Polyacrylate elastomers

Polyacrylate elastomers find limited use in hydrauhc systems and gasket apphcations because of their superior heat resistance compared to the nitrile mbbers (219,220). Ethylene—acrylate copolymers were introduced in 1975. The apphcations include transmission seals, vibration dampers, dust boots, and steering and suspension seals. Further details and performance comparisons with other elastomers are given in reference 221 (see also Elastomers, SYNTHETIC-ACRYLIC ELASTOTffiRS). 

E. Chang and E. Ma22one, "A New Non-Postcure Curative Package for Polyacrylate Elastomers", paper presented atMCA BjibberDivisions Detroit, Mich., Oct. 17—20, 1989. 

Grafted copolymers obtained by VCM polymerisation and polyacrylic elastomer grafting, give high bulk density resins for products with high impact strength suitable for outdoor applications. The separate addition of acrylate impact modifiers to the PVC formulation is covered in Section 4.5.2. 

Diak [Du Pont]. TM for a series of rubber accelerators used to vulcanize Viton fluoroelas-tomer and polyacrylate elastomers. 

Gahlmer, F. H. and Nleske, F. W., "Hydrolytic Stability of Urethane and Polyacrylate Elastomers in Humid Environments," Urethanes In Elastomers and Coatings (articles from the Journal of Elastoplastlcs), pp. 6-20, Technomlc Publ. Co., Inc., Westport (1973). 

Trimethyixtadecylammonium bromide. Accelerator for Nipol AR and HyTemp 4050 series polyacrylate elastomers, Nippon Zeon. 

Uses Accelerator for polyacrylate elastomers base, antistat, germicide for hair rinses and treatments... 

HyTemp Polyacrylate elastomer, curable or not Nippon Zeon Co., Ltd. 

The company also makes PVC lubricants and modifiers (hquid and sohd ester lubricants, hydrocarbon waxes, polyacrylate elastomer impact modifiers, metal soaps, fatty acids and their derivatives) and plasticisers (epoxidised monoester and epoxidised soybean oil), together with acrylic process aids and amide wax antiblocking agents. 

Polyacrylate elastomers -20—56 Free-radical (emulsion, suspension)... 

A NEW CROSSLINKING REACTION OF POLYACRYLIC ELASTOMER BY ONIUM SALT CATALYST... 

Polyacrylic elastomer is a chemically saturated polymer of acrylic acid esters. Since esters are rather inert, other groups such as epoxy, halogen and carboxyl must be incorporated into the polymer to introduce sites for curing. We have studied the effect of various ammonium and phosphonium salt catalysts on the rate of crosslinking of polyacrylic elastomers which contain carboxyl and epoxy groups as cure-sites. We find that the catalytic activity of onium salts correlates with nucleophilicity of their anions. 

The onium salt catalyzed reaction of a polyacrylic elastomer containing epoxy groups as cure-sites was enhanced by the addition of a dicarboxylic acid as an external crosslinking agent. This enhancement of cure rate decreased by increasing the alkylene chain length of the dicarboxylic acid. This behavior can be explained by the dissociation constants, K, and K, of... 

Polyacrylic elastomers contain chemically saturated backbones. Since these rubbers are not unsaturated, they cannot be vulcanized with conventional sulfur cure systems. Monomers with cure-sites must therefore be introduced into the polymer chain. 

Various types of monomers have been used to introduce cure-sites into polyacrylic elastomers. Polyacrylic elastomers containing active chloride, epoxy, and carboxyl groups as active cure-sites have been developed for industrial applications. Polyacrylic elastomers which contain epoxy groups are vulcanized with ammonium salts and dithiocarbamate salts, whereas elastomers which contain active chloride are vulcanized with sulfur-metal soap, organic amines, etc. 

Crosslinking of polyacrylic elastomers through carboxyl group is well established in rubber technology. The crosslinking mechanism of polyacrylic elastomers which contain both carboxyl and epoxy groups as cure-sites has also been studied for the low molecular weight polymers. ... 

In this paper, we describe the effect of various onium salt catalysts on the crosslinking reaction of polyacrylic elastomers which contain both... 

The polyacrylic elastomers were prepared by emulsion polymerization. The monomers, water, emulsifiers (i.e., sodium lauryl sulfate and sodium salt of polymerized naphthalene sulfonic acid), tetrasodium ethylenediaminetetraacetate, and sodium ferric salt of ethylenediaminetetraacetic acid were charged to the reactor vessel equipped with an agitator. The temperature of the reactor vessel was controlled at 10 C. The reactor was evacuated to remove air, closed and the emulsion agitated. Sodium sulfate, sodium formaldehyde sulfoxylate and paramenthane hydroperoxide were then charged to the reactor. The reaction time was 12 hours. The conversions to copolymers were 93 - 97% (Table 1). 

In crosslinking reaction of polyacrylic elastomer which contains carboxyl and epoxy groups as cure-sites by onium salt catalyst, the effective center is an active carboxylate onium salt. The catalytic activity showed good agreement with the nucleophilicity of the counter anion of onium salt and followed I > Br > Clo... 

Zeon Chemicals Announces New Polyacrylate Elastomer, news item, August 14,... 

Polyacrylate elastomers may consist of one or more of the following monomers ethyl acrylate, EA butyl acrylate, BA and methoxy ethyl acrylate MEA, the structures of which are given in Figure 5.1. These are coupled with cure sites, which may be reactive halogens, epoxy or carboxyl groups, or combinations thereof, as seen in Figure 5.2. [1,6,11]. 

Polyacrylate elastomers have lower viscosities than most other elastomers and also are more thermoplastic, hence it is essential when mixing to maintain full cooling on all mixing surfaces and incorporate reinforcing fillers very early in the mixing cycle in order to obtain good dispersion. This applies to both internal and mill mixing. 

---