Rubber fluoro-elastomer

Sicka, R. W. Mitchell, G. B. "Phosphonitri1ic Fluoro-elastomer Coated Fabrics For Collapsible Fuel Storage Tanks", The Firestone Tire and Rubber Company, Akron,... 

Bhowmick and co-workers [168] investigated the bulk and surface modification of ethylene propylene diene monomer (EPDM) rubber and fluoro-elastomer by electron beam irradiation. The structure of the modified elastomers was analysed with the help of IR spectroscopy and XPS. The gel content, surface energy, friction coefficient and dynamic mechanical properties of bulk modified fluoro-elastomers and the surface-modified EPDMs were also measured. The resultant properties of the modified EPDM were correlated with the structural alterations. 

Some typical elastomers are natural rubber, which is gathered from trees, SBR rubber, which is used a lot in motorcar tires, neoprene, as in wet suits and oil seals, EPDM, a general purpose rubber, butyl, a heat-resistant rubber with the ability to keep the air in car tires, nitrile for oil seals, silicones for heat resistance, fluoro-elastomers for chemical resistance, and last but not least, polyurethanes, which cover a number of the above fields. Table 1.1 shows some of the advantages of castable polyurethanes over conventional rubbers. 

Property Butyl/halobutyl (isobutylene- isoprene copolymer) N atur al/Isoprene (cis-1,4-polyisoprene) Nitrile (butadiene- Sdicone Neoprene acrylonitrile (polydi-(polycbloroprene) copolymer) metbysiloxane) Fluoro- elastomers (fluoro- rubber) Uretbane (polyesterisocyanate) EPDM (etbylene Butadiene propylenediene (cis-polybuta-monomer) diene) ... 

A research group in Korea used a new method to incorporate fluoro-elastomer rubber (FR) in NR matrix. FR is the designation given to about 80% of fluoroelastomers with vinylidene fluoride (VDF), whieh provides... 

As mentioned previously, interest in fluorine-containing copolymers has been particularly concerned with the development of rubbers. Many copolymers have been investigated but the bulk of the commercial production of fluoro-elastomers is accounted for by vinylidene fluoride copolymers, of which those with hexafluoropropylene are the most important. 

Another fluorine containing polymer of rather more complex chemical structure is found in one of the inert synthetic rubbers called a fluoro-elastomer, which is mostly found in the form of seals and O rings. 

Currently-used elastomers include natural rubber, the identical synthetic cis-polyisoprene, butyl rubber, nitrile rubber, neoprene rubber, ethylene-propylene co-polymer rubber, fluoro rubber, urethane rubber and silicone rubber. 

As a result of its saturated polymer backbone, EPDM is more resistant to oxygen, ozone, UV and heat than the low-cost commodity polydiene rubbers, such as natural rubber (NR), polybutadiene rubber (BR) and styrene-butadiene rubber (SBR). Therefore, the main use of EPD(M) is in outdoor applications, such as automotive sealing systems, window seals and roof sheeting, and in under-the-hood applications, such as coolant hoses. The main drawback of EPDM is its poor resistance to swelling in apolar fluids such as oil, making it inferior to high-performance elastomers, such as fluoro, acrylate and silicone elastomers in that respect. Over the last decade thermoplastic vulcanisates, produced via dynamic vulcanisation of blends of polypropylene (PP) and EPDM, have been commercialised, combining thermoplastic processability with rubber elasticity [8, 9]. 

Solid-state 13C NMR has been used to identify elastomers in binary blends of chloroprene (CR) and NR, CR and CSM, NR and CSM, and SBR and acrylonitrile-butadiene rubber (NBR). The type of NBR can be determined by identifying the sequences of acrylonitrile and butadiene. The tertiary blend of NR/SBR/BR was also studied [49]. High-temperature 13C solid-state NMR identified ethylene-propylene diene terpolymer (EPDM) and fluoro and nitrile rubbers [50]. 

Silicone rubber offers a set of unique properties to the market, which cannot be obtained by other elastomers. The Si-0 backbone provides excellent thermal stability and, with no unsaturation in the backbone, outstanding ozone and oxidative stability. The very low glass transition temperature, combined with the absence of low-temperature crystallization, puts silicones among the materials of choice for low-temperature performance. The fluoro-substituted versions provide solvent, fuel, and oil resistance along with the above-mentioned stability advantages inherent with the silicone backbone. 

Vinylidenefluoride/hexa-fluoro propylene elastomer rubbers with fluoro and fluoroalkyl or fluoroalkoxy groups Gutta percha... 

M class elastomers contain only C atoms and no double bonds in their backbones this improves aging resistance. Examples ethylene-propylene rubber (EPDM), acrylate rubber (ACM), fluoro rubber (EKM)... 

When, furthermore, the resistance against the aforementioned media is taken into account only a few elastomer classes remain. Most suitable are the following HR (butyl rubber) and EPDM (ethylene propylene diene rubber) or more generally hydrocarbon-based rubbers with highly saturated polymer backbones for sufficient temperature resistance and chemical ineitness as well as FKM (fluoro rubber), which is especially suited for high-temperature applications. 

The best source of known samples of rubbers is to purchase labelled O rings, as one of these will last for quite a long time if carefully used in the burning tests. Natural rubber has quite a distinctive odour when burned everyone must know the smell of burning rubber, it is easily possible to distinguish between this and nitrile or neoprene for instance. Fluoro and silicone elastomers likewise have their own characteristic combustion properties. 

FKM Elastomer with saturated main chain and fluoro, perfluoroalkyl, or perfluoroalkoxy GU Fibers from diene rubbers (old German technical literature)... 

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