DWR-treated products during the

use-phase and degradation of fiber fragments or particles lost from woven fabrics by me-

chanical stress. The paper also identified major data gaps when it comes to the environ-

mental behavior of DWR-polymers.

Methods

Figure 4: Schematic representation of the approach to (a) identify alternative DWR chemistry, (b) esti-mate the emissions of chemicals and (c) the hazard assessment related to these chemicals. Since DWRs are of high commercial interest, the molecular structure is often a trade se-

cret and only a limited amount of open access literature describes the presently used

DWR-chemistry in detail. Therefore, other non-conventional sources (e.g. the patent lit-

erature, interviews with industry) were used for obtaining relevant information


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Results

The review of different accessible sources (see Figure 4) showed that DWR alternatives can be divided into four broad groups that reflect their basic chemistry: side-chain fluori-nated polymers, silicones and hydrocarbons that represent the hydrophobic moieties. These moieties are bonded to a polymer backbone that allows the formation of a DWR-film on the individual fibres of the fabrics. The fourth group referred to as “other chemis-tries” in the paper is based on the same hydrophobic moieties that are bound to organic or inorganic particles (includes dendrimer and inorganic nanoparticle chemistries). Struc-tures of modern DWR-polymers are often copolymerized with hydrophilic segments that deliver certain fibre affinity or solubility of the emulsions. The results showed that there are large differences in performance between the alternative DWRs, most importantly the lack of oil repellency of non-fluorinated alternatives.

The results also showed that for all alternatives, impurities and/or degradation products of the DWR chemistries are diffusively emitted to the environment. The pathways of criti-cal chemicals into the environment are complex and can occur (I) during the textile finish-ing process in the textile mills (II) during the use phase, due to wear and tear (III) after disposal (e.g. in landfills) or incomplete combustion processes. An example of loss pro-cesses that can occur during the use-phase of textiles which have been treated with l-SFPs is the release of PFOA (and higher homologues), which is portrayed in Figure 5. Textiles with alternative DWRs will undergo comparable loss processes resulting in the release of a wide variety of different substances, depending on the initial chemistry. Nev-ertheless, the loss during finishing and after disposal of textiles will differ widely and to foresee it requires a deeper understanding of these processes.

Our hazard ranking suggests that hydrocarbon-based DWRs are the most environmen-

tally benign, followed by silicones and the side-chain fluorinated polymer-based DWR

chemistries. Industrial commitments to reduce the levels of impurities in silicone based

and side-chain fluorinated polymer based DWR formulations will lower the actual risks.

Furthermore, the following major data gaps were identified and will be addressed through-

out the future work within the SUPFES project.

1. Some alternative DWRs showed improved hazardous properties compared to legacy

l-SFP DWRs, but up until now it is unclear to what extent environmentally benign alter-

natives can be used to meet the different user needs and fulfil certain technical perfor-

mance criteria.

2. A number of data gaps were identified in the hazard assessment, especially for the

degradation products of the silicone DWRs. The group of “other chemistries”, including

dendrimers and inorganic nanoparticles, was not possible to characterize at all due to

the lack of information on these structures.

3. The relevance of the loss scenarios needs to quantified with environmentally realistic

experiments.


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Figure 5: Possible mechanisms (simplified) for loss of (g) PFOA from DWR treated fabrics during (II) the use phase for the example of DWRs based on long-chain C8 PFASs with (a) cleavage of the polymer backbone by UV-light into oligomeric/polymers, (b1) the evaporation of the 8:2 FTOH as residual from the fabric, (b2) the transformation of 8:2 FTOH in the atmosphere into PFOA, (b3) the rain-out of water soluble PFOA from the atmosphere, (c) the wash-out of water soluble residuals like PFOA or water soluble monomers, (d1) the loss of particles and fibre fragments caused by abrasion containing the C8 side-chain fluorinated polymer based DWR treatment which might undergo further degradation processes (d2) in the environment, (e) the hydrolysis of C8-side chain during laundering and the loss of DWR-coated fibre fragments during the washing process into the effluent, (f) the release of DWR-coated fibre fragments via the wastewater treatment plant and the further transformations of these precursors in PFOA


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2.2 Paper II: Performance evaluation of state-of-the-art durable water repellents for PA and PES fabrics.

