Elastomer with acrylic copolymer

II. Blends of Resins with Acrylic Copolymer 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). 

Among the different pressure sensitive adhesives, acrylates are unique because they are one of the few materials that can be synthesized to be inherently tacky. Indeed, polyvinylethers, some amorphous polyolefins, and some ethylene-vinyl acetate copolymers are the only other polymers that share this unique property. Because of the access to a wide range of commercial monomers, their relatively low cost, and their ease of polymerization, acrylates have become the dominant single component pressure sensitive adhesive materials used in the industry. Other PSAs, such as those based on natural rubber or synthetic block copolymers with rubbery midblock require compounding of the elastomer with low molecular weight additives such as tackifiers, oils, and/or plasticizers. The absence of these low molecular weight additives can have some desirable advantages, such as ... 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

Aqueous systems have been studied by a very large number of investigators. Economy, safety, convenience and quality of product have combined to make this the method of choice for commercial production of copolymers. The industrial importance of such end products as elastomers and acrylic fibers has been a special incentive to related fundamental studies. Furthermore, the relatively high solubility of acrylonitrile monomer in water coupled with insolubility of the polymer make it a convenient test monomer for studies of initiation by redox systems (6, 25, 102). Large numbers of homogeneous chemical initiators and some heterogeneous initiators have been studied as well as initiation by photochemical means, by ultrasonics and by ionizing radiation. It will not be possible here to review the enormous world literature. Several publications (/, 92, 117) refer in some detail to the older papers, and we shall restrict our comments to recent interpretations that have received support from several quarters. 

Lundgren, A., Hjertberg, T., and Sultan, B.-A. 2007. Influence of the structure of acrylate groups on the flame retardant behavior of ethylene acrylate copolymers modified with chalk and silicone elastomer. J. Fire Sci. 25 287-319. 

Hermansson et al. carried out extensive investigations on the fire-retardant behavior of ethylene-acrylate copolymer modified with chalk and silicone elastomer.30 32 They have shown that incorporation of a silicone elastomer (at 5wt.%) and chalk filler (at 30wt.%) can greatly improve the flame-retardant properties of ethylene butyl acrylate formulations. The results show that, compared to the pure polymer, an increase in the LOI from 18 to 30, and a decrease in the peak heat release rate (PHRR) from 1300 to 330kW/m2 were observed. 

PP and PC are immiscible, thus excepting the exploratory use as a plastic paper, only the two ends of the concentration range have been explored, viz. addition of 5 wt% PP to PC (to improve processability of PC) [Dobkowski, 1980], or addition of <10 wt% of PC (to improve PP processability, enhance crystallinity and crystallization temperature, the appearance, modulus, and impact strength) [Liang and Williams, 1991]. For concentrations >10 wt% compatibilization is necessary. This is accomplished using ethylene-acrylic copolymer, cellulosics, PA, PVAc, or TPU [Goldblum, 1963, 1964] an acrylic elastomer, acrylic elastomer with PP-MA and either butyl mbber, or isobutene-isoprene mbber [Teijin Chem., 1982, 1983] SBR and EEA [Liu, 1984] MBS [Overton and Liu, 1984] or EVAc [Giles and Hirt, 1986],... 

Chrome plated molds are recommended when injecting elastomer modified styrene-acrylic copolymer. Runners, gates and spmes should be smooth to minimize polymer turbulence during injection. Good mold temperature is needed for optimum clarity and surface gloss. Contamination with other materials will cause streaking and haze. 

Acrylate copolymers produced by emulrion polymerization are being used as elastomers which, after vulcanization, have a combination of heat resistance and oil resistance useful in specialty applications such as gai ts for automatic transmissions in automotive engines. Two t3q>es of copolymers are being used. In one, ethyl acrylate is copolymerized with about 5 per cent of a chloro-containing monomer such as chloroethyl vinyl ether in the other, either ethyl acrylate or butyl acrylate is copolymerized with about 5-15 per cent of acrylonitrile., ... 

Acrylic copolymers (i.e., core-shell impact modifiers with a shell of PMMA and a core of butyl acrylate elastomer) have been developed mainly for impact modification of PVC for outdoor applications. Butadiene-styrene copolymers are used exclusively for PVC, PC or styrene-acrylonitrile (SAN). Thermoplastic elastomers in the form of styrenic copolymers, e.g., SBS, are used preferably for styrenics and PA. Polyolefins, like EVA, are used for impact modification of technical polymers. 

Hu, W, Zhang, S.N., Niu, X., Liu, C., Pei, Q., 2014. An aluminum nanoparticle-acrylate copolymer nanocomposite as a dielectric elastomer with a high dielectric constant. J. Mater. Chem. C 2,1658. 

The above illustrated crosslinking reactions of homopolymers, however, form elastomers with poor aging properties. Commercial acrylic rubbers are therefore copolymers of ethyl or butyl acrylate with small quantities of comonomers that carry special functional groups for crosslinking. Such comonomers are 2-chloroethylvinyl ether or vinyl chloroacetate, used in small quantities (about 5%). These copolymers crosslink through reactions with polyamines. 

BM-400B is a dispersion system of SBR fine particles in water. These particles are random copolymer molecnles, i.e., styrene and butadiene, containing some other minor elements such as acrylic ester and organic acids. The copolymer is an elastomer with a glass transition temperature of -5°C. Its chemical formula is. 

This is accomplished using ethylene-acrylic copolymer, cellulosics, PA, PVAc, or TPU (Goldblum 1963, 1964) an acrylic elastomer, acrylic elastomer with PP-MA, and either butyl rubber or isobutene-isoprene rubber (Teijin Chem. 1982,1983) SBR and EEA (Liu 1984) MBS (Overton and Liu 1984) or EVAc (GUes and Hirt 1986). 

Ethylene-methyl acrylate copolymer (EA, E/EA) n. An elastomer vulcanizable with peroxides or diamines. It resists attack by oils and temperatures to 175°C. 

The new elastomers are particularly relevant to the automotive industry because they offer better properties - particularly heat, oil and fuel resistance - than the established materials such as natural and synthetic rubber and plasticized PVC. Among the most important types are PUR elastomers, PBT block copolymers, EPDM olefinic terpolymers and ethylene-acrylic elastomers. Typical applications are the traditional rubbery ones of gaskets, seals, gaiters and cable covers, but set in the aggressive underbonnet environment of today s performance vehicles. Beyond this, however, there are examples where these materials are sufficiently versatile to have been selected, sometimes with reinforcement, as engineering components in their own right. 

Pressure-sensitive adhesives form physical bonds with other materials upon brief contact and with light pressure. Examples include self-stick stamps, packaging tape, double-sided tapes, paper labels, and the ubiquitous Post-iE notes. Bond formation results from the polymeric material being able to flow under light pressure, thereby establishing good contact area with the substrate. The debonding step involves deformation of the polymeric material under stress (see Section 12.8.3), followed by separation from the substrate. The adhesives most often involve triblock copolymers such as poly(styrene-h/ock-isoprene-h/ock-styrene) or poly(styrene-Wodc-butadiene-h/ock-styrene), SBR elastomers, natural rubber, or acrylic copolymers (92). 

Aromatic Cg resins have good compatibility with SBR and EVAc elastomers, and some of them to acrylate copolymers. They have limited compatibility with natural rubber. For more details, see [211, pp. 527-544]. 

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