Water repellent/resistant

Figure 12.30 Potential uses of polyphosphazenes (a) A thin film of a poly(aminophosphazene) sueh materials are of interest for biomedical applications, (b) Fibres of poly[bis(trifluoroethoxy)phosphazene] these fibres are water-repellant, resistant to hydrolysis or strong sunlight, and do not burn, (c) Cotton cloth treated with a poly(fluoroalkoxyphosphazene) showing the water repellaney eonferred by the phosphazene. (d) Polyphosphazene elastomers are now being manufaetured for use in fuel lines, gaskets, O-rings, shock absorbers, and carburettor eomponents they are impervious to oils and fuels, do not bum, and remain flexible at very low temperatures. Photographs by eourtesy of H. R. Allcock (Pennsylvania State University) and the Firestone Tire and Rubber Company.

Cationic softener that exhausts to provide soft hand and reduced needle cutting on cotton and cotton blends. Nonrewetting, minimal effect on water repellency. Resists yellowing and scorching and gives excellent crockfastness. 

Water Repellency and Water Resistance. Water repeUency is defined as the abihty of a textile fiber, yam, or fabric to resist wetting, whereas water resistance is a general term appHed to a fabric s abiUty to resist wetting and penetration by water (2). A third term, waterproof, is appHed to those fabrics that do not allow any water penetration at all. Waterproof fabrics are generally coated with an impermeable surface layer that does not allow air permeabihty. Water-repellent finishes are hydrophobic compounds that are appHed to fabrics to inhibit water penetration while still allowing air permeabihty. 

In principle, emulsified sunscreen products are similar to emollient skin-care products in which some of the emollient Hpids are replaced by uv absorbers. The formulation of an effective sunscreen product generally requites combination of a uvB and a uvA absorber if an SPF above about 12 is desired. Two or more of the sunscreens Hsted in Table 13 normally constitute about one-half of the nonvolatiles found in sunscreen lotions. The other half consists of an em ollient (solvent) and emulsifying and bodying agents. If water-resistant quaUties are desired, polymeric film formers, for example, acrylates—octylacrylamide copolymers [9002-93-1] or water-repellent Hpids, for example, dimetbicone [9006-65-9] are included. 

MAI composed of PAIE for application to emulsifiers, drug carriers, and ion-exchange resins [60,61]. Poly(per-fluoropropyleneglycol)-b-poly(acrylic acid) was synthesized initiated with an MPI having fluoroalkyl group in the main chain [62]. It was soluble to water, ethanol, and THF, and showed water repellency, oil repellency, antifouling, and resistance to chemicals. 

Water repellant To impart water-resistant properties, particularly in greases Aliphatic amines, hydroxy fatty acids and some organic silicone polymers... 

Polysiloxanes as shrink-resist finishes have been developed from their traditional uses as softeners and water repellents as such their chemistry is discussed in section 10.10.3. This was a natural trend as many shrink-resist finishes tend to impart a harsh handle to wool. 

Mention has already been made of the effectiveness of corona or plasma treatment in increasing the influence of subsequent or concurrent polymer treatment. As examples of polymers used in this way, mention can be made of reactive cationic polysiloxane [294] and polymerisation on the fibre of tetrafluoroethylene or hexafluoropropylene [299]. Water repellency was also improved by the fluorinated polymers. Tetrafluoroethylene gave superior shrink resistance this polymer covered the scale edges of the wool, whereas this did not occur with poly(hexafluoropropylene). 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

Polyfluorinated chemicals now dominate in the fields of oil-repellent and water-repellent finishes. The earlier so-called conventional polyfluorinated products were of the type represented by poly(N-methylperfluoro-octanesulphonamidoethyl acrylate) (10.248) [499]. Such products presented a shield of closely packed fluoroalkyl groups at the fibre-air interface, thus giving low-energy surfaces with excellent oleophobicity. These showed excellent resistance to oil-based stains but were less satisfactory as soil-release agents during... 

These copolymers have been mentioned already in section 10.10.4 as versatile and highly effective stain-resist, oil- and water-repellent finishing agents. 

Designing effective water-repellent, water-resistant, or waterproof fabrics to provide protection in inclement weather or during certain outdoor activities requires an understanding of the chemical and physical properties of water. Whether you are sailing in wind-driven rain, hiking in a downpour, or sitting on a wet surface, chemistry can keep you dry ... 

Melamine resins also are used for the production of decorative laminates. The amino resins are able to modify textiles like cotton and rayon by imparting crease resistance, stiffness, shrinkage control, fire retardance and water repellency. They are also used to improve the wet strength, rub resistance and bursting strength of paper. 

They are hydrophobic and resistant to hydrolysis because of their hydrophobic nature. This change to a hydrophobic nature is positive for applications requiring water stability, resistance and repellency and is typical of most water soluble polymers (such as poly(acrylic acid), polyethyleneimine and poly(vinyl alcohol)... 

Hydrophilic Refers to a substance or chemical that has a high affinity for moisture or water. Hydrophobic Refers to a substance or chemical that is poorly soluble in water water repellant. A hydrophobic agent is a chemical having the ability to resist wetting by water. It can be used in the treatment of synthetic sorbents to decrease the amount of water absorbed, hence increasing the volume of oil they can absorb before becoming saturated. 

Impart water repellency and stain resistance to masonry sur-... 

Flake aluminum pigments with varying platelet thicknesses and shapes are used for corrosion protection [5.175]. For standard specifications, see Table 1 ( Aluminum pastes and pigments ). They are coated with a water-repellent, fatty film and are therefore particularly suitable for conventional solventbome coating systems. They have outstandingly good weather resistance [5.175]—[5.177]. 

---