Fibres hydrophobic properties

The use of cold-plasma can be applied to modify the fibres surface properties in two opposite directions, namely an increase in the hydrophilic character when the treatment is carried out in Argon or air [18, 76] and, on the contrary, the formation of a super-hydrophobic surface when fluorinated gases are used [18, 77-80]. A very recent publication illustrates clearly the latter approach [80]. In this study, paper sheets were plasma irradiated in the presence of CF4 and the surface modification characterized by XPS, ATR-FTIR as a function of the power parameters and the CF4 pressure. Interestingly, no significant difference was observed in the extent of modification to either side of the sheet. Figure 18.2 shows a typical XPS spectrum of one of these modified surfaces. 

Abstract Enzymatic polymer functionalisation has entered its most fascinating period with development in this field largely at the basic research level and pilot scale applications. Development of enzymatic processes for the development of lignocellulose-based functional polymers has not been spared, ranging from textile fibres with novel properties (antimicrobials properties, hydrophobic properties, attractive shed colours, etc.) to fibreboards. Enzymatic processes are also being actively pursued aimed at developing functional polymers from lignin (a major by product of the pulp and process). 

Hair is complex multicomponent fibre with both hydrophilic and hydrophobic properties. It consists of 65-95% by weight of protein and up to 32% water, lipids, pigments and trace elements. The proteins are made of structured hard a-keratin embedded in an amorphous, proteinaceous matrix. Human hair is a modified epidermal structure, originating from small sacs called follicles that are located at the... 

Cellulosic fibres having hydrophobic properties are also attractive to filter media. 

Schachtner B, Smith R. WO2013067555, Cellulosic fibres with hydrophobic properties. 2013. 

Modem electrodes tend to use carbon-supported catalysts, mixed with PTFE, which are then rolled out onto a material such as nickel mesh. The PTFE acts as a binder, and its hydrophobic properties also stop the electrode from flooding and provide for controlled permeation of the electrode by the liquid electrolyte. A thin layer of PTFE is put over the surface of the electrode to further control the porosity and to prevent the electrolyte passing through the electrode, without the need to pressurise the reactant gases, as has to be done with the porous metal electrodes. Carbon fibre is sometimes added to the mix to increase strength, conductivity, and roughness. Such an electrode is shown in Figure 5.8. 

Regardless of their fibre composition and the type of the manufactured item, cloths for waterproof clothing should have a high and stable hydrophobicity, at the same time preserving their hygienic properties, wear resistance, form stability and attractive appearance. 

The fact that the majority of in vivo processes occur on the surface of or within the membrane and that electrical phenomena are very important in membranes such as those found in the chloroplast, muscle fibres, nerve fibres, mitochondria, etc., has recently led to intensive study of the electrical properties of bilayer lipid membranes (BLM) in an attempt to reproduce a model of the cell membrane. Membranes of 5-10 nm thickness have been studied, the membranes consisting of two parallel sheets of lipids with a hydrophobic environment in the interior of the membrane and the hydrophilic groups directed to the exterior aqueous medium. 

Figure 3.2 shows typical cationic softener structures, for example, A,A-distearyl-A,iV-dimethyl ammonium chloride (DSDMAC). Cationic softeners have the best sofmess and are reasonably durable to laundering. They can be applied by exhaustion to all fibres from a high liquor to goods ratio bath and they provide a hydrophobic surface and poor rewetting properties, because their hydrophobic groups are oriented away from the fibre surface They are usually not compatible with anionic products (precipitation of insoluble adducts). 

Why then, should we be concerned with the nature of the surface complexes This result from the fact that many of the properties of carbons are known to depend on the particular surface complexes that are present. Thus, for example, pure carbon is hydrophobic, a property that decreases if oxygen is present. As a result, low temperature oxidation of carbon blacks is often used to improve hydrophilic properties. Again, Studebaker and Snow have shown that the contact angle of liquids in contrast with carbons was a function of oxygen (and hydrogen contents and a similar relationship has been found to hold for carbon fibres. ... 

Historically the first commercially successful synthetic fibre was Nylon 66. At the time when it appeared on the market its dyeing presented many difficulties. The fibre is hydrophobic and, therefore, not very attractive to water-soluble dyes. In the early stages of manufacture the polymer was liable to vary from batch to batch, both in physical properties and with regard to the number of amino end groups. This caused variations in affinity for dyes producing barry effects, unless great care was taken to keep each batch separate. 

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