Rubbers chlorobutyl

Chlorobutyl rubber is prepared by chlorination of butyl rubber (chlorine content is about 1 wt%). This is a substitution reaction produced at the allylic position, so little carbon-carbon double unsaturation is lost. Therefore, chlorobutyl rubber has enhanced reactivity of the carbon-carbon double bonds and supplies additional reactive sites for cross-linking. Furthermore, enhanced adhesion is obtained to polar substrates and it can be blended with other, more unsaturated elastomers. 

FIGURE 9.15 Typical force curves on (a) chlorobutyl rubber (CIIR) and (b) natural rubber (NR) samples showing much greater hysteresis and hence poorer resibence for the CIER sample. (From Huson, M.G. and Maxwell, J.M., Polym. Test., 25, 2, 2006.)... 

FIGURE 9.18 (continued) (b) Resilience measurements of elastomers. Samples of chlorobutyl rubber (CIIR), polybutadiene rubber (BR), and cross-linked recombinant resilin. (From Elvin, C.M., Carr, A.G., Huson, M.G., Maxwell, J.M., Pearson, R.D., Vuocolol, T., Liyou, N.E., Wong, D.C.C., Merritt, D.J., and Dixon, N.E., Nature, 437, 999, 2005.)... 

It is possible to cross-link polyisobutylene and poly(isobutylene-isoprene) and chlorobutyl rubber by means of certain additives however, the physical properties of the vulcanizates prepared by conventional curing methods cannot be attained. The most promising results were obtained with chlorobutyl compounds containing thioether polythiols as prorads. ... 

In flue gas desulphurization systems, equipment such as absorber towers, demister supports, gas outlets, recycle and process pipings, process tanks, and agitators are highly exposed to corrosive and abrasive environments. Chlorobutyl rubber of 60 Shore A... 

The blends of XNBR and chlorobutyl rubber (CIIR) and XNBR-epichlorohydrin rubber (ECO) act as adhesive for aluminium-aluminium bonding [171,172], In order to study the adhesion between CIIR-XNBR blend on aluminium foil, Bhattacharya and co-workers... 

Fig. 3. Plot of Young s storage modulus versus temperature in degrees Centigrade at 10 Hz for nitrile-epichlorohydrin blend and chlorobutyl rubber.

An HAF carbon black, N347, was selected for use as the primary filler. This was primarily because HAF blacks gave satisfactory adhesion of vulcanized chlorobutyl rubbers to metal, and good tensile and tear properties. 

Fig. 6. Plot of Young s storage modulus versus reduced frequency at 10 degrees Centigrade as a function of carbon black loading for chlorobutyl rubber. (Reproduced from Ref. 14. Copyright 1986 ACS). (PHR = parts per hundred of rubber).

The development of constrained-layer damping materials through the use of dynamic mechanical testing and mathematical modeling has been described. It has been shown how different types and loadings of fillers will affect the measured viscoelastic properties of chlorobutyl rubbers. It has then been shown how these changes will affect the damping performance of these materials in constrained layer structures. 

Fig. 33. Vulcanization kinetics and tensile properties of chlorinated HTI (CHTI, ) and comparison with chlorobutyl rubber (CIIR, ). Recipe as in Fig. 23 except, MBT = 1 T = 160 °C...

The choice of materials available for long-term drug contact is very limited—borosilicate glass, bromobutyl or chlorobutyl rubber closures, certain inert polymers such as polytetrafluoroethylene (PTFE), tetrafluor-oethylene (TFE), and derivatives thereof, and stainless steels. Since the Code of Federal Regulations mandates that it be possible to inspect the drug product after filling, steel cannot be used as the primary drug container. In addition, polycarbonates, which would be ideal materials from durability, scratch-resistance, and cost perspectives, have very poor moisture vapor and extractables profiles. 

Finally, materials commonly employed in the construction of respirators would include natural rubber, butyl rubber, chlorobutyl rubber, bromobutyl rubber, neoprene, and silicone. 

Facepiece materials must be chemically resistant and impermeable to agents ( chemically hard ) while being flexible (especially at the seals), comfortable, non-toxic to the skin, easily workable, inexpensive and have a long shelf-life. Eyepieces and visors must also be transparent. It is difficult to combine all of these features in one material in particular, flexible and chemically hard materials are typically difficult to work with and uncomfortable next to the skin. On the other hand, easily workable and comfortable materials tend to absorb agent (nerve agents are good solvents), which will then off-gas , e.g. in a collective protection system. In extreme cases, the agent can penetrate the material itself. Chemical hardness is of primary importance and most facepieces are made of chlorobutyl rubber. 

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