Chemical and Alkali Resistance

As cheap and easy to process materials, imsatiuated polyester resins are widely used as coatings as well as reinforced composites for the manufacture of for example water pipes, hulls of boats, yachts and large ships, solvent reservoirs, tanks, and other uses. It is well known that UPRs contain ester groups (especially maleate/fumarate and phthalate) in the chain and thus exhibit a relatively high sensitivity to hydrolysis. The hydrolysis can initiate cracking, which leads to macroscopic cracks. Vinyl esters containing methacrylic ester groups exhibit much better hydrolytic stability. 

It was found that the flexibilization of chemically resistant UPRs resulted in an increase in the chemical resistance [126]. The comparison between stan- 

The effects of solvent exposure on the viscoelastic properties of several vinyl ester resins (phenohc-novolac epoxy, propoxylated bisphenol-A fu-marate, urethane and bisphenol-A epoxy based) and various unsaturated polyester resins (terephthalic or isophthaUc acid with a standard glycol based) containing 10wt% glass fiber were studied [130]. The results of dynamic mechanical analysis showed that the influence of exposure time to the solvent as well as the influence of temperature depended on the styrene content and chemical composition of the studied resins, while the amount of cobalt octoate used for the synthesis as the accelerator had no influence on the viscoelastic properties of the prepared materials after solvent exposure. It was also found that not fully cured urethane vinyl ester and the terephthahc acid-based unsaturated polyester resins showed excellent resistance to sulfuric acid exposure. However, interactions between the tested resins and petroleum could possibly occur through intermolecular bonding between the non-polar chains of the cured resins and the solvent. 

The microstructure of zso-phthalate polyester films before and after exposure at room temperature to an alkaline solution was studied using tapping mode atomic force microscopy (AFM) [133]. The results of structural characterization as well as chemical analyses using attenuated total reflection FT-IR, total carbon analysis and liquid chromatography-mass spectroscopy showed that the base-catalyzed hydrolysis of polyester was a heterogeneous process. The formation of pits occurs as a result of hydrolysis and the number and size of pits increases with exposure time. 

The enzyme-catalyzed hydrolysis of phthalic units containing polyesters could be used as a potential tool for the block length sequence analysis [134], Thus, copolyesters undergo two kinds of degradation process in the presence of lipase from Chromobacterium viscosum a fast and selective enzymatic hydrolysis of the fumaric ester functions and a slow but non-selective imcat-alyzed hydrolysis of fumaric and phthalic ester functions. 

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Although yellow iron oxide pigments give a series of rather dull colors, they have excellent properties relatively easy to disperse, nonbleeding, good opacity, fine heat resistance, and low cost. Since their chemical and alkali resistance is excellent, they can be used in both water- and solvent-based paints. 

It is stable in the presence of water, alkalies, acids, or actively-reacting chemicals and is resistant to oxidation. Will not corrode metals. Its vapors are poisonous... 

Leather 220 Low cost. Limited chemical and heat resistance. Not recommended against pressurized steam, acid or alkali solutions. 

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage hazardous polymerization has not been reported stable to acids and alkali resistant to oxidation but are subject to photodechlorination when exposed to sunlight will attack some forms of plastics, rubber, and coatings can react with strong oxidizing agents FP (176°C, 349°F) LFL/UFL (data not available) AT (data not available). 

Furane resins, derived from oats, are worthy of mention because of their outstanding chenaical resistance, which makes them good candidates for use as liner cements in chemical vessels and pipes. A combination of chemical and heat resistance is especially useful - siUcone resins have thermal stability up to 200-370°C but they are susceptible to steam and strong alkali. 

Features Chemically bonds to building material vapor permeability UV-and alkali-resist. 

Customarily used membrane materials show good chemical resistance even in the severe conditions of an industrial environment. Hydrolysis and alkali resistance are decisive for ageing resistance. 

The significant characteristics of EPDM sheeting, such as, its resistance to acids and alkalies, resistance to vegetable and animal fat, being unaffected by toxic chemicals, and with good mechanical properties make its way as an effective lining barrier for effluent treatment plants. 

Every chemical attack on glass involves water or one of its dissociation products, i. e. H+ or OH- ions. For this reason, we differentiate between hydrolytic (water), acid, and alkali resistance. In water or acid attack, small amounts of (mostly monovalent or divalent) cations are leached out. In resistant glasses, a very thin layer of silica gel then forms on the surface, which normally inhibits further attack (Fig. 3.4-8a,b). Hydrofluoric acid, alkaline solutions, and in some cases phosphoric acid, however, gradually destroy the silica framework and thus ablate the glass surface in total (Fig. 3.4-8c). In contrast, water-free (i. e. organic) solutions do not react with glass. 

Epoxy resins can be formulated with a wide range of properties. These medium to high priced resins are noted for their adhesion. Epoxy linings provide excellent chemical and corrosion resistance. They exhibit good resistance to alkalies, nonoxidizing acids, and many solvents. Typically, epoxies are compatible with the following materials at 200°F/93°C unless otherwise noted ... 

C.700 HIGH ALUMINA ceramics C.800 OXIDE CERAMICS The standard also defines six classes of glass insulating materials, based on composition G.lOO alkali-lime-silica G.200 and G.300, borosilicates (chemically and electrically resistant respectively) G.400 alumina-lime-silicates G.500 lead oxide alkali silica G.600 barium oxide alkali silica. 

Chemical properties include swelling (or solubility) resistance, moisture resistance, acid resistance, and alkali resistance. 

Excellent chemical and moisture resistance. Glass fibers do not absorb moisture, rot, or mildew and resist all solvents, and most acids and alkalis. 

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