Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Dyeing has an influence on the characteristic properties of wool fibres. This can result in changes in the final properties of the fibre including fibre elasticity, fibre strength and breaking elongation of the wool fibres, especially in the case of dark colours. Damage that occurs to the fibre surface due to the action of acid, alkali, dyestuff, water, heat, and mechanical stress during the dyeing process can thus have an affect on the fibre breaking elongation and the fibre strength. The aim of this project was to assess the effect of dyeing with different colours (ranging from light to dark) on the surface of wool fibres using atomic force microscopy (AFM). The results indicated that four different types of surface damage can be discerned: scale raising, scale chipping, fluting and pitting. The findings also indicate that the surface damage to the fibres was greater and more noticeable (especially the scale raising) on fibres dyed with dark colours than to fibres dyed with light colours. The same applied to the fibre strength and elongation, where generally the fibre breaking extension and the breaking load was smaller in the case of darker colours. The effect of dyeing with different colour shades on the fibre surface was observed with AFM. Several characteristic scale parameters of a statistical significant number of dyed and undyed fibres were measured in order to determine the surface damage caused by dyeing. The correlation between the surface damage, observed by AFM, and the loss in tensile strength and fibre elongation, determined by tensile tests, were investigated. This was done in order to determine the effect of the cuticle damage on the tensile stress/strain behaviour. The results show that AFM is a viable tool to study the effects of different dyes on the fibre surface and for detecting surface modifications with great accuracy. It was found that dyeing with dark colours caused greater damage to the surface than light colours, and it was possible to distinguish different lightness areas, which could be regarded as light and dark colours.

Textilindustrin har under de senaste åren vidtagit drastiska åtgärder för att ställa om till en mer hållbar industri och därav möta målen för Agenda 2030. Denna undersökning syftar till att förbättra den resurssnåla hydrauliska sprayteknikens infärgning på ullvävar med hjälp av två resurssnåla förbehandlingar, plasmateknologi och ultraljudsbad. Färgklasser som används är syrafärg och reaktivfärg. Efter litteratursökning har försök utfärdats för att optimera de båda metoderna med ändamål att en mer intensiv och jämnt fördelad färg ska framträda. Inställningar gällande både ultraljudsbehandlingen och plasmateknologin diskuteras såväl som möjligheten till att effektivisera färgrecepten. Resultaten presenteras efter utförda tester på vätbarhet och färgmätningar innefattandes färgförändring och färgstyrka. Underlagen för signifikanta skillnader är bristfälliga men vissa tendenser på förbättring gällande alla avseenden kan urskiljas, dock utan slutsats om optimala inställningar. Bäst effekt återfinns i färgstyrkan för båda behandlingarna oavsett färgklass. Tas däremot alla tester i beaktande dras slutsatsen att plasmabehandlingen bäst möter de optimala egenskaperna som ullvävarna bör anta för en godtagbar infärgning. Vätbarhet, som syftar till materialets hydrofilitet, visar på betydligt bättre resultat för de plasmabehandlade proverna än för ultraljudsbehandlade, dock inte i den mån för att tillgodose problemet. Trots detta har de båda förbehandlingarna potential till att uppfylla syftet med studien, men ytterligare forskning och vidare tester krävs för att kunna implementera dessa i industrin. / In recent years, the textile industry has taken drastic measures to transition to a more sustainable industry and thus meet the goals of the 2030 Agenda. This study aims to improve the resource efficient hydraulic spray dyeing technique on wool fabrics using two resource efficient pretreatments: plasma technology and ultrasonic bath. The dyes used are acid dyes and reactive dyes. After a literature review, lab tests have been conducted to optimize both methods with the aim of producing a more intense and evenly distributed colour. The settings of both the ultrasonic and the plasma treatment are discussed as well as the possibility of streamlining the colour recipes. The results are presented after performing wettability tests and colour measurements including colour change and colour strength. There is no evidence for significant differences but tendencies for improvement in all aspects can be differenciated, however without a conclusion on optimal settings. The best effect is found in regards the colour strength for both treatments irrespective of dye class. However, if all tests are taken into account, it can be concluded that the plasma treatment meets the optimum properties that wool fabrics should adopt for an acceptable dyeing. Wettability, which refers to the hydrophilicity of the material, shows significantly better results for the plasma treated samples than for the ultrasonic treated ones, although not to the extent of satisfying the problem. Nevertheless, both pretreatments have the potential to fulfill the purpose of the study, but further research and testing is required to implement them in the industry.