Polyacrylate elastomers applications

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. 

Polyacrylate elastomers find limited use in hydraulic systems and gasket applications because of their superior heat resistance compared to the nitrile mbbers (219,220). Ethylene—acrylate copolymers were introduced in 1975. The applications 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,... 

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. 

P.E. Manley and C.T. Smith, Improved Heat Compression Set Resistant Polyacrylate Elastomers—Part B Applications in Engine and Automatic Transmission Fluids Requiring Low Compressive Stress Relaxation, 158th Meeting, Rubber Division, ACS, October 17-20, 2000. 

P.E. Manley, New Technology for Polyacrylic Elastomers in Automotive Sealing Applications, SAE Meeting, Detroit, February 26-29, 1996. 

In an initial study, various antioxidants were evaluated in hydrogenated nitrile-butadiene rubber (HNBR), polyacrylic elastomer (ACM), and ethylene-acrylic elastomer (EAM), polymers which are frequently used in applications requiring high heat and oil resistance. Compounds of these elastomers were first immersed in ASTM 901 Oil to remove any soluble antioxidants that could be extracted in service, and later heat aged up to 21 days at 177°C in air. Similar agings were performed with samples placed in... 

Diacyl peroxides are used in a broad spectmm of applications, including curing of unsaturated polyester resin compositions, cross-linking of elastomers, production of poly(vinyl chloride), polystyrene, and polyacrylates, and in many nonpolymeric addition reactions. 

Surface treatments consist of washing with solvent, abrading, or, in the most demanding applications, cyclizing with acid. The most common elastomers to be bonded in this way include nitrile, neoprene, urethane, natural rubber, SBR, and butyl rubber. It is more difficult to achieve good bonds with silicones, fluorocarbons, chlorosulfonated polyethylene, and polyacrylate. 

Ozone-resistant elastomers which have no unsaturation are an excellent choice when their physical properties suit the application, for example, polyacrylates, polysulfides, silicones, polyesters, and chlorosulfonated polyethylene (38). Such polymers are also used where high ozone concentrations are encountered. Elastomers with pendant, but not backbone, unsaturation are likewise ozone-resistant. Elastomers of this type are the ethylene—propylene—diene (EPDM) mbbers, which possess a weathering resistance that is not dependent on environmentally sensitive stabilizers. Other dastomers, such as butyl mbber (HR) with low double-bond content, are fairly resistant to ozone. As unsaturation increases, ozone resistance decreases. Chloroprene mbber (CR) is also quite ozone-resistant. 

Data have been published dealing with successful applications of HAS in stabilization of other polymers than PO elastomers, styrenic polymers, polyamides, polycarbonates, polyacetals, polyurethanes, linear polyesters, thermoplastic polyester elastomers, polyacrylates, epoxy resins, poly(phenylene oxide) or polysulfide [12]. In spite of their basicity, HAS may also be used for stabilization of PVC. This application includes less basic derivatives of piperidine and 1,4-dihydropyridine [12,13,145,146]. 

The above criteria were employed to select several commercially supplied Class PS elastomers for laboratory screening by employing selected tests taken from National Bureau of Standards NBSIR 77-1437(j4) and ANSI/ASTM D-3667-78 specifications for "Rubber Seals Used in Flat-Plate Solar Collectors". Four silicone, three EPDM, two fluorocarbon, three epichlorohydrin, one ethylene-acrylic, one polyacrylic, one chlorosulfonated polyethylene, one bromobutyl and two butyl rubbers were studied in these screening tests. These materials are identified in Table I and those compositions which were revealed by their manufacturers are shown in Table II. Undoubtedly some materials which should have been included were omitted however, we hope that this sampling will provide an indication of the applicability of a wide range of materials for use as sealants in thermal solar collectors. 

The fragile character of rigid amorphous polymers is an important limitation in many potential applications. The problem is circumvented by blending with an elastomer phase. This can produce materials capable of resisting impact. Hence, car rear lights are made of poly(methyl methacrylate) strengthened by addition of a polyacrylate with Tg around —40°C. 

To achieve good toughness, required for many applications, impact modifiers are added to PVC. Chlorinated polyethylenes, ethylene-vinyl acetate copolymers, styrene-methyl methacrylate grafted elastomers, vinyl rubbers, and polyacrylates are the most frequently used (316). These polymers are blended together with other additives. Blending conditions are extraordinary important for morphology control and consequently for final properties of the blends. 

NR and plastic blends have been reported for the preparation of thermoplastic NR blended systems. Many types of plastics have been blended with NR, such as polyethylene, polypropylene, polystyrene, " polyacrylates or polyacrylic acid, and poly(methyl methacrylate). These thermoplastic NRs provide new materials with different properties that range from a soft elastomer to a semi-rigid NR plastic for various industrial applications.In addition, NR can improve the toughness of brittle thermoplastic materials. The NR and thermoplastic blends express greater ductility and impact strength at low temperatures. The requirements for certain mechanical and physical specifications can be achieved by optimizing the blended compositions and selecting the most suitable thermoplastics. 

Elastomers containing polyepichlorohydrin, also known as ECO, CO, or GECO according to ASTM, offer an excellent balance of properties, combining certain desired dynamic properties of namral mbber (NR), with much of the fuel, oil, and chemical resistance of other specialty elastomers such as nitrile (NBR), polyacrylate (ACM), and neoprene (CR) mbbers. The combination of the basic properties of oil, fuel, heat, low-temperature flexibility, and ozone resistance imparted by the saturated main chain and the chlorine groups, coupled with low permeability, makes polyepichlorohydrin a very useful elastomer for automotive applications. Specific applications include fuel hoses, emission tubing, air ducts, seals, and diaphragms. 

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