Acid-resistant epoxy

High-build abrasion-resistant epoxy Acid-resistant epoxy High-build, recoatable epoxy Solvent-free epoxy 1... 

Epoxy Mortars Epoxies are the strongest resin mortars, have the best bond strength to other CRM materials, and resist many solvents, mild to moderate acids, non-oxidizing and alkaline media. Their useful pH range is about 2-14, and their thermal limit is approximately 230°F. Besides their excellent alkali and dilute acid resistance, epoxy mortars handle many organic chemicals and sodium hypochlorite at low temperatures. Epoxies should not be exposed to acetic acid and its esters. Epoxy mortars have the best physical and mechanical properties of all the resin mortars. 

Acid-resistant epoxy 55 75-150 3 h 20 h Two components, poiyamine cured... 

Epoxy resin cements are specifically intended for resistance to caustic alkalis and organic solvents, but they also have fair acid resistance. They have excellent bond strength to other materials including ceramic and concrete. The corrosion resistances of the cements described above are given in Table 3.40. 

The most commonly used stabilizers are barium, cadmium, zinc, calcium and cobalt salts of stearic acid phosphorous acid esters epoxy compounds and phenol derivatives. Using stabilizers can improve the heat and UV light resistance of the polymer blends, but these are only two aspects. The processing temperature, time, and the blending equipment also have effects on the stability of the products. The same raw materials and compositions with different blending methods resulted in products with different heat stabilities. Therefore, a thorough search for the optimal processing conditions must be done in conjunction with a search for the best composition to get the best results. 

Acid waste waters from silicone production enter neutraliser 9, a concrete container with two agitators, lined with acid-resistant tile from epoxy resin. Here the waste waters are neutralised with lime milk, which is automatically sent from reservoirs 6 with pumps 8. The pumps automatically switch off when pH in the neutraliser is 8-10 and switch on when pH is below 5. Neutral waste waters continuously self-flow through a collector into receiving reservoir 10 as they accumulate, they are automatically sent with pumps 11 for averaging and mechanical purification. 

Aromatic amines are widely used as curing agents for epoxy resins. However, they are not used as widely in adhesive formulations as they are in composites, molding compounds, and castings. They offer cured epoxy structures with good heat and acid resistance. 

TABLE 11.23 H2S04 Acid Resistance of Epoxy Adhesive Formulations Cured 1 Week at 25°C32... 

Systems cured with DETA and TETA generally have excellent resistance to aqueous sodium hydroxide even at 50% concentration and 80°C. Their resistance to 25 percent sulfuric acid, 23 percent hydrochloric acid, and 25 percent chromic acid is also very good up to 80°C. Strong organic acids such as acetic acid generally attack DETA and TETA cured epoxy resins as well as strong (40%) nitric acid. Resistance to intermittent solvent exposure is excellent however, long-term immersion in any aliphatic solvent such as kerosene is not recommended. 

Bisphenol F epoxy resins provide similar chemical resistance to that of bisphenol A based epoxies. However, there is some improvement to acid resistance in the former, depending on the curing agent used. With bisphenol F epoxy resins it is possible to have higher filler levels and faster bubble release because of their relatively low viscosity (Figure 2.4). 

The acid resistance of epoxy phenolics to continual immersion conditions would generally be poor to fair. Special formulations are available to provide resistance to dilute sulfuric, hydrochloric, nonoxidizing mineral acids, and fatty acids. Many systems are available for resistance to spillage and fumes from most acids with the exception of nitric, formic, chromic or hydrofluoric. 

The mortar may be applied to properly prepared concrete or steel substrates by usual acid-resistant bricklaying methods. An epoxy, urethane asphalt, bi-tumastic, polyester or vinyl ester membrane is required behind the block to ensure corrosion protection of the substrate. Because the mortar joints are rigid, a system of expansion/contraction joints, usually filled with ceramic paper, must be designed to prevent cracks. 

Of finishes used outside, the polymers that can offer the best protection against acid deposition are those not containing acid-sensitive groups such as esters. Inclusion of acid resistant paint binders such as vinyls, urethane, and epoxies would produce acid resistance only if the other components are also acid resistant. Saponification of esters catalyzed by hydroxyls formed during corrosion of steel substrates may also degrade polyesters (7). 

Reactions of model compounds studied bv DSC The development of acid based curing agents, to cure a new generation of UV resistant epoxy resins, required a study of the epoxy/acid reaction with model compounds. A monofunctional, liquid epoxy resin (CARDURA E5) was used as model resin the selected model acids are listed in Table 1.7. 

Anhydrides. Polyanhydrides and not monoanhydrides must be used to cure epoxy surface coatings. They are used in powder form for powder coatings and in solution for can coatings both forms are hot curing. The films have a good acid resistance, and do not impart an undesirable taste to foods. 

The raw gas contains humid mixtures of SOj and SO3 and condensing sulfuric acid at temperatures of 80-100°C. The cleaned gas contains the same contaminants, but at much lower concentrations [6]. Both duct systems have been successfufly manufactured from GRP using an acid-resistant novolac epoxy vinyl ester resin. Large diameters are often used for... 

Recent research by Bergman [8] at the Swedish Corrosion Institute has demonstrated that in the gas/acidic sections of absorbers, novolac epoxy vinyl ester resins associated with acid-resistant glass types perform best, while in the high pH liquid-containing section, bisphenol-A epoxy vinyl... 

Uses Epoxy tiexibiiizer/diiuent, acid resist, aid, vise, reducer in fioor and surfacing compds., VOC-compiiant surf, coatings, tooiing resins, adhesives, eiec. appiics., anticorrosive coatings tor marine and industriai... 

Chem. Desaip. Epoxy ester in xylene and fatty acids Uses Epoxy for high-quality zinc-rich and anticorrosive paints, air-diying and stoving primers and topcoats Features Fast drying and exc. water resist. 

Another use of cement is that of jointing and bedding material for tiles and bricks of all types, and cement in this context includes many synthetic materials which are produced to meet particular conditions. For example sodium silicate and potassium silicate cements are acid resisting, whereas rubber latex, furan resin, and epoxy resin cements are both acid and alkali resisting. In most cases the suitability of a particular cement for a given condition should be carefully checked with the manufacturer before it is used. 

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