Rubber copolymer

A number of higher poly(vinyl ether)s, in particular the ethyl and butyl polymers, have found use as adhesives. When antioxidants are incorporated, pressure-sensitive adhesive tapes from poly(vinyl ethyl ether) are said to have twice the shelf life of similar tapes from natural rubber. Copolymers of vinyl isobutyl ether with methyl acrylate and ethyl acrylate (Acronal series) and with vinyl chloride have been commercially marketed. The first two products have been used as adhesives and impregnating agents for textile, paper and leather whilst the latter (Vinoflex MP 400) has found use in surface coatings. 

Isocyanates can be added to solvent-borne CR adhesive solutions as a two-part adhesive system. This two-part adhesive system is less effective with rubber substrates containing high styrene resin and for butadiene-styrene block (thermoplastic rubber) copolymers. To improve the specific adhesion to those materials, addition of a poly-alpha-methylstyrene resin to solvent-borne CR adhesives is quite effective [76]. An alternative technique is to graft a methacrylate monomer into the polychloroprene [2]. 

Nitrile rubbers, copolymers of butadiene and acrylonitrile, are used for resistance to swelling by mineral oils and fuels enhanced by formulations with a high acrylonitrile/butadiene ratio. They have poor resilience and low-temperature properties. However, these rubbers should not be used with ketones, phenols or aromatic hydrocarbons [66-69]. 

Fluorinated rubbers, copolymers of hexafluoropropylene and vinylidene-fluorides, have excellent resistance to oils, fuels and lubricants at temperatures up to 200°C. They have better resistance to aliphatic, aromatic and chlorinated hydrocarbons and most mineral acids than other rubbers, but their high cost restricts their engineering applications. Cheremisinoff et al. [54] provide extensive physical and mechanical properties data on engineering plastics. A glossary of terms concerned with fabrication and properties of plastics is given in the last section of this chapter. 

FIGURE 1.12 Master curve of tear energy Gc versus rate R of tear propagation at Tg for three cross-linked elastomers polybutadiene (BR, Tg — —96°C) ethylene-propylene copolymer (EPR, Tg — —60°C) a high-styrene-styrene-butadiene rubber copolymer (HS-SBR, Tg — —30°C). (From Gent, A.N. and Lai, S.-M., J. Polymer Sci., Part B Polymer Phys., 32, 1543, 1994. With permission.)... 

The sol fractions occurring in a series of cross-linked Tutyl rubber copolymers consisting of a small proportion of isoprene with isobutylene units have been found to vary with y in accordance with Eq. (50). The unfortunately large experimental inaccuracy precluded a precise test, however. 

Acrylonitrile-butadiene-styrene (ABS) copolymers Ethylene-methacrylic acid copolymers Styrene-butadiene rubber copolymers (SBR)... 

Nitrile rubber - Copolymers of acrylonitrile and butadiene. Same as NBR or Buna-N. 

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

Minutes to PVC, % Product, % 100 Grams of Starting Rubber 100 Grams of Starting Rubber Copolymer, %... 

ACRN is used to make acrylic fibers, acrylonitrile-butadiene-styrene (ABS), and styrene-acrylonitrile (SAN). Worldwide acrylic fiber accounts for over half of total demand while ABS and SAN consume about 30% of output. Smaller applications include nitrile rubber copolymers (4%), adiponitrile (ADN) and acrylamide. Acrylic fibers are used in carpets and clothing while ABS and SAN resins are used in pipes and fittings, automobiles, furniture, and packaging276. In the United States the ACRN uses are distributed differently 38% is used in ADN, 22% in ABS and SAN, 17% in acrylic fibers, 11% in acrylamide, 3% in nitrile elastomers, and 9% in miscellaneous, which includes polymers, polyols, barrier resins and carbon fibers277. 

The Norplant contraceptive implant is a set of six flexible, closed capsules made of a dimethylsiloxane/ methylvinylsiloxane copolymer containing levonorgestrel. The silicone rubber copolymer serves as rate-... 

