Wettability improvement

Wettability Improvement of Metallic Surfaces by Active and Passive Plasma Cleaning... 

We have developed the high performance of flame-retardant additives, which consists of phosphazene skeleton. Partially flnorinated cyclophosphazene shows excellent ability not only for flame-retardance but for cell performance, dendrite suppressor, and wettability improvement as well. The additives show no or little stimulus for skin, low toxicity, and no carcinogenicity. 

Research on additives involves numerous other additives separate from those mentioned above, for example, additives for wettability improvement [36] and corrosion inhibition [37] as well as new lithium salts which can be used as substitutes for LiPFg and LiBF4 [38], Relevant case studies are also reported. 

In this section, we present additives for wettability improvement, additives for corrosion inhibition, and lithium salts. 

A wheat protein hydrolysate with a molecular weight range of 5000-10,000 Daltons used in 1 % concentration in a shampoo formulation has been found to lower the average coefficient of friction of the hair, giving lubricity and enhanced wettability, improve hair smoothness, as evaluated by atomic force microscopy visualization, and increase foamabil-ity of the preparation more effectively than other vegetable and animal hydrolysates (126). 

When incorporated—by extrusion—into a PO matrix, the hydrophilic modifiers do not offer any appreciable wettability, but when they are used in conjunction with polar substrates, PO wettability improves significantly. These polymers provide improved dyeability with a broad range of disperse dyes. The final shade of the dyed produet is brighter, deeper, and sharper than prior to PP fibers, with improved washfastness and eroekfastness. 

Most printing ink emulsions are resin supported . Printing ink emulsion polymers contain a support resin to reduce MFFT (minimum film forming temperature), and insure film coalescence. A support resin also decreases the need for surfactants. A support resin provides ink re-wettability, improves compatibility with pigment dispersions, and improves ink transfer and printability. Support resins are typically styrene acrylic polymers with acid functionality that are amine neutrahzed. 

This paper presents photografting as a surface modification method to provide permanent wettability improvement to deep-groove polypropylene (PP) fibers. We also describe approaches to evaluate the wettability of these fibers and the wicking performance of fiber bundles when polyacrylamide (PAAm) was grafted onto the fibers. In this study, the concentration of the monomer and the UV-exposure time were altered to examine the effects of those variables on fiber hydrophilicity. Results showed lower water contact angle and improved wicking capacity upon modification with PAAm. 

Lithium fluoride is an essential component of the fluorine cell electrolyte 1% LiF in the KF 2HF electrolyte improves the wettability of the carbon anodes and lowers the tendency of the cells to depolarize (18). Thermoluminescent radiation dosimeters used in personnel and environmental monitoring and in radiation therapy contain lithium fluoride powder, extmded ribbons, or rods (19). 

Wettable powders are prepared by blending the toxicant in high concentration, usually from 15 ndash 95%, with a dust carrier such as attapulgite which wets and suspends properly in water. One to two percent of a surface-active agent usually is added to improve the wetting and suspensibiUty of the powder. Sprays of wettable powders are used widely in agriculture because of their relative safety to plants. 

Tackifying resins enhance the adhesion of non-polar elastomers by improving wettability, increasing polarity and altering the viscoelastic properties. Dahlquist [31 ] established the first evidence of the modification of the viscoelastic properties of an elastomer by adding resins, and demonstrated that the performance of pressure-sensitive adhesives was related to the creep compliance. Later, Aubrey and Sherriff [32] demonstrated that a relationship between peel strength and viscoelasticity in natural rubber-low molecular resins blends existed. Class and Chu [33] used the dynamic mechanical measurements to demonstrate that compatible resins with an elastomer produced a decrease in the elastic modulus at room temperature and an increase in the tan <5 peak (which indicated the glass transition temperature of the resin-elastomer blend). Resins which are incompatible with an elastomer caused an increase in the elastic modulus at room temperature and showed two distinct maxima in the tan <5 curve. 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

Thermal aging is another simple pretreatment process that can effectively improve adhesion properties of polymers. Polyethylene becomes wettable and bondable by exposing to a blast of hot ( 500°C) air [47]. Melt-extruded polyethylene gets oxidized and as a result, carbonyl, carboxyl, and hydroperoxide groups are introduced onto the surface [48]. 

Wettability—coupling agents improve the wetting between polymer and substrate (critical surface tension factor). 

Cleanness of the base, i.e. freedom from grease, which improves the wettability of the metal surface, and the removal of oxides, dust or loose paint, etc. already described. The closer the surfaces of paint film and metal, the more secondary valencies originating in the polar constituents of the medium are brought into play. 

For converting rust to clinging layers as a basis for coatings of paint and varnish, the addition of alkyl phosphates to phosphoric acid is suggested to improve its wettability and penetration [260]. 

The application of surface treatments to mbbers should produce improved wettability, creation of polar moieties able to react with the adhesive, cracks and heterogeneities should be formed to facilitate the mechanical interlocking with the adhesive, and an efficient removal of antiadherend moieties (zinc stearate, paraffin wax, and processing oils) have to be reached. Several types of surface preparation involving solvent wiping, mechanical and chemical treatments, and primers have been proposed to improve the adhesion of vulcanized SBR soles. However, chlorination with solutions of trichloroisocyanuric acid (TCI) in different solvents is by far the most common surface preparation for mbbers. 

The treatment with sulfuric acid produces a noticeable decrease in contact angle (i.e., improved wettability) due to the removal of zinc stearate and the formation of polar moieties on the mbber, mainly the creation of highly conjugated C=C bonds and the sulfonation of the butadiene units (Figure 27.1), i.e., the hydrogen of C—H bond is removed and replaced by a SO3 molecule, which is then hydrogenated to form a sulfonic acid at the site of attachment. The treatment is not restricted to the surface but also produces a bulk modification of the mbber. 

Thermodynamical adhesion. Treatment with TCI solution improves the wettability on SBR, due to the creation of surface chemistry and roughness. 

Corona discharge has been successfully used to improve the adhesion of TRs to polyurethane adhesive. The treatment with corona discharge improves the wettability of TR due to the surface... 

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