Lyocell fibers have extraordinary textile properties, but they show a distinct tendency to fibrillate in the wet state. Treatments with crosslinking compounds used for textile finishing could be a practical means of controlling this problem. Some polyfunctional reactive dyestuffs also greatly increase wet abrasion resistance. Fiber tenacity decreases slightly compared to reactive compounds used for easy care finishing.Alternative methods for the dissolution of cellulose have been studied for many years. Cellulose-N-methylmorpholine-N-oxide-water has become a key system and is already used for industrial production of cellulosic fibers. Lyocell fibers have extraordinary dry, wet, and loop strength and low shrinkage compared to viscose fibers, but they show a distinct tendency to fibrillate under mechanical stress in the wet state. Fibrils split lengthwise along the fiber axis and show up, macroscopically, as a fibrous surface with local greying. While this property has some applications, for example, for textiles with particular surface structure, it prevents their wider use in the industry. From fundamental research on the structure of Lyocell fibers, workers concluded that the spinning process causes the formation of a large fraction of highly oriented crystalline regions. The lateral links between the crystallites are weaker than those in viscose or in modal fibers [3, 4, 91. Previous work [6] revealed a good correlation between the results of our wet abrasion test [7] of different fibers and the cluster fraction defined in reference 5.The ekmentary fibrils of solvent spun cellulosic fibers are less aggregated than the fibrils generated by a viscose process, and they also show the lowest wet abrasion numbers.
Summary: One strategy to solve the problem of unwanted PET oligomer deposits in textile production is their enzymatic cleavage. In this work a selection of different enzymes (esterases, lipases) were tested for this purpose. The capacity to hydrolyse PET oligomers of some of the tested enzymes has been previously described in the literature. In order to imitate practical conditions both dry and precipitated PET oligomers were used. The decrease in the amount of cyclic trimer, the main component of the PET oligomers, was monitored by HPLC. After treatment with the lipase from Triticum aestivum a decrease of 80 wt.‐% was found. However, the effect of this lipase seems to have less to do with catalysing hydrolytic cleavages of ester groups than with the absorption of the oligomer on the enzyme protein.Cyclic PET trimer (cyclo‐tris[ethyleneglycolterephthalate]).magnified imageCyclic PET trimer (cyclo‐tris[ethyleneglycolterephthalate]).
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