Acrylonitrile-butadiene rubber thermoplastic

The elastomeric sealing components of the metering valve are particularly critical. In those valves used with CFC propellants, the elastomeric seals have typically been formed from an acrylonitrile/butadiene rubber, which has been cured with sulfur. These rubber seals may not be fully compatible with HFA propellants hence, alternative elastomeric materials have been used. These materials include peroxide-cured acrylonitrile/ butadiene, ethylene-propylene diene monomer (EPDM), and chloroprene and thermoplastic elastomers (TPE). The elastomeric materials used to form the dynamic seals around the stem and the static gasket seal between the can and valve may differ based on the required properties of the rubber for the specific function of the seal. The most important characteristics of the elastomeric seals... 

Acrylic elastomer Acrylonitrile-butadiene rubber, hydrogenated Polyethylene, ultrahigh m.w. high-density Polynorbornene Polyurethane elastomer, thermoplastic Styrenated diphenylamine , Styrene-ethylene/butylene-styrene block copolymer seals, chemical-resistant Chlorotrifluoroethylene polymer seals, dynamic aerospace Polyfluoroalkoxyphosphazene seals, dynamic industrial Polyfluoroalkoxyphosphazene seals, dynamic military Polyfluoroalkoxyphosphazene seals, high performance Tetrafluoroethylene/perfluoromethylvinyl ether copolymer seals, oil... 

Germany, in the guise of I. G. Farben, had the foresight to realize the importance of this area, and they dominated the early research and development work. Their commercial successes ranged from rubber-like materials—the co-polymers poly(styrene-butadiene) and poly(acrylonitrile-butadiene)— to thermoplastics like poly(vinyl chloride) and polystyrene. 

The blending of natural rubber with thermoplastics, and other rubbers have been reported in the literature. Thus, blends of NR with (i) ultra-low density polyethylene, (ii) styrene-butadiene rubber (SBR), (iii) epoxidized natural rubber, (iv) acrylonitrile butadiene rubber," (v) chloroprene rubber" and (vi) dichlorocarbene modified styrene-butadiene rubber (DCSBR)" have been prepared, characterized and reported in the literature. 

The Swiss company, WW Fischer, offers PTFE (Teflon PTFE or Hostaflon), PBT (Celanex, Crastin, Ultradur or Valox) or PEEK (Victrex) insulator material options in its 405 series of cylindrical connectors according to the requirements of working temperature and other criteria. PEEK is an expensive polymer which tends to be employed when other materials fail to meet the specification requirements of the application. Other Fischer connector types use polyamide-imide (Torlon) or POM (Celcon, Delrin or Hostaform). Elastomeric seals used by Fischer in conjunction with their connectors are made from acrylonitrile-butadiene rubber (NBR N BUNA) or to MIL-P-25732, fluoroelastomer (FPM VITON), polychloroprene elastomer (CR Neoprene), ethylene-propylene diene elastomer (EPDM) and styrene-ethylene-butadiene-styrene thermoplastic elastomer (TPE-S or TPE-O) where each compound is followed by its trade name. Fischer s Swiss competitor, Lemo, manufactures a similar range of connectors including the Redel types which have a plastic body. 

Reactive blends of rubber and plastics are well known thermoplastic elastomers [132]. However, only a few blends with PBT are described. Cai and Isayev [113,114] reported the obtaining of new thermoplastic elastomers from blends of a copoly(ether-ester) (PBT- PTMO) and poly(acrylonitrile-butadiene) rubber (NBR) by the dynamic vulcanization process. These types of TPE show... 

Example 5-23) and of ABS-polymers (made from acrylonitrile, butadiene, and styrene), whereby grafting occurs in situ at the beginning of the polymerization process. The formed graft copolymers act in two ways As emulsifiers during the polymerization process and, secondly, in the solid end product as compatibilizer between the thermoplastic hard phase and the rubber-elastic dipersed phase (already in concentrations below 3%). 