Background

Paper 2 provides an overview of the technical performance of currently available fluori-

nated and non-fluorinated alternative DWR technologies for textiles which were identi-

fied in paper 1.

Method

Figure 6: Schematic representation of the SUPFES approach for the DWR-selection process and experi-mental setup with (a) the identification of state-of-the-art DWR-chemistry (b) grouping of the formulations into side-chain fluorinated polymers (SFPs), silicones (Sis) and hydrocarbons (HCs) and (c) the DWR se-lection that involved consultation with major raw material suppliers including nondisclosure agreements (NDAs)

DWRs were grouped in this study according to their ability to provide water (and oil) re-

pellency (see Figure 6b) and according to their expected environmental fate. DWRs

were applied and tested for repellency using industrial standard and complementary

methods. Since the repellency and durability over the garment’s lifetime strongly de-

pends on the choice of DWR-formulation, curing conditions, industrial expertise and em-

pirical trials, the SUPFES approach has been to work closely with major raw material

suppliers. This collaboration has made it possible to apply the DWR-polymers in a way

that was similar to those used in the textile industry under industrial conditions.


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Results

Most short-chain SFPs and non-fluorinated DWRs showed excellent water repellence

and durability while short-chain SFPs were the more robust technology. A strong de-

cline in oil repellency with perfluoroalkyl chain length was determined for fluorinated

DWRs. Non-fluorinated alternatives did not repel oil at all.


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3. Discussion

Through the collaboration within the SUPFES project and the critical review paper (paper

I) about alternative DWRs for textile applications, major data gaps could be identified that

limit the complete evaluation necessary to substitute l-SFPs with environmentally benign

alternatives. Indeed, it is questionable if a certain DWR-technology should be favored

over another one based on current knowledge as such a decision requires a comprehen-

sive understanding of properties and environmental behavior of DWR-polymers. This ap-

plies for their technical performance (paper II) as well was for their environmental behav-

iour (paper I). Although most alternatives DWRs have a favourable hazard profile com-

pared to legacy l-SFPs (see paper I), they all release impurities and/or degradation prod-

ucts into the environment and the precise characterization of the complex loss processes

(see paper I section 4) has not been conducted. Although “prominent” examples of long-

chain perfluoroalkyl acids like PFOA are found and extracted in textiles in several stud-

ies,42,20,43 loss scenarios for technical DWR-polymers (see Figure 1) are likely to result in

complex precursors including particles, fibre fragments or oligomeric breakdown prod-

ucts. This release of large molecules and particles could result from material stress during

the use-phase of textiles and once released into the environment could slowly degrade

to release, for example, more PFAAs. In addition, the production of textiles during the

fibre treatment process could be another source of environmental pollutants21 when run

under inadequate process conditions. Last but not least, the disposal of textiles could be

important for the fate of DWR-finishes. Both waste incineration44 and disposal in landfills45

seem to be not unproblematic for fluorinated materials given their extreme resistance to

degradation.

All these aspects should be considered when assessing DWR alternatives for their long

and short term environmental impacts. Particular attention should be given to DWR alter-

natives that release persistent and/or toxic compounds. For example, the s-SFPs, which

are currently the material of choice when it comes to high performance applications46 (see

paper II) can release precursors that will degrade into perfluorobutane sulfonic acid (PFBS) and perfluorohexanoic acid47 (PFHxA). These substances have, similar to their

higher homologues (PFOA and PFOS), negligible environmental degradation half lifes48,

49 and environmental concentrations will likely rise and be difficult to reverse50. This argu-

ment might also be true for impurities released from other DWR alternatives such as cyclic

siloxanes that have high degradation half-lives in certain environmental media51 (e.g. in

aquatic sediments).