The molecular weights estimated are 4.5 x 105 for ECH polymer and 1.4 x 106 for ECH/EO copolymers. Homopolymer ECH (I) and copolymer ECH/EO (2) are solvent-resistant rubbers. Copolymers with AGE are S-vulcanizable rubbers. 

There are a number of grades of fluorocarbon rubber (copolymers, terpolymers and tetrapolymers) and they are mainly used in applications where the temperatures would degrade ethylene-propylene rubber products. They are able to withstand prolonged use at temperatures up to 200 °C. Typical conditions are high temperature (<150 °C) gaskets under flow or static conditions, in contact with aqueous or fatty foods (including oils). 

Test polymers for visualization studies were polyurethane (Pellethane, 2363-80A, Upjohn), filler-free polydimethylsiloxane (Sil-Med Corporation), two forms of Teflon, sintered (TFE, DuPont) and Fluorofilm (Dilectrix Corporation), and polyurethane-silicone rubber copolymer (AVCOthane 51, AVCO). Samples of 1 cm2 or, for shear studies, 5 X 20 X 0.5-cm sheets, were washed in ionic detergent solution (Alconox) at 60°C for 1 h, rinsed in deionized water, and refluxed in absolute ethanol for 1 h. Materials were dried and stored in a desiccator until use. 

Polyisobutylene (Butyl Rubber, Copolymer with 0.5-2% Isoprene) (HR) Chloro-Sulfonated Polyethylene (CSM) Ethylene-Propylene Random Copolymer, 50% Ethylene (EPM) Ethylene-Propylene Random Terpolymer 50% Ethylene (EPDM) Poly(Ethyl Acrylate), Usually a Copolymer (ACM) Vinylidene-Fluoride-Chlorotrifluoro Ethylene Random Copolymer (FKM) Vinylidene— Fluoride— Hexafluoropropylene Random Copolymer (FKM)... 

Jung et al. have developed a synthetic elastomer composed of acrylonitrile butadiene rubber copolymer [211, 212]. The properties of the copolymer can be tuned by changing its composition. Reported data for dielectric constant, elastic modulus, and strain relaxation are promising (see Table 1.2). The synthetic elastomer provides some improvement over VHB and some silicone hlms under certain conditions however, the tests were limited to low prestrain (60% radial), where the performance of VHB hlms is poor. 

This degradation reaction, supplemented by various subsequent oxidation steps, has found renewed interest in the form of the introduction of photodegrad-able plastics as part of the campaign to reduce plastic litter from throwaway packaging. Although as yet there has been no demand for photodegradable mb-bers, the incorporation of a small percentage of a vinyl ketone into a rubber copolymer or homopolymer would open the way to a useful synthesis of block copolymers. 

MAJOR APPLICATIONS Acrylonitrile copolymers are used extensively in textile fiber manufacture and in nitrile rubber. Copolymers are used in gaskets, grommets, hoses, printing roll surfaces, diaphragms, and in plumbing accessories. They also are used in adhesive and coating applications. 

Ethylene Acrylic Rubber Copolymers of ethylene and acrylic esters. Has good toughness, low temperature properties, and resistance to heat, oil, and water. Used in auto and heavy equipment parts. 

Studies of the dependence of EEC properties obtained as above on the formation method showed that the precipitated finely dispersed rubber that is not bonded to the epoxy matrix does not endow it with high mechanical characteristics. When reactive oligomers are applied with high-temperature cure, there is a sharp enhancement of the modifying efficiency, accounting for the more intensive separation of the phases in the system and for the increase of the yield of the epoxy rubber copolymer. Thus, the structure and properties of epoxy resins modified by rubbers are mainly determined by the mode of system curing, but the quantitative relationships between curing mode and final properties have not been sufficiently studied. 

High molecular weight homopolymers of 1,3-butadiene formed by a free-radical mechanism lack the type of elastomeric properties that are needed from commercial rubbers. Copolymers of butadiene, however, with styrene or acrylonitrile are more useful and are prepared on a large scale. This is discussed in another section. 

Uses Mfg. of syn. and butyl rubbers copolymer for syn. rubbers monomer for prod, of polyisoprene chem. intermediate resins cosmetics ingred. 

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