GR-N rubber

Butadiene-acrylonitrile rubbers are another group of useful synthetic elastomers. These copolymers were originally developed in Germany where they were found superior in oil resistance to the butadiene-styrene rubbers. Commercially, these materials are produced by free-radical emulsion 

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What is GR-N rubber Explain and describe its preparation and properties. 

With appropriate safety precautions (see Note) to a tared 4 oz. (approximately 125 ml) screw-cap bottle fitted with a GR-N rubber gasket, protected against atmospheric moisture, and cooled with a Dry Ice-acetone bath, are added 8.96 gm of vinyl pelargonate, 15 mg of benzoyl peroxide, and slightly... 

Butadiene and isoprene have two double bonds, and they polymerize to polymers with one double bond per monomeric unit. Hence, these polymers have a high degree of unsaturation. Natural rubber is a linear cis-polyisoprene from 1,4-addition. The corresponding trans structure is that of gutta-percha. Synthetic polybutadienes and polyisoprenes and their copolymers usually contain numerous short-chain side branches, resulting from 1,2-additions during the polymerization. Polymers and copolymers of butadiene and isoprene as well as copolymers of butadiene with styrene (GR-S or Buna-S) and copolymers of butadiene with acrylonitrile (GR-N, Buna-N or Perbunan) have been found to cross-link under irradiation. 

Was first obtained by Moureau (Ref 2). Current methods of prepn include dehydration of S-hydroxypropionitrile or pyrolysis of cyano-ethylacetate(Ref 5). It is somewhat poisonous and sustained exposure to its vapors should be avoided (Refs 4,5,7 8). It is manufd on a large scale for use in making oil-resistant artificial rubber of GR-N type, as well as plastics, etc (Refs 3,4,5 7). Absorption spectra and some other physical props are given in Ref 4 Refs 1)Beil 2,400,(186) [388] 2)... 

By 1931 the first commercially successful rubber substitute, neoprene, was manufactured by DuPont. Among other rubber substitutes later developed in this country were butyl, Buna-N, and GR-S rubber made both from alcohol and from petroleum. Soon after the entry of the United States into World War II, our manufacture of synthetic rubber was stepped up to almost a millions tons a year. 

GDP gross domestic product (see also GNP) GR-N nitrile rubber... 

Uses Flame retardant, plasticizer for PVC and copolymers, PVC plasti-sols, PVC textile coatings, PVAc, cellulosics, polymethyl methacrylate, PS, PP, engineering resins, unsat. polyester, alloys, clear films and sheets. Buna N rubber, acrylic, phenolics food-contact applies. Features Low smoke generation exc. low temp, props. improves processing due to exc. resin solvating power Reguiatory FDA approved for food contact use Properties Colorless clear liq. essentially odorless sol. in most org. soivs. m.w. 362 sp.gr. 1.090 (20/20 C) dens. 9.1 Ib/gal vise. 18 mPas vapor pressure 0.2 mm Hg (150 C) b.p. 462 F (10 mm, dec.) pour pt. -65.2 F flash pt. (COC) 435 F fire pt. (COC) 460 F ref. index 1.508-1.511 8.5% P Phosflex 390 [Akzo Nobel Hatwick Std. Distrib.]... 

Copolymerization of butadiene with acrylonitrile is, like that of styrene, also carried out in emulsion. This may be a discontinuous copolymerization by the cascade process or it may be continuous with withdrawal of the latex from the bottom of the reaction pot. Acrylonitrile and butadiene are used in the azeotropic ratio of 37 63. The copolymers are commercially available under the name of nitrile rubber, or the initials NBR, previously also Buna N or GR-N. They are oil-resistant elastomers. Latices produced with cation-active emulsifiers are used to coat or impregnate textiles and paper. 

The dehydrogenation processes used for the production of butadiene from n-butane and -butenes dirring the development of GR-S rubber were modified in the 1990s for the dehydrogenation of propane to propylene. This compensated for the short supply of steam cracked propylene used to produce polypropylene. The new processes can also be used for the dehydrogenation of other paraflins. 

GR-N Former US symbol for nitrile rubber see 2. Hard proeessing channel black... 

A 1500-cc. flask is fitted with a two-hole rubber stopper carrying a glass tube which ends below the middle of the flask. The second hole is fitted with a common glass stopcock (Note 1). To the flask is added 500 cc. of 6-N ammonium hydroxide (sp. gr. about 0.95), and 100 g. of />-nitrophenylacetic acid (Vol. II, p. 59) is now slowly introduced, with shaking. The flask is then placed in an ice bath, and the mixture saturated with hydrogen sulfide, the temperature being held below 50°. 

Dimethy la mine and Derivatives Dimethylamine, (H3C)2NH, mw 45.08, N 31.07%. col gas at RT and liq at below 7°, sp gr 0.680 at 0°/4, fr p —92.2° extremely flammable and hazardous causes bums sol in w, ale eth. Can be prepd by passing a mixture of ammonia with vapors of methanol over a catalyst, such as silica gel. Has been used in agricultural herbicides and fungicides, synthetic textiles, fiber solvents, rubber vulcanizing accelerators and in missile fuels (Refs 1, 2, 4)... 

Chem. Descrip. Polysiloxane sol n. in cyclohexanone Uses Defoamer tor org. systems incl. chlorinated rubber, vinyl resin, acrylic resin, alkyds, solvent-based coatings Properties Pale to It. yel. Iiq. ether-like odor sp.gr. 0.95 g/cc dens. 7.90 Ib/gal vapor pressure 4 mm Hg flash pt. (Seta) 43 C ref. index 1.450 0.7% NV... 

Chem. Descrip. Tri-n-butyi citrate CAS 77-94-1 EiNECS/ELiNCS 201-071-2 Uses Piasticizer for ceiiuiose nitrate, ethyi ceiiuiose, chiorinated rubber, ceiiuiosic coatings, PVAc, PVB, PVC, PVP, PVdC, poiy(acryiate/meth-acryiate) defoamer in proteinaceous soi ns. improved it. stability in cellulose acetate solvent for household, I I cleaners solvent, film-former, plasticizer in inks, adhesives, coatings food pkg. adhesives Features Environmentally friendly Regulatory FDA 21CFR 175.105 kosher Properties Clear Iiq., essentially odorless sol. in toluene, heptane, < 0.1 g/100 ml water m.w. 360 sp.gr. 1.037-1.045 vise. 32 cps vapor pressure 1 mm Hg (170 C) pour pt. -62 C flash pt. (COC) 185 C ref. index 1.443-1.445 99% assay... 

Properties Wh. coarse powd. 95% thru 325 mesh 6.2 median particie size sp.gr. 2.65 dens. 22.07 ih/gai surf, area 1.3 nf/g oil absorp. 27 ret. index 1.54-1.55 pH 6.5 hardness (Mohs) 6.5 Use Level 30-70% (butfing/polishing), 60 phr (urethane rubber), 60% (adhesives), 65-75% (plastics), 0.5% (antiblock in LDPE film) Toxicology Prolonged inh. of dust may cause silicosis may cause cancer Imwitor 161 [Sasol Germany Sasol N. Am.]... 

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