Coatings, polymeric

Itaconic acid is a specialty monomer that affords performance advantages to certain polymeric coatings (qv) (see Polyesters, unsaturated). Emulsion stabihty, flow properties of the formulated coating, and adhesion to substrates are improved by the acid. Acrylonitrile fibers with low levels of the acid comonomer exhibit improved dye receptivity which allows mote efficient dyeing to deeper shades (see Acrylonitrile polymers Fibers, acrylic) (10,11). Itaconic acid has also been incorporated in PAN precursors of carbon and graphite fibers (qv) and into ethylene ionomers (qv) (12). 

Specifications and Standards Test Methods. Hydroxyethylcellulose is included in the Hst of materials that are in compHance with requirements of the U.S. EDA for use in adhesives and in resinous and polymeric coatings employed on the food-contact surfaces of metal, paper, or paperboard articles, and other substrates intended for use in food packaging as specified in CER 21. HEC made dispersible by cross-linking with glyoxal is cleared only as an adhesive and as a component of paper and paperboard in contact with food. It has not been cleared as a direct food additive. 

Scotts technology (17) uses fluid-bed (Wurster column) technology to apply polymeric coatings to a number of fertilizer substrates including urea, potassium nitrate, potassium sulfate, and monoammonium phosphate (MAP). The coating material is appHed as a water-borne latex onto the fluidized substrate. As the substrate is fluidized with warm air (40—50°C), water is driven off and the latex coalesces into a continuous film around the fertilizer particle. The particular latex compositions used have selected glass-transition and blocking temperatures, which enable quick removal of the water before the soluble fertilizer core dissolves. This obviates the need to use precoats prior to the latex appHcation. 

A number of polymeric coatings, primarily polyimides, epoxies, and sHicones, are used as adhesives and ia other aspects of packagiag, as well as for final eacapsulatioa and protection of the iategrated circuit. 

Packham, D.E., The adhesion of polymers to metals the role of surface topography. In Mittal, K.L. (Ed.), Adhesion Aspects of Polymeric Coatings. Plenum, London, 1983, p. 19. 

A conductive polymer electrode has been designed specifically for the cathodic protection of steel reinforcing bars in concrete and is marketed under the trade name Ferex . The anode consists of a 16 AWG stranded copper conductor surrounded by a carbon-loaded polymeric coating similar to that used on the Anodeflex system ) to provide a nominal anode diameter of 8 mm The manufacturer claims that at the maximum recommended current density of 0 08 Am the anode life in concrete will be 32 years with a proportionately longer life at lower current densities. 

The polymeric coat formed on the substrate by radical and anion polymerization has been observed to be mosaic [313-315]. The polymer was there in the form of... 

The authors of [317] investigated compositions based on PS, PMMA and styrene-acrylonitrile copolymer grafted to various fillers and found that it was possible, in this manner, to obtain particles with a grafted polymeric coating of sufficiently homogeneous thickness. 

One can see that the relative elongation is lower in composites, but the modulus and, what is particularly important, durability of samples is higher. Obviously, the interaction between the polymeric coat and the matrix is particularly important in materials of this kind. This is illustrated by the data of Table 13 below. 

From the table it is seen that the enhanced energy interactions between the polymeric coat of the filler and the matrix does not always entail an upgraded complex of physico-mechanical characteristics of the composite. The authors of [210] have advanced an opinion that the enhanced filler-matrix interaction prevents formation of labile bonds between the two and hinders the relaxation processes at the interphases. 

Table 13. Effect of the chemical nature of the polymeric coat on properties of filled PVC (filler parts by wt. of chalk to 100 parts by wt. of PVC) [316]...

FIGURE 4-13 Structures of common polymeric coatings (a) Nafion, (b) polyvinyllferro-cene (c) polyvinylpyridine id) polypyrrole. 

Administration (FDA) approval of SIBS, used as the polymeric coating on the Taxus coronary stent, opened new avenues for polyisobutylene-based TPEs in biomedical engineering. 

T.K.Rehfeldt, Polymeric Coatings Degradation Properties. Report Number AFWAL-TR-84-4174, Air Force Wright Aeronautical Laboratory, (1984). 

TA Wheatley, CR Steuernagel. Latex emulsions for controlled drug delivery. In JW McGinity, ed. Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms,... 

Our research in this field is mainly carried out on a) synthesis and conversion of oligoorganoepoxystannanes b) free-radical copolymerization of organotin monomers with various vinyl monomers and c) cross-linking of organotin macromolecules and development of protective polymeric coatings with specific properties on their basis. 

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