Barbora Široká

Characterization of cellulosic fibers and fabrics by sorption/desorption

Three cellulosic substrates: lyocell (CLY), viscose (CV), and modal (CMD) in the form of fibers and fabrics were subjected to wet/dry or wash/dry treatments. The accessibility of untreated and treated substrates to water and iodine was investigated using dynamic water-vapor sorption, moisture retention, and iodine sorption methods, to study the influence of treatments on sorption-desorption hysteresis, fraction of moisture sorbed as a monomolecular layer, water retention, and iodine sorption. It was found that the sorption properties of untreated and treated substrates differed with sorbate type as well as substrate type and form.

Copper inclusion in cellulose using sodium D-gluconate complexes.

Copper containing cellulose material is of growing interest, e.g. offering alternative in the field of antimicrobials. Solutions of copper d-gluconate complexes (Cu(2+)-DGL) were used to introduce copper ions into a swollen cellulosic matrix. A ligand exchange mechanism forms the chemical basis of the sorption process. Copper sorption in cellulose was studied in the range between pH 6 and 13. An estimate for the complex stabilities of the Cu-cellulose system could be derived from the calculated species distribution of the different Cu(2+)-DGL complexes present. Spectrophotometry and cyclic voltammetry of Cu(2+)-DGL complex solution were used to confirm the presence of different species participating in the ligand exchange reaction. The pH dependent uptake of Cu(2+) ions in the cellulose matrix can be explained on the basis of the relative stabilities of Cu(2+)-DGL complex vs. Cu(2+)-cellulose complexes. In comparison to pH 10, higher copper content was observed at pH 6 and 13. Copper content was limited by carboxyl content of cellulosic materials, thus in analogy to the structure of Cu(2+)-DGL complexes participation of the carboxyl group as complex forming site is proposed. At high Cu(2+)-concentration and longer time of immersion in the copper complex solutions formation of solid deposits was observed on the surface of the treated fibres.

Ion-interactions as driving force in polysaccharide assembly

The structure of cellulose is characterised by extensive non-covalent interactions. Recent discussions suggest that hydrophobic interactions between polymer chains also play a significant role in governing cellulose solubility. Surprisingly in almost all cellulose shaping processes, chemical systems or solvents are applied, which base on melts or solutions of charged molecules. Ionic interactions play a significant role in the shaping and modification of cellulose based materials. Dependent on the systems used different principles govern the processes and define the results, e.g. formation of associates with alkali hydroxides, ion-exchange reactions to selectively bind multivalent ions at carboxylic groups, adsorption of dissolved polymers through surface charge neutralisation or metal complex formation, where cellulose takes the role of a polymer ligand system. Presence of charged compounds takes a significant role in cellulose swelling and dissolution, but also directs reassembly of polysaccharide material to solid three-dimensional structures.

Application of ATR-FT-IR Single-Fiber Analysis for the Identification of a Foreign Polymer in Textile Matrix

Identification of foreign fibers in yarn or fabric is of great interest to textile manufacturers. The goal of this work is to demonstrate the feasibility of single-fiber ATR-FT-IR spectroscopy to achieve prompt identification of foreign polymer brought into fibers during spinning. Testing of several fibers with different fineness proved the methods suitability for fast identification of foreign polymer. Owing to the nondestructive character of the method, the identification of foreign polymer was confirmed by other methods applied to the same samples, namely, melting temperature measurement and optical microscopy. The additional method for detection of foreign fiber by using image analysis was also applied.

Alkali Treatments of Woven Lyocell Fabrics

We are surrounded by textile fabrics every second of our daily life. Being produced in enormous amounts, these products were considered simple mechanical constructions for a long time. During the last few decades aspects of functional products and smart textiles directed more scientific attention towards a more profound understanding of the relations between fabric structure and performance properties.

Caregiver’s vision of bedding textiles for elderly

Senior citizens have specific needs for bedding, clothing, hygiene and medical textiles that are an essential part of their daily life. The “Textiles for Ageing Society (TAGS)” project deals with these specific demands. Caregivers from 6 European countries were asked by means of a semi-structured interview, how bedding textiles can contribute to daily care work. We found that better design could support care work substantially. As examples, in the short term, better design of colour and style should avoid a hospital like appearance, and better control of bed climate will improve a resident’s sleep quality. Long term developments are prevented by a number of barriers. Introduction of new bedding concepts is retarded by the fragmented situation between the elderly, care givers, purchasers, manufacturers, researchers, care organisations and politics which needs to be overcome. Caregivers as experts must be heard and their needs must be transformed into more appropriate, cost effective designs of bedding textiles, which can support to the quality of residents in care homes substantially. More intelligent textiles substantially could contribute to support care workers, however their potential has not been exploited yet.

Polysaccharide Fibres in Textiles

Besides naturally grown cellulose fibres like cotton, hemp or flax, interest in textile fibres made up from regenerated cellulose is growing. By sure the use of a polymer material, which is provided by nature in huge amounts, favours its use as more sustainable material compared to oil-based products. However, a much stronger argument is the high variability of the properties that can be achieved, which allows design an extremely wide range of products.