Epoxy-Polyurethanes

PVF resins are generally compatible with phthalate, phosphate, adipate, and diben2oate plastici2ers, and with phenoHc, melamine—formaldehyde, urea—formaldehyde, unsaturated polyester, epoxy, polyurethane, and cellulose acetate butylate resins. They are incompatible with polyamide, ethyl cellulose, and poly(vinyl chloride) resins (141). 

Property Epoxy Polyurethane Polyester Hybrid AcryHc... 

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Gluing is possible with adhesives based on epoxies, polyurethanes, silicones, cyanoacrylates and hot-melts. All precautions must be taken concerning health and safety according to local laws and regulations. 

Reversion is usually much faster in flexible materials because water permeates them more easily. Hydrolysis has been seen in certain epoxy, polyurethane, and cyanoacrylate adhesives. The reversion rate also depends on the type and amount of catalyst used in the formulations and the degree of crosslinking. Best hydrolytic properties are obtained when the proper stoichiometric ratio of base material to catalyst is used. 

Chlorinated Polyether. This thermoplastic resists most solvents and is attacked only by nitric acid and fuming sulfuric acids. Thus, it is not capable of being solvent-cemented. Chlorinated polyether parts can be bonded with epoxy, polyurethane, and polysulfide-epoxy adhesives after treatment with a hot chromic acid solution. Tensile shear strength of 1270 psi has been achieved with an epoxy-polysulfide adhesive. 

Conventional industrial coatings materials of the thermoset type are usually acrylic, polyester, epoxy, polyurethane or silicone resins dispersed or dissolved in organic or water/ether-alcohol coupling solvents. They are cured with gas convection or electric IR ovens. The raw materials for the polymers come from petroleum feedstocks which are processed or manufactured into a finished coating system. 

In general, plastics are superior to elastomers in radiation resistance but are inferior to metals and ceramics. The materials that will respond satisfactorily in the range of 1010 and 1011 erg per gram are glass and asbestos-filled phenolics, certain epoxies, polyurethane, polystyrene, mineral-filled polyesters, silicone, and furane. The next group of plastics in order of radiation resistance includes polyethylene, melamine, urea formaldehyde, unfilled phenolic, and silicone resins. Those materials that have poor radiation resistance include methyl methacrylate, unfilled polyesters, cellulosics, polyamides, and fluorocarbons. 

In this book I have confined discussion to those polymeric materials which are cured by chemical reaction and which have found widespread application in the construction industry. As such, the book covers materials based on epoxies, polyurethanes, silicones, polysulphides, alkyds and polyesters. In addition, there is a chapter on hybrid polymer systems and one on acrylics. It is true that acrylic emulsions are not strictly thermosetting polymer systems, but their widespread use and importance made their exclusion difficult. These materials find use as coatings, sealants, adhesives, grouts, flooring compounds, repair compounds and waterproofing agents. 

Among the countless number of applications of polymers, the construction industry is one which utilises several polymeric materials. In this book I cover those polymeric materials which are single or bicomponent systems and are cured at ambient temperature either with the aid of curing agents or atmospheric moisture. The various polymers used in manufacturing such products include epoxies, polyurethanes, acrylics, silicones, polysulphides, alkyds and polyesters. As a result of innovation, new technologies exist which utilise more than one polymer in a single product. Such systems are discussed in Chapter 10, on hybrid polymers. 

Polymeric overlays are used on concrete pavements to protect them from dust, excessive wear, cracking, crazing, spalling and to provide an attractive appearance. These materials are applied on concrete pavements in the form of screeds, self-levelling material or floor coatings. Epoxies, polyurethanes and acrylics are commonly used, epoxies being the most commonly chosen. Table 1.4 gives the suitability of these materials for different environments. 

As with epoxies there are many different polyurethanes available, but unlike epoxies, polyurethanes are classified into two categories hydrophilic and hydrophobic. Both react with the water present in a crack substrate to create a chemical reaction that causes the material to expand into a gel or foam that fills the void with a tight seal. Some polyurethanes are so elastic they can stretch by as much as 750% Applicator, 1995). 

Figure 10.9 The reaction pattern for epoxy-polyurethane modifications. Source Wellner, W., Gruber, H. and Ruttmann, G., New solvent free epoxy/polyurethane combinations, publication E 908-8122/850640 published by Bayer AG, Plastics and Coatings Division, D-5090, Leverkusen...

Polycarbonate Conventional adhesives recommended include epoxies, modified epoxies, polyurethanes, acrylics, RTV silicones, cyanoacrylates, one-part elastomers, some epoxy-polyamides, and hot melts (13). 

MAJOR POLYMER APPLICATIONS PP, PE, PS, PA, PVC, PPS, TFE, polyesters, epoxy, polyurethanes, phenolic, silicones... 

MAJOR POLYMER APPLICATIONS epoxy, polyurethane, PMMA, rubber, PVC, unsaturated polyester, sihcone, acrylics... 

MAJOR POLYMER APPLICATIONS PP, PE, PA, PC, PBT, PEEK, PS, epoxy, polyurethane... 

Aettron NX. [Protex] 2,4,6-Tti-dimeth-ylaminmnethylphenol accelerattH for solvent based and powder coating (epoxy, polyurethane). 

Denflex. [Dennis Chem] Plastisols, organosols, epoxies, polyurethanes. 

BlendexO. [OE Specialty] ABS and blmds modifier resin for PVC, epoxies, polyurethane, PC, polyesters. 

Organic coatings may vary from very dense to rather open for water vapour. A dense coating (ideally without flaws), based on epoxy, polyurethane or chlorinated rubber polymers, may block ingress of aggressive species. Nevertheless, the presence of such a layer strongly hinders the evaporation of the moisture that is present in the concrete at the time of treatment. This situation can lead to loss of adhesion to the concrete and thus to a loss of effectiveness of the coating. 

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