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It was shown that in treating PET fibre materials with a solution of ultradisperse, low-molecular-weight polytetrafluoroethylene in supercritical carbon dioxide, an ultrathin layer of fluoropolymer that gives the fabric a high degree of water repellency is formed on the surface.Due to the high demand for water-repellent textile materials for industrial and household applications, the problem of manufacturing stable and strong water-repellent coatings on widely used poly(ethylene terephthalate) (PET) materials is pressing. Despite the hydrophoby of PET fibres, the textile materials made from them cannot retain drops of liquid on their surface. Liquid instantaneously passes through the fabric due to forces of capillary suction of the complex fibres. PET materials have surface energy which is excess for the liquids in contact with them during use.To give PET textile materials stable unwettability, their surface energy must be significantly reduced. To do this, it is necessary to apply a substance whose hydrophobic sections are oriented to the outside area on each fibre without overlapping the micropores of the textile. A new outer surface with low surface energy is formed in this way.Water repellents are used in practice to manufacture fabrics with water-repellent properties, and effective textile auxiliaries based on fluorinated hydrocarbons are very popular [1]. However, the effect obtained with these preparations is not sufficiently stable, especially on synthetic fabrics. This is because the preparations based on fluorinated hydrocarbons are insoluble in water and are thus applied from emulsions and dispersions. They form weakly bound, thick, condensed layers on the surface of synthetic fibres which are easily washed off in laundering and dry cleaning and are rubbed off as the fabric is used.Attempts have been made to improve the composition of the product to eliminate this drawback. In particular, one of the world leaders in developing and manufacturing products for the textile chemistry, the Swiss firm Clariant, is offering a new series of fluorine-containing products for hydro-and oleophobic finishing -the Nuva group of products [2]. These products ensure that fabrics of different composition are given excellent oil-and water-repellent properties. However, the products are used in high concentrations (for synthetics, 10-30 g/liter) [2] and are very expensive. In addition, the inadequate resistance of the effect attained to the effects of use persist, since the water repellents are also applied from emulsions or dispersions.This drawback can be eliminated by applying a water-repellent substance from natural solution. In this case, it is no longer necessary to use specially synthesized complex products based on polymer compositions of fluorinated hydrocarbons containing emulsifiers. An additional advantage of stopping use of complex water-repellent products containing cationactive emulsifiers is reducing the tendency of the water-repellent textile material toward dry soiling. An industrially manufactured fluori...

No abstract

It was shown that an ultrathin continuous fl uoropolymer fi lm that replicates the microrelief of the fi bres forming the fabric is formed on the surface of polyester fabric when it is treated with a solution of a low-molecular-weight fraction of polytetrafl uoroethylene in supercritical carbon dioxide. The protective coating formed is ultrahydrophobic and has extremely low water absorption. An additional increase in the degree of hydrophoby of polyester fabric can be attained by using the chemical method of preliminary modifi cation of the fabric which gives the surface of the polyester fi bres additional roughness.There is an increasing demand for water-resistant textiles on the textile materials market, so that the problem of obtaining household and industrial fabrics with high hydrophoby is pressing. Water-repellent fi nishing of textile materials is to give them the capacity of not being wet with water while retaining air and vapor permeability. The contact angle of wetting  -the angle between the tangent to the surface of a drop of liquid at the point of contact of three phases (solid, liquid, and gas) and the surface of a solid, measured inside the liquid phase [2], is the basic index of the hydrophoby of a material, and it should be greater than 90°. Investigators have focused attention on highly hydrophobic -ultra-( > 120°) and superhydrophobic ( > 150°) -materials [3]. The ability of a material with a fl at, smooth, nonporous surface to be wet by liquids is described by Young's equation [2]:where  sg is the surface tension on the solid-gas interface;  sl is the surface tension on the solid-liquid interface;  lg is the surface tension on the liquid-gas interface. A real textile material has a biporous (micro-and macropores) system with a different degree of development. When such materials react with a liquid, it is necessary to take into account the appearance of forces of capillary suction. In this case, the Laplace equation [2], which correlates the capillary pressure (P c ) with the surface tension of the liquid ( lg ) and the average capillary radius (r c ) applies:It follows from Eq. (2) that the capillary pressure will approach zero with no wetting of the capillary walls. It is necessary to consider that Eq. (1) only holds for smooth surfaces, while textile materials are rough. One of two types of wetting takes place on rough surfaces [3]: homogeneous, where the liquid totally fi lls the cavities on the entire surface of the solid, and heterogeneous, where the liquid is in contact with the surface which has cavities totally or partially fi lled with air. For this reason, for describing the effect of roughness on the contact angle of wetting, either Wenzel's equation (3) (for

In this paper, we show that functionalization of fibrous materials through coating formation is hindered by the need to preserve the capillary-porous system of the fabric and its drapability. Additionally, such coatings must be resistant to abrasion and washing. We consider ways of solving these problems by analysing the formation of a stable coating based on photoactive titanium dioxide on a polyester fibre material as an example. The purpose of such coatings is to destroy coloured organic contaminants when the fabric is exposed to sunlight. We show that a polyester fabric with a titanium dioxide coating can become highly photochemically active and capable of inhibiting the vital activity of gram-negative bacteria and remaining soft and breathable at the same time. We also determined that depositing a titanium dioxide coating does not reduce the polyester fabric tensile strength. Polyester fabrics with photoactive properties can be widely used as decorative and trimming materials—for housing decoration, production of curtains and other decorative interior design elements.