Furthermore, it is still unclear if textiles with DWR-treatments are a major source of envi-

ronmental pollutants like PFAAs and no systematic studies have been presented so far20.


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Nevertheless, consumer outdoors textiles (estimated with 23 billion USD in sales for

201852) are produced for a mass market and the global production of SFPs was roughly

estimated by Knepper et al. at 15,000 tonnes per year20 (~10% of the total fluoropolymer

production). Considering these high production estimates, the identified loss scenarios

from DWR treated textiles (paper I) and the fact that industrial processes sometimes

might not run under optimal conditions53 (e.g. bad curing conditions), defuse emissions

caused by functional textiles should be a topic of further investigation.

Experiments are necessary to quantify loss processes under realistic conditions and help

to estimate total emissions. This quantification needs to be combined with a mechanistic

explanation of the loss processes identified in paper I. Determining the breakdown of

SFPs with analytical methods is challenging since technical DWR-products consist of

complex polymers structures with a distribution of molecular weight. Furthermore, a good

quantification of emissions needs a deep understanding of production conditions and con-

sumer behaviour including disposal scenarios. In particular, conditions during the produc-

tion of consumer textiles at the fibre finishing process are often hard to assess. The con-

stellation of industrial stakeholders which are part of the SUPFES-project (see Figure 2)

should help to base our further research on realistic assumptions, if they are willing to

provide us with the necessary information.

Another perspective on a successful substitution of l-SFPs with alternative DWRs could

consider consumer needs. DWR-finishes (as shown in Figure 7, published as Fig. 3 in

paper I) have to fulfil a broad range of performance requirements depending on their end-

use. The figure opens up the hypothesis that not all textiles necessarily need the highest liquid repellency. The investigations of paper II showed an excellent in the technical per-

formance of non-fluorinated alternative DWRs in some applications. Since “the overlap

between outdoor, active wear, and lifestyle dressing is increasingly muddled”54 it might

be reasonable to reconsider where s-SFPs deliver essential functionalities and where

environmental begin alternatives are suitable substitutes for l-SFPs.


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Figure 7: Illustration of the increased need for technical performance (here in essence degree of oil repel-lency and durability of oil- and water repellency) with more advanced user needs; advancing from fashion to comfort to hazard management. Examples of garments meeting user needs within the fashion segment are e.g. jackets primarily chosen based on looks (design, colour etc.) and never or seldom used in weather conditions requiring water repellency. Garments within the comfort segment could be e.g. jackets often used in weather conditions requiring water repellence to stay warm and dry but where the user can find shelter within a reasonable time and thus is unlikely to experience a life threatening situation due to failing water repellency. Finally, garments in the hazard management segment must be water (and sometimes oil) repellent for protecting the life of the wearer. Garment types (A–H) were subjectively placed in the graph and further work is needed to quantify the metrics on the graph's axes


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4. Future work Future research within this doctoral project in cooperation with the other SUPFES mem-

bers will include a broad environmental assessment (i.e. risk and life cycle assessment

(LCA)). This work will be led by the colleagues at Chalmers University (see Figure 2). So

far we have only considered impacts from emissions during the use phase. Further inves-

tigations within the SUPFES project will focus on the environmental fate and effects of

chemicals released from alternative DWRs during their entire life cycle. This will include

(I) production during the fiber treatment process, (II) additional releases during the use-

phase from wear and tear and (III) releases after disposal which will include incineration,

the transfer to landfills and sewage sludge applied to agricultural land.

