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Title: Liquid repellent finishing in outdoor apparel : chemical management, environmental concerns and performance testing
Author: Hill, Philippa Juliet
ISNI:       0000 0004 7964 4051
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2019
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Liquid repellency is a key textile function for outdoor apparel. Chemistry based on long side-chain fluorinated polymers has been used for repellent textile finishing since the 1950s but in the last two decades has been significantly highlighted for its toxicological potential. This study addresses the move to shorter side-chain fluorinated polymers and non-fluorinated chemistries for repellent finishing specifically addressing the requirements in technical outdoor apparel. In light of the complexities between functionality, legislation and corporate social responsibility, this research has investigated consumer practises and requirements in relation to, and comparison of, the technical performance of long side-chain fluorinated Durable Water Repellents (DWRs), shorter side-chain fluorinated DWRs and non-fluorinated DWRs. A comparative study on initial repellency functionality showed non-fluorinated DWRs to be inferior in terms of oil repellency but offering similar water repellency. The impact of consumer laundering was studied with a comparison on the influence of differing drying/heat applications. Differences in maintaining liquid repellency functionality of fluorinated and non-fluorinated DWRs, during consumer laundering, have been discussed with surface mechanisms influencing this explained. This work has identified limitations with the standard spray test method and given modifications to quantify between similar performing repellent fabrics. Calculation of mass increase, calculated after the spray test shower, has been used throughout this work to quantify the wetting of samples. In addition, the use of analytical evaluation by determining the roll-off angle during dynamic wetting has been considered. A comparative study between the spray test and the Bundesmann ran-shower test was carried out but water repellency data differed between the two methods. An extended spray test has been developed to aid discrimination between similarly performing water repellent samples, with a shower time of 60 and 120 minutes recommended. Adaptations to the Martindale test method simulated abrasion to terrain and adjacent apparel replicating rubbing of the face fabric during consumer end-use. The repeated rubbing created roughness of the fabric face decreasing the repellent functionality. The relationship between DWRs and thermoregulation has been explored and greater heat loss during rain conditions determined with a build-up of moisture vapour due to a decreased driving force across the outer shell. Further work in this area is strongly recommended. The main conclusions from this work are to reconsider the use of DWRs and the level of functionality necessary for end-use, the importance of laundering to maintain functionality and the necessity to develop knowledge and communication between brands and consumers. It is hoped that this work has contributed to the ongoing dialogue surrounding chemistry use for liquid repellent textile finishing and will be useful to testing and adoption as, in line with legislation, the move to non-fluorinated DWRs increases.
Supervisor: Blackburn, Richard ; Taylor, Mark Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available