Composite coating applications

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

Diffusion Coating-application of a metallic coating. The chemical composition of the metal is modified by diffusing the coating into the substrate at the metal s melting temperature. 

The effect of the initiation and termination processes on compositional heterogeneity can be seen in data presented in Figure 7.3 and Figure 7.4. The data come from a computer simulation of the synthesis of a hydroxy functional oligomer prepared from S, BA, and HEA with a thiol chain transfer agent. The recipe is similar to those used in some coatings applications. 

Coating Applications. The compositions and the performance coatings are described in Table I. The coatings are prepared by the same procedure as described in the oligomer preparation. 

The carbides and nitrides of vanadium and titanium crystallize in the same face centered cubic (fee) system, and because of the closeness of their cell parameters (Table 15.1) form solid solutions. These ceramic materials exhibit interesting mechanical, thermal, chemical and conductive properties.1,2 Their high melting point, hardness and wide range of composition have therefore attracted considerable attention in the last decade. Moreover, their good abrasion resistance and low friction also make these ceramics attractive for protective coating applications.3-5 Chemical vapor deposition (CVD) is a commonly used technique for the production of such materials. In the conventional thermally activated process, a mixture of gases is used.6-9 In the case of TiC, TiN, VC and VN, this mixture is... 

To achieve the main process requirements (ability to be applied by different methods by hand, spray, electropaint), and to provide the necessary decorative, physical, and mechanical properties, organic solvents are used in concentrations up to of about 50% to modify the viscosity and other rheological characteristics of the some polymer compositions. During the application and formation of the coating, the solvents evaporate into the atmosphere as pollutants. This serious disadvantage of formulations based on the use of solvents as "intermediate" carriers has provided the incentive to develop polymer compositions and application technologies which yield the required rheological characteristics either without solvents, or at least with low concentrations of them. 

The properties of a typical Chevron sulfur composite are shown in Table I. One desirable feature is the low melt viscosity in the 250°-300°F range. This provides considerable latitude in the choice of application methods. Spray has proven to be effective for many uses. Brush, roller, and dipping have also been used for some coating applications. Most composites can be put into service immediately after application because they attain most of their strength and durability shortly after they solidify from the melt. 

Acrylic Macromonomers. Acrylic-methacrylic macromonomers prepared by catalytic chain transfer using cobalt(II) chelates afford polymer chains, each with an olefinic endgroup (18, 24). Such macromonomers can be polymerized or copolymerized to produce graft polymers that are useful in coatings, fibers, films, and composite materials applications (24). Moreover, one is able to synthesize macromonomers containing several alkylmethacrylates, alkylacrylates, and styrene (IS). 

This can be viewed either starting from the top left (technology push) or the bottom (market pull). Starting with synthesis, why alter polymer composition Control of polymer chemistry and synthesis leads to a defined polymer architecture, i.e. the chemical and physical composition of a polymer chain. This architecture influences the basic properties of bundles of polymer chains, which then correlate with applied properties. The polymerisation process may affect the polymer architecture produced and the coating process will influence both the basic and applied properties. Basic properties are independent of the application whereas applied properties may be application specific. For surface coatings applications, the overall performance will be influenced by other raw materials in the formulation, depending on the nature of the individual components and the interaction between them. Improvement in specific... 

Applications of supercritical fluids for coatings and impregnation of porous and fibrous substrates (e.g., polymer fibers, wood, composite materials) with various chemicals are discussed in a number of articles (50-52). Mandel and Wang (53) reported the use of a solution of polymers diluted with SCCO2 for powder-coating applications. They reported that Ferro Corporation has developed the so-called VAMP process used in the production of powder coatings, new polymers and polymer additives, and various biomaterials, with good potential for productions of pharmaceuticals. 

Evaluation test of C/C composites coated with SiC/C FGM, under simulated condition for aerospace application... 

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

---