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The missing links: Towards an Informed Substitution of Durable Water Repellent Chemicals for Textiles
Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Durable water repellents (DWRs) that provide liquid repellency to functional textiles are part of an ongoing global substitution process. The process of substitution was initiated after DWRs based on side-chain fluorinated polymers (long-chain SFPs) were identified to contribute to the diffuse release of long-chain perfluoroalkyl acids (PFAAs) to the environment. Long-chain PFAAs are organic contaminants that are extremely environmentally persistent, have a propensity to bioaccumulate, and are toxic to wildlife and humans. This thesis aims to support the substitution process by identifying alternative DWRs that combine functionality with a benign environmental profile. As part of the SUPFES project, a cooperation between academic and industrial research groups, several studies were conducted in a three-step approach to form a basis for an informed substitution process. This approach included practical tests of functionality (STEP 1) of DWR alternatives in different textile applications, experimental work and desk-based review of the literature to determine 13 hazard endpoints (STEP 2) and life cycle assessment (STEP 3). DWR alternatives were grouped into short-chain SFPs, silicones (Sis) and hydrocarbons (HCs). To profile their environmental behaviour, potential loss mechanisms that cause the release of critical (i.e. potentially hazardous) chemicals were estimated and confirmed experimentally.

The results showed that no DWR substitute provided a universal solution considering functionality (STEP 1) and the associated chemical hazard together (STEP 2). Short-chain SFPs exhibit high durabilities and repellency of liquids of all different polarities, but lead to the release of extremely persistent short-chain PFAAs. Some HCs are more environmentally benign in terms of human health and ecological risk, and show a high water repellency as well as durability, but do not repel liquids with very low surface tension. Thus, we suggest to choose DWR alternatives according to specific protection needs that are required in different segments of the textile market. For consumer outdoor clothing, that mainly require water repellency, a trade-off by using more environmentally friendly materials which do not offer complete stain repellency could be made. For other textile segments, such as protective work clothing, where no compromise of safety is possible, short-chain SFP substitutes are today the only viable option.

The loss of textile fibres from functional textiles and the degradation of the fibre-bound DWR coatings after their emission was identified to be a loss mechanism that leads to the long-term release of persistent contaminants. Fibre loss of short-chain SFP containing textiles, due to domestic washing, was characterised for size and amount as well as their total fluorine content. Results showed that the fibres lost can still contain the fluorinated DWR coatings and likely form a long-term emission source of PFAAs through their accumulation and slow degradation in the environment. These results provide further information for the life cycle assessment (LCA) (STEP 3).

The expected long-term environmental release of extremely persistent short-chain PFAAs, suggests that DWRs based on SFPs are not a sustainable substitution solution. Therefore, new concepts in textile technology are needed for a complete substitution of fluorinated DWRs. Our stepwise approach generates useful data to make an informed judgment about possible DWR alternatives and will together with the LCA provide much needed guidance in the substitution process.

Place, publisher, year, edition, pages
Stockholm: Department of Environmental Science and Analytical Chemistry, Stockholm University , 2019. , p. 53
National Category
Earth and Related Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
URN: urn:nbn:se:su:diva-168250ISBN: 978-91-7797-680-6 (print)ISBN: 978-91-7797-681-3 (electronic)OAI: oai:DiVA.org:su-168250DiVA, id: diva2:1307443
Public defence
2019-06-13, De Geersalen, Geovetenskapens husSvante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

Available from: 2019-05-21 Created: 2019-04-26 Last updated: 2019-05-14Bibliographically approved
List of papers
1. Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing
Open this publication in new window or tab >>Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing
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2016 (English)In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 91, p. 251-264Article, review/survey (Refereed) Published
Abstract [en]

Following the phase-out of long-chain per- and polyfluoroalkyl substances (PFASs), the textile industry had to find alternatives for side-chain fluorinated polymer based durable water repellent (DWR) chemistries that incorporated long perfluoroalkyl side chains. This phase-out and subsequent substitution with alternatives has resulted in a market where both fluorinated and non-fluorinated DWRs are available. These DWR alternatives can be divided into four broad groups that reflect their basic chemistry: side-chain fluorinated polymers, silicones, hydrocarbons and other chemistries (including dendrimer and inorganic nanoparticle chemistries). In this critical review, the alternative DWRs are assessed with regard to their structural properties and connected performance, loss and degradation processes resulting in diffuse environmental emissions, and hazard profiles for selected emitted substances. Our review shows that there are large differences in performance between the alternative DWRs, most importantly the lack of oil repellency of non-fluorinated alternatives. It also shows that for all alternatives, impurities and / or degradation products of the DWR chemistries are diffusively emitted to the environment. Our hazard ranking suggests that hydrocarbon based DWR is the most environmentally benign, followed by silicone and 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. There is a lack of information on the hazards associated with DWRs, in particular for the dendrimer and inorganic nanoparticle chemistries, and these data gaps must be filled. Until environmentally safe alternatives, which provide the required performance, are available our recommendation is to choose DWR chemistry on a case-by-case basis, always weighing the benefits connected to increased performance against the risks to the environment and human health.

