Hardening agent

Although its principal use is as a hardening agent for platinum, iridium is also used to make crucibles and devices requiring high temperatures. It is also used for electrical contacts. 

Polymers. AH nitro alcohols are sources of formaldehyde for cross-linking in polymers of urea, melamine, phenols, resorcinol, etc (see Amino RESINS AND PLASTICS). Nitrodiols and 2-hydroxymethyl-2-nitro-l,3-propanediol can be used as polyols to form polyester or polyurethane products (see Polyesters Urethane polymers). 2-Methyl-2-nitro-l-propanol is used in tires to promote the adhesion of mbber to tire cord (qv). Nitro alcohols are used as hardening agents in photographic processes, and 2-hydroxymethyl-2-nitro-l,3-propanediol is a cross-linking agent for starch adhesives, polyamides, urea resins, or wool, and in tanning operations (17—25). Wrinkle-resistant fabric with reduced free formaldehyde content is obtained by treatment with... 

Potassium alum, which also occurs naturally as the mineral kalinite [7784-24-9], KAl(SO 2 12H20, sp gr 1.75, is used ia tanning skins, as a mordant ia dyeiag, and ia the pharmaceutical and cosmetic iadustries (see Pharmaceuticals Cosmetics). It is used as a styptic pencil and as a hardening agent and set accelerator for cement and plaster. The ACGIH threshold limit value TWA is 2 mgAl/m (1 ). 

Sodium chlorite oxidation of com and rice starches is recommended for the production of textile sizes (101) and oxidized starch is recommended as a hardening agent in the immobilization of microbial cells within gelatin (102). 

The number of hardening agents used commercially is very large and the final choice will depend on the relative importance of economics, ease of handling, pot life, cure rates, dermatitic effects and the mechanical, chemical, thermal and electrical properties of the cured products. Since these will differ from application to application it is understandable that such a wide range of material is employed. 

Acid anhydride and amine hardening agents, Adhesives, plastics, moulding resins and... 

Fizier-fliissigkeit, /. fixing liquid or liquor, -mittel, n. fixing agent, fixative hardening agent, -natron, n. sodium thiosulfate, -salz,... 

Sb and Ba are present in the airborne gunshot residue expelled from all of the brands of 0.22 cal ammo. A chemical analysis of the primer. of the Western brand gave a Ba to Sb ratio of 65, whereas the same ratio obtained from the data in Table 11 is 2.6. The authors conjecture that this additional Sb left in the air came from the vaporized bullet Pb which contains a large amt of Sb as a hardening agent... 

The crosslinking efficiency of many peroxide-initiated free radicals is low. These labile radicals can be converted to more stable radicals by contact in situ with polyfunctional monomers to form a three-dimensional network. Crosslinking efficiency is thus increased by some 20%. In addition, these materials act as plasticisers during processing and in some cases also act as hardening agents. 

Uses. Beryllium metal sheet or wire ceramics hardening agent in alloys used especially in the electronics field... 

Uses. Production of methylene diphenyl diisocyanate (MDI), which is used to produce polyurethanes hardening agent for epoxy resins, anticorrosive materials, printed circuit parts, dyestuff intermediates, filament-wound pipe, and wire coatings... 

Uses. Reactive free radical-generating chemical used as a curing agent for unsaturated polyester resins hardening agent for fiberglass-reinforced plastics manufacture of acrylic... 

Bipyridine resembles nicotine in its pharmacological properties but is not as active. The 3,4 -bipyridine derivative 113 known as amrinone and its relatives are of interest as cardiotonic agents. 4,4 -Bipyridine has been tested as an insecticide, but it is not of practical value.It is used in the study of the electrochemistry of cytochrome c and acts as a polymerization catalyst or hardening agent for various resins. l-Hexyl-4,4 -bipyridinium salts are especially effective as electron carriers in photochemical hydrogen producing systems. l,l -Dimethyl-4,4 -bipyridinium (92 R = R = CHj) and l,l -dibenzyl-4,4 -bipyridinium... 

Ferroboran. A ferro-alloy averaging 16.2% boron used as hardening agent in special steels. It also is an efficient deoxidizer. 

HDI is the common name for hexamethylene diisocyanate. It is also known as 1,6-hexamethylene diisocyanate, 1,6-diisocyanatohexane, Mondur HX, and Desmodur H. It is a pale yellow liquid with a strong odor. HDI is found in hardening agents for automobile paints. 

HDI is most often found in air near locations where spray paints that contain it as a hardening agent are used. HDI in the air can enter the soil and water. HDI can also enter the soil if products containing it are dumped directly onto the soil. HDI can enter the water supply by washing out of soil that contains it or if products with HDI are dumped directly into water. Once it is in soil or water, HDI does not easily evaporate, so general air pollution is not expected. HDI breaks down very quickly in water or sunlight, so it probably will not build up in the environment. 

Falsafi et al. (4) prepared polymerizable compositions of arylsulfmate salts containing ethylenically unsaturated substitiuents that were used as hardenable agents in dental compositions. 

Tris(chloromethoxy)propane appears not to have been produced commercially, although its use as a resin-hardening agent was investigated (lARC, 1977). 

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