Vamac elastomers

A Review of Fast-Cure Systems for VAMAC Elastomers, Technical Bulletin E.I. DuPont de Nemours and Company, Inc., Document reference VAM020507, 2002. 

Bailor, F.V. Vamac elastomers - versatilty for auto applications. Rubber World 180, 1979. Blow, C.M., Exley, K., South Wart, D.W. Penetration of liquids in rubber. J IRI 3(1), 1969. Brown, R.P., Morrel, S.H., Norman, R.H. Tensile stress relaxation. J Inst Rubber Ind 4, 1973. Brumback, M.E., Clade, J.A. Airborne Rubber Seals Industrial maintenance. Thomson Delmar Eearning, 2003. 

Commercial Forms. Eour different base polymers of VAMAC ethylene—acryhc elastomer are commercially available (Table 1). Until 1990, existing grades of ethylene—acryhc elastomers were based on a single-gum polymer. VAMAC G, defined as a terpolymer of 55% methyl acrylate, ethylene, and a cure-site monomer (5). In 1991, a higher methyl acrylate terpolymer, VAMAC LS, was introduced. The composition of this polymer was specifically chosen because it significantly increases the oil resistance of the polymer while minimizing losses in low temperature fiexibihty (6). 

Terpolymers in which the acrylate monomer is the major component are useful as ethylene-acrylate elastomers (trade name Vamac) [Hagman and Crary, 1985]. A small amount of an alkenoic acid is present to introduce sites (C=C) for subsequent crosslinking via reaction with primary diamines (Sec. 9-2d). These elastomers have excellent oil resistance and stability over a wide temperature range (—50 to 200°C). They are superior to nitrile and chloroprene rubbers. Although not superior to silicone and fluorocarbon elastomers, they are less costly uses include automotive (hydraulic system seals, hoses) and wire and cable insulation. 

Vamac . [DuPont DuPont UK] Ediyl-enefacrylic elastomer for hose, tubing, boots, seals, wire and cable, undeihood autmnotive, heavy equipment and in-dustrisd parts, vibration dampers, seals, gaslmts, misc. molded items, and [Pg.394]

Rubber Blends For Automotive Applications. The ionomers from Exxpro elastomer can be blended with other elastomers such as Neoprene(CR), Nitrile(NBR), and Acrylics(VAMAC) for selected automotive applications, e.g., hoses, air springs, and belts. 

Ethylene acrylic elastomer (Vamac G) Irganox 1010 Zinc borate... 

Vamac Ethylene-acrylic elastomer, curable with diamines E. I. du Pont de Nemours Co. 

Toughened cyanoacrylate adhesives containing random copolymeric elastomers have been patented. The only elastomer whose performance has been quantified is an ethylene-methyl acrylate copolymer sold by Du Pont under the name Vamac B-124. Several other elastomers are said to be useful tougheners, but no details have been given beyond solubility data. 

Table 1. Vamac Ethylene-Acrylic Elastomer Polymers...

H. J. Barager and L. C. Muschiatti, Vamac Ethylene Acrylic Elastomers for Demanding Automotive Applications, Paper No. 189, American Chemical Society Rubber Division, Orlando, Fla., Sept. 1999. 

J. F. Hagman, Vamac G Gum Ethylene/Acrylic Elastomer, Bulletin E-52096, DuPont Polsmiers, Stow, Ohio, Sept. 1978. 

C. Williams, Vamac Ethylene/Acrylic Elastomer, A Survey of Properties, Compounding and Processing, Bulletin H-34753, DuPont Polymers, Stow, Ohio, Jan. 1992. 

Thermoplastic elastomer TPV, such as Forprene, Santoprene, and Uniprene, are increasingly used for air intake ducts for turho air intake dncts, Vamac ethylene acryhc elastomers represents thermosetting synthetic rubbers with higher temperature properties for underhood applications. 

Vamac Product Data Sheet, DuPont Viton Product Data Sheet, DuPont Dow Elastomers. 

FIGURE 6.1 Stmctures of Vamac ethylene acrylic elastomers. 

Vamac polymers are halogen- tee and therefore do not promote corrosion and are suitable for use in noncorrosive, flame-retardant applications. The permeability of Vamac to gases is low, compared with that of butyl mbber. In addition, AEM compounds have good adhesion to a variety of metals, fibers, and other elastomers. Mineral-filled compounds of Vamac can be brightly colored and are capable of maintaining their color quality after thermal aging. 

As with most elastomers, various fillers have different effects on the properties of the compoimd. Because of the potential for the formation of ionic crosslinks with the terpolymer, some fillers are not suitable for use with terpolymers. Table 6.9 is a brief overview of filler performance when incorporated into Vamac. 

Effective plasticizers for Vamac include monomeric esters, polymeric esters, and polymeric ether-ester types. Table 6.13 lists the plasticizers typically used for Vamac. The petroleum-based plasticizers commonly used in most elastomers are... 

Source D.A. Kotz, T.M. Dobel. Stress relaxation of ethylene/acrylic and other gasket materials in automotive fluids. Society of Automotive Engineers International Congress and Exposition, Detroit, Michigan, February/March 1994, Paper No. 940959 Basic principles for the conqtounding and processing of Vamac dipolymers. Dufont Dow Elastomers Technical Information Bulletin H-68560. 

Source Basic principles for the compounding and processing of Vamac dipolymers. DuPont Dow Elastomers Technical Information Bulletin H-68560. 

W.M. Stahl, Fluid resistance of Vamac . DuPont Technical Bulletin EA-510.1 (R2). A.E. Hirsch and R.J. Boyce. Dynamic properties of ethylene/acrylic elastomer A new heat resistant rubber. Proceedings of the International Rubber Conference, Brighton, England, May 1997. DuPont Technical Bulletin C-EA-53C.G04. 

Struktol WB 42 at a 1 % level, combined with 1 % stearic acid, is a good combination for general purpose use in peroxide-cured AEM ethylene acrylic elastomer compounds. Vamac AEM stocks using hexamethylene diamine carbamate (Diak No. 1) as the curative, requires 1% stearic acid plus 0.3% of a stearamide such as Armeen 18D from Akzo and 0.8% of Struktol WS 180. These chemicals act as coagents for mill release. Struktol WB 42, Struktol WS 180, and Armeen 18D also serve as mold release agents. 

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