Keywords
Hazard assessment, Per- and polyfluoroalkyl substances, PFAS, Silicones, Wax, Dendrimers
National Category
Earth and Related Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-131212 (URN)10.1016/j.envint.2016.02.035 (DOI)000375630500026 ()26994426 (PubMedID)
Available from: 2016-06-14 Created: 2016-06-14 Last updated: 2019-04-30Bibliographically approved
2. Facing the rain after the phase out: Performance evaluation of alternative fluorinated and non-fluorinated durable water repellents for outdoor fabrics
Open this publication in new window or tab >>Facing the rain after the phase out: Performance evaluation of alternative fluorinated and non-fluorinated durable water repellents for outdoor fabrics
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2018 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 193, p. 675-684Article in journal (Refereed) Published
Abstract [en]

Fluorinated durable water repellent (DWR) agents are used to obtain water and stain repellent textiles. Due to the on-going phase-out of DWRs based on side-chain fluorinated polymers (SFP) with long perfluoroalkyl chains, the textile industry lacks suitable alternatives with comparable material characteristics. The constant development and optimization of SFPs for textile applications initiated more than half a century ago has resulted in a robust and very efficient DWR technology and textiles with exceptional hydro- and oleophobic properties. The industry is now in the predicament that the long-chain SFPs with the best technical performance have undesirable toxicological and environmental behavior. This study provides a comprehensive overview of the technical performance of presently available fluorinated and non-fluorinated DWRs as part of a chemical alternatives assessment (CAA). The results are based on a study with synthetic outdoor fabrics treated with alternative DWRs and tested for repellency using industrial standard and complementary methods. Using this approach, the complex structure-property relationships of DWR polymers could be explained on a molecular level. Both short chain SFPs and non-fluorinated DWRs showed excellent water repellency and durability in some cases while short-chain SFPs were more robust of the alternatives to long-chain SFPs. A strong decline in oil repellency and durability with perfluoroalkyl chain length was shown for SFP DWRs. Non-fluorinated alternatives

Keywords
Chemical alternatives assessment, Per- and polyfluoroalkyl substances outdoor apparel, Water repellency, Oil repellency, Sustainability
National Category
Earth and Related Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-153653 (URN)10.1016/j.chemosphere.2017.11.027 (DOI)000423890500080 ()29172158 (PubMedID)
Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2019-04-30Bibliographically approved
3. Highly fluorinated chemicals in functional textiles can be replaced by re-evaluating liquid repellency and end-user requirements
Open this publication in new window or tab >>Highly fluorinated chemicals in functional textiles can be replaced by re-evaluating liquid repellency and end-user requirements
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2019 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 217, p. 134-143Article in journal (Refereed) Published
Abstract [en]

Ongoing regulation of, and concerns regarding, polyfluoroalkyl substances (also popularly known as highly fluorinated chemicals), has the textile market to search for sustainable alternative chemistries that can provide similar liquid repellency to polyfluoroalkyl substances in performance textiles. This paper aims to inform the potential substitution of fluorochemicals with more environmentally friendly durable water repellents, taking a case-by-case approach and evaluating protection needs for consumer outdoor clothing and protective clothing separately. Recently developed non-fluorinated durable water repellents, some based on green chemistry principles, were evaluated in an in depth assessment for their functionality against fluorinated short-chain alternatives (with hydro- and oleophobic moieties of carbon chain length or six or less). Repellency towards water and non-polar liquids was evaluated with established standard test methods and at measuring the roll-off angle of liquid droplets with a novel sample holder setup. This improved method allows an enhanced mechanistic understanding of the droplets' roll-off processes on woven textiles. The best non-fluorinated alternatives are high water repellency equal to fluorinated side-chain polymers with short fluorinated carbon chains, and should be considered as suitable substitutes for consumer outdoor clothing. These results are supported by a survey of end-use requirements indicating water repellency and durability were the most important purchasing criteria. For polar liquids, with lower surface tensions, the repellency provided by non-fluorinated alternatives was clearly reduced, although they had a moderate repellency towards liquids with intermediate polarity (eg red wine or synthetic blood). Only fluorinated side-chain polymers with "short" fluorinated carbon chains <= 6 carbons were provided to provide sufficient protection to polar liquids with very low surface tension (olive oil or gastric fluid). Since occupational protective clothing (eg medical clothing) often must provide protection against liquid of a wider range of polarities (eg in the case of medical clothing, to bodily fluids and protect the wearer from the transmission of diseases, current non-Fluorinated DWRs do not provide sufficient liquid repellency. This means that innovations in textile technology are still needed to substitute PFASs in some types of occupational protective clothing and other end uses where oil and stain repellency is essential.

Keywords
PFAS, Roll-off angle, Medical, Outdoor, Apparel, Water repellent, Green & Sustainable Science & Technology
National Category
Earth and Related Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-167557 (URN)10.1016/j.jclepro.2019.01.160 (DOI)000461410100013 ()
Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-04-30Bibliographically approved
4. Release of side-chain fluorinated polymer-containing microplastic fibers from functional textiles during washing and first estimates of perfluoroalkyl acid emissions
Open this publication in new window or tab >>Release of side-chain fluorinated polymer-containing microplastic fibers from functional textiles during washing and first estimates of perfluoroalkyl acid emissions
Show others...
(English)In: Article in journal (Refereed) Submitted
National Category
Earth and Related Environmental Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-168247 (URN)
Available from: 2019-04-26 Created: 2019-04-26 Last updated: 2019-04-30Bibliographically approved

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