No abstract

Polypropylene (PP)-knitted fabrics were finished with b-cyclodextrin (b-CD) and crosslinked with citric acid (CTR). The polyCTRb-CD polymer-coated fibers were wash resistant. We report that the rate of immobilized CD was controlled by temperature and curing time. The weight increase of the fabrics after modification with native b-CD and CTR reached 30 %wt. The treated PP supports were dyed using disperse, acid and reactive dyes. Standard tests of wash fastness (shade change and staining) were conducted and showed that all dyes were fixed, because of inclusion complexation with immobilized cavities on the one hand and sorbed hydrogen and ionic bonds that occurred between the polyCTR-b-CD coating and the tested dyestuffs on the other.

Polypropylene clay fibres loaded with different alkylammonium‐modified montmorillonite were prepared using a melt spinning technique and relationships between the structure and properties of the nanopolypropylene fibres are discussed. Experiments carried out using transmission electron microscopy showed that the chemical structure of the organic modifier and the interlayer spacing of the clay induced different dispersions of the clay, thus improving accessibility of the nano fibre. It is known that nanoclays are effective and efficient sorbents for dyes. Therefore, the dyeing behaviour of the nano polypropylene fibres with two distinct acid dyes and a disperse dye was studied and the build‐up of dyes, measured as colour yield, reported. The best results were obtained when the clay was well dispersed in nanopolypropylene fibres; that is, when maleated polypropylene was added as a compatibiliser and when disperse dye was used. Good wash fastness was then obtained.

Dyed polyamide fabrics tend to exhibit barriness, particularly when acid dyes of good wet fastness are used. The causes of this phenomenon have been investigated by studying the diffusion kinetics of the dyeing process. The conditions used in the pretreatment of the yarn have been considered, in particular the effect of mechanical and thermal conditions during thermal pretreatment. It has been demonstrated that barriness is dependent only on the kinetics of diffusion. If drawing is increased, the rate of dye diffusion is reduced, whereas an increase in the texturising temperature tends to increase it. The influence of dye diffusion decreases as the dyeing temperature rises. The traditional practice of dyers to attempt to reduce barriness by raising the dyebath temperature very slowly therefore makes matters worse. To reduce barring it would be preferable to introduce the dyestuff to the dyebath only once the dyeing temperature has been reached.