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Effect of Industrial Washing and Laundering on the Colour Values of Knitted Denim

Mezarcıöz Serin

Fibres & Textiles in Eastern Europe

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2021

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Vol. 29, no. 6 (150)

65--71

EN

One of the most distinctive features of denim is that the warp yarn is dyed with indigo dye and the weft yarns are not dyed, i.e. white. Although warp yarns dyed with indigo dye are woven with different woven fabric weaves, classical denim fabrics weave are produced with 3/1 Z twill weave. The search for new products in denim has led businesses to produce denim-looking knitted fabrics. Denim-looking knitted garments are subjected to industrial washing at the production phase and repetitive household washing processes in daily life. Repeated washing and drying processes cause changes that can affect user satisfaction in terms of losing the colour of the fabric. Therefore, in this study, the colour values of knitted denim fabrics produced as an alternative to denim fabrics manufactured by traditional methods after various industrial (rinse, enzyme and stone washing) and home washes (5, 10, 20 times) were examined. For this, the CIELab colour system was taken as the basis for colour analysis on a spectrophotometer device. As a result of the washing processes performed on each fabric sample (household washing and rinse, enzyme, stone washing applications), it was observed that there were differences in colour values depending on the fibre type, loop yarn length, fabric construction and washing process.

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Krótka historia niektórych wzorów

Kroszczyński W.

Wiadomości Chemiczne

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2013

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[Z] 67, 7-8

733--749

EN

This article is an attempt to present how the classical detective work has been performed in order to determine chemical structures. In the past, discussion on these examples was the way of learning of the organic chemistry. Thermal degradation was the main method of analysis currently replaced with the spectroscopy. Perhaps the history of chemistry may help to understand mentalities of creators of new branches of science. On the other hand, it gives arguments for a cultivation of „impractical” sciences. The article describes the earliest attempts to present simple organic formulas undertaken by Couper and Kekulé. Examples of a transformation of aromatic compounds present how results of derivatization led to conclusions concerning structures. Experiments and logic line of thought was supported by a great intuition. More complicated molecules were investigated by degradation reactions. For example, A. Baeyer at the beginning of his investigations concerning indigo, subjected isatin (obtained from indigo by oxidation) to different reducing reagents. He obtained indoldiol, oxindole, indole etc. Then these relatively simple compounds were synthesized and served as by-products for indigo. Some methods of the industrial production of indigo were elaborated on the base of works of Baeyer [16–20]. Similarly, the structures of chrysin, brazilin and haematoxilin have been resolved mainly by their degradation. The final structures were confirmed by synthesis.

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Błękit Majów , jedno z najważniejszych osiągnięć Mezoameryki

Łukarska M., Zywert A., Kowalak S.

Wiadomości Chemiczne

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2012

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[Z] 66, 7-8

715-739

EN

The Maya Blue is a famous blue pigment developed by pre-Columbian civilizations of Mesoamerica and manufactured there for about thousand years. It was applied for body decoration, important for cruel religious rituals, as well as for artistic paintings, murals, or coloration of ceramics. Its production was abandoned in XVII century and the procedure forgotten. The chemical nature of this blue pigment remained a puzzle for a long time and only in nineteen sixties it was revealed [1, 2] that it is a composite consisting of inorganic matrix (palygorskite) that accommodates molecules of organic dye – indigo. The preparation procedure was rediscovered [3] and the products analogous to classical Maya Blue could be obtained by simple thermal insertion of indigo into palygorskite (and also into sepiolite). However, the nature of chemical interaction between dye and matrix that provides very high resistibility of resulting pigments remains still not satisfactorily explained. The hydrogen bonds or coordinative interaction with matrix cations are taken into an account. Zeolites and other molecular sieves can be efficiently applied as matrices for pigments similar to Maya Blue. The coloration and other properties of pigments can be considerably changed by initial modification of zeolites with various cations, what supports an important role of complexes formed by dye molecules and zeolite cations. On the other hand, the zeolite-like materials AlPO4 as well as to some extent mesoporous silica (with some contribution of micropores) lacking any cations are also efficient matrices for pigments analogous to Maya Blue. Not only indigo, but also indigo derivatives (leucoindigo, thioindigo, indigo carmine) could be embedded inside the molecular sieves. The thermal insertion as well as crystallization of zeolites from gels supplemented with respective dye can be used for pigment synthesis. It is interesting that role of matrix can be also played by representative of novel MOF family of the molecular sieves.

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Dyeing nylon with indigo in various pH regions

Baig G. A.

Autex Research Journal

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2010

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Vol. 10, no. 1

21--25

EN

Nylon (6.6) fabric was dyed with Indigo dye using an exhaust technique at different pH values. At different pH values different forms of indigo existed in solution, each one having a different substantivity for the fibre. The non-ionic form had the highest, whilst the Ionic ones had relatively less substantivity. The fibres could best be dyed in the acidic to slightly alkaline pH range. The Chemistry of the dyebath and fibre were considered, in order to explain the effect of pH on colour strength. Hydrogen bonding and ionic interactions seemed to be the main reason for the exhaustion of dye onto nylon fibre. Hydrogen bonding occurred between the hydroxyl groups and amide groups, while ionic interactions worked at low pH values between the ionized and end-amino groups of the dye and fibre respectively.