Project I: “Strategies for replacing persistent polymers in textile finishing based on the consumer perspective”. This study aims to further evaluate the potential of non-fluorinated

DWRs by readdressing consumer needs and technical functionality in DWR outdoor ap-

parel. For this purpose, SU will cooperate with researchers of the University of Leeds who

collect data to evaluate the consumer needs in relation to different outdoor clothing seg-

ments that use DWR-treatments (see Figure 3 D-H). Results of this survey will be com-

bined with data from practical experiments conducted at the textile research institute

Swerea IVF (see Figure 2). The results of paper II showed some encouraging water re-

pellency and durability results for alternative non-fluorinated DWRs, but non-fluorinated

DWRs did not repel oil. While the oil repellence (ISO 14419) is tested using different non-

polar oils with a very low surface tension (see methods in paper II), the majority of stains

can be repelled more easily by textile surfaces (see 1.2) since they do not contain a large

amount of lipids (e.g. coffee; red wines) which results in their intermediate polarity and

higher surface tension values. Some preliminary experiments with non-fluorinated DWR-

polymers that were optimized by one of SUPFES’s industrial stakeholders to stain repel-

lency of the PA and PES fabrics (see materials paper II) showed promising first results

with liquids of intermediate polarity. Additional first results from the consumer survey in-

dicated that stain repellency might be not a major criterion for purchasing an outdoor

garment. This project will critically evaluate where the highest technical performance of

fluorinated DWRs in consumer textiles are needed and where environmental benign ma-

terials could deliver alternative solutions.


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Project II: “Determining emissions from textiles containing durable water repellents based on side chain fluorinated polymers”. This study will quantify and characterize total

emissions from with DWR-treated fabrics (based on l- and s-SFPs). A high number of

fabrics (³ 10 replicates) with DWR-treatment will be exposed to stressors like washing,

weathering (artificial and real weathering test in Australia with exposure to a broad-spec-

trum UV radiation of up to 1kW/m2) and abrasions, to simulate a garments life length.

Emissions will be quantified using Combustion Ion Chromatography (CIC) at SU and by

using Particle Induced Gamma-ray Emission (PIGE) in cooperation with the Oregon State

University. Both methods will determine the total loss of organofluorine before and after

application of combined stress parameters to the fabrics treated with l- and s-SFPs. Pre-

liminary experiments conducted by researchers at VU Amsterdam (see Figure 2) indicate

that the DWR-coating applied to the fabrics in a discontinuous padding process (see

methods in Paper II) is relatively evenly distributed over the fabric, which is an important

condition to determine loss processes. Until now, it is unclear if the available methods are

sensitive enough to measure the differences in fluorine losses and make precise emission

estimates. Nevertheless, reduction of the macroscopic repellency (seen e.g. in Figure 7

in paper II) is an indication that major changes happen to the textile surfaces during the

durability tests.

Project III: “A mechanistic study of emissions caused by gradual degradation processes of Textiles with SFPs” This mechanistic study of the “visual” (microscopic) changes of the

fibre surface (see Figure 3) after applying mechanical stress like the Martindale abrasion

test (see methods paper II) will be conducted with scanning electron microscopy (SEM)

at the textile research institute Swerea IVF. A more advanced analysis of the degradation

processes of SFP-based DWRs with the help of high resolution mass spectrometry could

be an approach for an improved mechanistic understanding of gradual degradation pro-

cesses. Since mobile, non-volatile breakdown products of SFPs will have a high affinity

to the surface of the remaining DWR-coating on the fibres (due to fluorophobic interac-

tions55 similar to process that occur during side chain crystalisation56), it might be possible

to extract and analyze more complex precursors of PFAAs. This method could confirm

the presence of the predicted degradation products from loss processes identified in pa-

per I. A similar approach was already used by Soeriyadi at all57 to study the degradation

behavior of acrylic model polymers (poly(hexafluoro butyl methacrylate)) exposed to tem-

perature and UV-light on a molecular level. The identification of gradual degradation (e.g.

oligomers) products could result in a better understanding of loss processes from con-

sumer textiles and be a complementary method to the targeted analysis of textiles con-

ducted at VU-Amsterdam.


18

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