Hydrophile Polysiloxane als waschbeständige Textilhilfsmittel
This work focuses on the kinetics of the application and washing process of two different functionalized silicones on cotton fabric. The first, a polyquaternary polysiloxane - blockcopolymer, interacts by hydrogen bonding to the hydroxyl-groups of the cotton fibre. The second, a reactive functionalized polyquaternary polysiloxane-block-copolymer consists of uretdione functions, which can react with either the hydroxyl groups of the cellulose or with OH-groups of the silicone to form a silicone network. In this work the kinetic aspects of the finishing and washing process are decribed. The first examinations to analyse the application process were done using a fluorescent ammonium functionalized silicone softener. This modification allows measurements of the silicone concentration in the bath during the application by photometric detection. The fibre cross section could be analysed by fluorescence microscopy during the application process. The bath analysis shows that the application process follows a sorption isotherm described by Langmuir. The examinations by fluorescence microscopy show a change in the cross section of the fibre towards an oval shape after treatment and a diffusion of the silicone polymer into the lumen. The examination of the fiber surface during the application process with a non fluorescent modified silicon polymer was accomplished by XPS. The changes in the concentration of silicone in the bath were measured by photometric detection after reaction of the ammonium groups of the silicone with bromophenol blue. The kinetics can be described by the square-root-t-relation. The resulting rate constants do not differ significantly for different bath temperatures. The examinations by XPS and IR-spectroscopy of the washing process showed a diffusion of the silicone molecules from the core to the surface of the fibre, where they are removed by the surfactants of the washing bath. XPS results show that after one washing cycle the silicone concentration on the surface stays almost constant. The IR-spectroscopic examinations indicate a continuous decrease of silicone in the fibre. In parallel to the spectroscopic analysis of the fiber surface the changes in the silicone concentration in the bath were analysed by photometric detection. The examinations showed a square-root-t-relation for the washing process. In another part the influence of the silicone treatment to the evenness of the coloration of a yellow dyed cotton skirt was examined by datacolor measurement and CIELAB interpretation. Further examinations showed that an overdose of silicone during the finishing causes discoloration which is an undesirable effect. In this part, the application process of the reactive functionalized polyquaternary polysiloxane-block-copolymer silicone was examined by fluorescent microscopy. In a similar manner to the non-reactive silicones, the reactive silicones diffuse into the fibre, but in this case but no change in fiber cross section could be observed. The amount of applied silicone on the fiber was much lower compared with the fibers treated with the non-reactive silicone. The kinetics of the application process follows a square root-t- relation. The rate constants are very similar to those for the non-reactive silicone polymers. It is likely that the silicones build a charged layer in the pores of the cotton fibre, which repels any further silicone molecules diffusing into the pores. That implies that no further molecules can diffuse into the pores, which is proven by a very low swelling of the fibre and a very low rate of exhaustion. The improved washing resistance in comparison to the non-reactive silicones is due to the chemical bonding to the fibre, which is much stronger than for the non-reactive silicone.
info:eu-repo/classification/ddc/540, Silicone, Reaktionskinetik, Baumwollfaser, Röntgen-Photoelektronenspektroskopie, Chemie, Ficksche Gesetze, CIELAB System, Polysiloxane, FT-IR Spektroskopie, Waschkinetik, Aufziehkinetik, Fick Law, FT-IR Spectroscopy, washing kinetics, application kinetics
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