Epoxy-based polymer coatings

TABLE 14.1 Surface modulation of SRGs produced at 488 nm with an intensity of 50 mW/cm under various poiaiization combinations on a 0.7 p,m thick spin-coated film of an epoxy-based polymer (CH-iA-CA). 

Among the various applications suggested for hyperbranched polymers are surface modification, additives, tougheners for epoxy-based composites, coatings, and medicines. 

Among the various applications suggested for hyperbranched polymers are surface modification, additives, tougheners for epoxy-based composites, coatings, and medicines. It has been demonstrated that hydrophobic, fluorinated, hyperbranched poly(acrylic acid) films can passivate and block electrochemical reactions on metal surfaces thus preventing surface corrosion (Bruening, 1997). The lack of mechanical strength makes hyperbranched polymers more suitable as ad-... 

Worsley and coworkers utilized an SVET to investigate the corrosion at cut edges of coil-coated steel [143]. Samples were hot-dip galvanized steel, chromate treated and coated on both sides by a 5-pm epoxy-based polymer. A 140-p.m PVC laminate coating was applied to one or both sides of the sheet to produce asymmetrically and symmetrically coated samples. Measurements were done in 0.86 M NaCl solution. Interestingly, the measurements of Kne... 

Coatings such as a zinc silicate primer covered with a layer of an epoxy-based polymer are routinely applied to steel structures to protect them against corrosion. However, cracks or flaws in the coating expose Fe which then undergoes oxidation in an anodic process. To prevent this, a second protection system is put in place cathodic protection. By placing a block of a more electropositive metal on the surface, this second metal is preferentially oxidized. This is the same principle as the use of zinc in galvanized steel (see Section 6.7). From Table 8.1, you can see why Zn, A1 and Mg (or alloys of these metals) are typically chosen as sacrificial anodes. The most electropositive metals (Li, Na, K and Ca) are unsuitable because they react with cold water. The relevant half-equations (at pH 7) are now ... 

Recent additions to the search of lignin-based polymers include the use of lignin oligomers and vegetable oils to elaborate paper hydrophobic coatings [65] and the preparation of epoxy networks derived from lignosulfonate and glycerol [66]. 

Thicker epoxy-based coatings, highly flexibllized with amine-reactive nitrile liquid polymer, have been described by Mendelsohn (50) in which the flexibilizing hardener is comprised of an admixture of ATBN, fatty polyamide and boron trifluoride/amine complex. This coating ages well at 100°C and has excellent toughness/ flex with good abrasion and vibration absorption properties. 

Recent information suggests that such coatings operate by increasing the electrical resistance between the steel and the concrete both epoxy and polymer-cement-based materials seem to have this effect, reducing local corrosion current exchange [9]. 

They are synthesized from polymers of primarily polymethacrylate, acrylate esters, and polyethyl acrylate (Fig. 13.2). Acrylate resins are very stable in oxygen and UV light and are resistant to weathering and frequently used in the automobile industry as topcoats. Water-based acrylics are used as household paints. For ultraviolet resistance and improved weathering, acrylic resins are used as modifiers for epoxy and alkyd coatings. 

Electrostatic layer-by-layer (LBL) self-assembly techniques based on oppositely charged poipelectrolytes can be useful to create stable noncentrosymmetric order in thin films. Using this interesting technique, thermodynamically stable noncentrosymmetric multilayer films can be prepared without any need for poling. Tripathy et al. reported the fabrication stable multilayer films of epoxy-based side chain azo polymers for second-order nonlinear optics.The second-order NLO coefficients of the five-bilayer LBL films of these polymers were found to be comparable to those of spin-coated poled films. A schematic view of the procedure to fabricate polyelectrolyte-based LBL films is shown in Fig. 7. 

Uses Phenolic, adhesion promoter, chem. resist, aid for drum and pail coatings, latex and phenoxy polymers crosslinking agent for water-based polymers intended for low VQC applies. food pkg. adhesives, coatings, paper, closures with sealing gaskets for food containers Features Thermosetting compat. with various waterborne acrylic, epoxy, and phenoxy resins... 

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