Chemical Resistance of PVC

Ta bl e A. 2 6 Chemical resistance of PVC diluted = aqueous solution, wt.% 10%, solution aqueous solution, wt.% 10% (all %-values assume water as solvent [243]) 

Aminobenzene sulfonic acid (sulfanilic acid), solution 

MIIIIIIUIMUIM MUUIUbmUcUC , saturated Ammonium formate, saturated . J rt 20 A . J rt 20 A  

Benzilic acid, technical grade Benzine, technical grade 

Beryllium chloride, saturated Beryllium fluoride Beryllium sulfate, saturated Betaine hydrochloride Betaine, technical grade 

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Chemical resistance of PVC also depends on its processing conditions, namely gelation. Also, process instabilities may lead to the differences in the degree of gelation within the material, leaving some areas more vulnerable to the chemical attack. ... 

Chemical resistance of PVC articles depends on the type and amount of components used in the formulation, such as fillers, plasticizers, lubricants, and others. PVC-P is less resistant than PVC-U against many chemicals. 

TableA.26 Chemical resistance of PVC diluted = aqueous solution, wt.%< 10%, solution ...

Nitrile mbber finds broad application in industry because of its excellent resistance to oil and chemicals, its good flexibility at low temperatures, high abrasion and heat resistance (up to 120°C), and good mechanical properties. Nitrile mbber consists of butadiene—acrylonitrile copolymers with an acrylonitrile content ranging from 15 to 45% (see Elastomers, SYNTHETIC, NITRILE RUBBER). In addition to the traditional applications of nitrile mbber for hoses, gaskets, seals, and oil well equipment, new applications have emerged with the development of nitrile mbber blends with poly(vinyl chloride) (PVC). These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile mbber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile mbber in outdoor applications for hoses, belts, and cable jackets, where ozone resistance is necessary. 

Most metals, concrete, and other constmction materials are corroded by hydrobromic acid. Suitable materials of constmction include some fiber glass-reinforced plastics, some chemically resistant mbbers, PVC, Teflon, polypropylene, and ceramic-, mbber-, and glass-lined steel. Metals that are used include HasteUoy B, HasteUoy C, tantalum, and titanium. The HasteUoys can only be used at ambient temperatures. Liquid hydrogen bromide under pressure in glass at or above room temperature can attack the glass resulting in unexpected shattering. 

This is used most often in process plants. It is a tough, low-cost material with probably the widest range of chemical resistance of any of the low-cost plastics. On a volume basis, PVC is more favorable than polypropylene because the modulus of PVC is considerably higher than that of polypropylene, so it will form more rigid structures when used at the same thickness. On a weight basis it is not as favorable as PVC because it has a specific gravity of 1.4 compared with 0.92 for polypropylene. 

Low-density polyethylene (polythene) is a relatively cheap, tough, flexible plastic. It has a low softening point and is not suitable for use above about 60°C. The higher density polymer (950 kg/m3) is stiffer, and can be used at higher temperatures. Polypropylene is a stronger material than the polyethylenes and can be used at temperatures up to 120°C. The chemical resistance of the polyolefines is similar to that of PVC. 

The chemical resistance of flexible PVC can be strongly reduced and the absorption of water can be appreciably higher. 

Chemical resistances of the PVC laminate and polypropylene imported sheets can be obtained from Dinamit Nobel, Rockleigh, NJ. 

There are many similarities in the chemical resistance of CPVC and PVC. However, care must be exercised because there are differences. Overall, the corrosion resistance of CPVC is somewhat inferior to that of PVC. In general, PVC is inert to most mineral acids, bases, salts, and paraffinic hydrocarbons. 

Type 1 PVC (unplasticized) resists attack by most acids and strong alkalies, gasoline, kerosene, aliphatic alcohols, and hydrocarbons. It is particularly useful in the handling of hydrochloric acid. The chemical resistance of type 2 PVC to oxidizing and highly alkaline materials is reduced. 

PVC adhesives, usually consisting of solutions of post-chlorinated PVC in methylene chloride, are used in the case of inorganic acids as flow-through media in PVC pipe because of their better chemical resistance. Since PVC adhesives have no gap-filling properties a special application technique is required. This priming method is little used today. 

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