Several flexible polymers, such as natural rubber (NR) synthetic rubber (SR) polyalkyl acrylates copolymers of acrylonitrile, butadiene, and styrene, (ABS) and polyvinyl alkyl ethers, have been used to improve the impact resistance of PS and PVC. PS and copolymers of ethylene and propylene have been used to increase the ductility of polyphenylene oxide (PPO) and nylon 66, respectively. The mechanical properties of several other engineering plastics have been improved by blending them with thermoplastics. 

RESINS (Acrylonitrile-Butadiene-Styrene). Commonly referred to as ABS resins, these materials are thermoplastic resins which are produced by grafting styrene and acrylonitrile onto a diene-rubber backbone. The usually preferred substrate is polybutadiene because of its low glass-transition temperature (approximately —80°C). Where ABS resin is prepared by suspension or mass polymerization methods, stereospedfic diene rubber made by solution polymerization is the preferred diene. Otherwise, the diene used is a high-gel or cross-linked latex made by a hot emulsion process. 

Order-disorder transitions and spinodals were computed for linear multi block copolymers with differing sequence distributions by Fredrickson et al. (1992). This type of copolymer includes polyurethanes, styrene-butadiene rubber, high impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene (ABS) block copolymers. Thus the theory is applicable to a broad range of industrial thermoplastic elastomers and polyurethanes. The parameter... 

Styrenic copolymers are materials capable of thermoplastic processing which, in addition to styrene (S), also contain at least one other monomer in the main polymer chain. Styrene-acrylonitrile (SAN) copolymers are the most important representative and basic building blocks of the entire class of products. By adding rubbers to SAN either ABS (acrylonitrile-butadiene-styrene) or ASA (acrylate-styrene-acrylonitrile) polymers are obtained depending on the type of rubber component employed. These two classes of products yield blends composed of ASA and polycarbonate (ASA -f PC) or ABS and polyamide (ABS -(- PA). 

Blends of butadiene-acrylonitrile copolymer rubber (nitrile rubber or NBR) and PVC are among the oldest known examples of commercial elastomer/ thermoplastic blends. The shortage of natural rubber during World War II stimulated research in the USA on the compounding and modification of synthetic polymers to produce rubber-like materials. An outcome of this research was the commercial introduction of NBR/PVC blends by B.F. Goodrich in 1947 under the trade name of Geon Polyblends [Pittenger and Cohan, 1947]. The blend showed improved ozone resistance and melt processability compared to the nitrile rubber (Table 15.12). 

The resulting polymer, on further heat treatment at elevated temperatures, is a source of graphite filaments. However, acrylonitrile copolymerized with other monomers finds extensive use in thermoplastic and elastomeric applications. Examples of such copolymers include styrene-acrylonitrile (SAN), acrylonitrile-butadiene-styrene terpolymer (ABS) and nitrile-butadiene rubber (NBR). 

Styrene serves as the monomer for the well-known polymer—polystyrene. It also serves as the source of many copolymers, that is polymers made from two monomers at varying compositions, such as SAN = styrene-acrylonitrile SBR = styrene-butadiene rubber (the major synthetic rubber) SBS = styrene-butadiene-styrene (a modem family of thermoplastic mbbers which are not cross-linked) and the well-known terpolymer ABS which is based on 3 monomers—acrylonitrile-butadiene-styrene. 

N nylon, PO polyolefin, elastomer, TPU thermoplastic urethane, GF glass fiber, NBR nitrile rubber, MAH maleic anhydride, EPR ethylene-propylene copolymer, l ionomer, M- mineral, ABS acrylonitrile-butadiene-styrene copolymer, PPE poly (phenylene ether), R reinforcement, PTFE poly(tetrafluoroethylene), CF° carbon fiber, PEBA poly(etherblockamide), S silicone, RIPP D reaction injection molding plastic, and ASA acrylate-styrene-acrylonitrile copolymer. 

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