HYDROGENATED NBR

Y. Saito, A. Eujino, and A. Ikeda, High Strength E/astomers of Hydrogenated NBR Containing Einc Oxide and Methacry/ic Acid, Society of Automotive Engineers (SAE) Technical Paper Series, No. 890359, Detroit, Mich., Eeb. 27—Mar. 3, 1989. 

Guo et al. [70,71,73] recently attempted to hydrogenate NBR in emulsion form using Ru-PCy complexes. However, successful hydrogenation can only be obtained when the emulsion is dissolved in a ketone solvent (2-butanone). A variety of Ru-phosphine complexes have been studied. Crosslinking of the polymer could not be avoided during the reaction. The use of carboxylic acids or first row transition metal salts as additives minimized the gel formation. The reactions under these conditions require a very high catalyst concentration for a desirable rate of hydrogenation. 

Figure 4 Stress-strain curves of hydrogenated NBR containing 40 mol% ACN with different degree of hydrogenation. Source Ref. 11.

The efficiency of Crabtree s catalyst as a catalyst for small molecule hydrogenation has been known for many years. Unlike many homogeneous hydrogenation catalysts, Crabtree s catalyst is able to reduce hindered olefins at favourable rates.7 It has never been reported as a catalyst for the hydrogenation of rubber except for its use in the hydrogenation of bulk PBD.8 This paper describes the first use of Crabtree s catalyst in the hydrogenation NBR. Kinetic data are presented and analyzed to understand the underlying chemistry. 

Spectra of solution cast films of the hydrogenated NBR were recorded on a Nicolet 520 FT-IR spectrophotometer. The final degree of olefin conversion was confirmed by infrared analysis.9... 

Figure 4.1 Hydrogenation of NBR (34% acrylonitrile (ACN)) and hydrogenated NBR with 22.7, 11.0 and 0.6% mol unhydrogenated butadiene units...

Hydrogenated NBR (HNBR) is produced by first making an emulsion-polymerized NBR using standard techniques. It then must be dissolved in a solvent and hydrogenated using a noble metal catalyst at a precise temperature and pressure.60 Almost all the butadiene units become saturated to produce an ethylene-butadiene-acrylonitrile terpolymer. 

Aromatic PA (50)/ hydrogenated NBR (50)/ carboxy-terminated NBR (0-5) Miniature mixer at 250 °C/ morphology/ellipsometry/LlOl (0.9 phr) added for vulcanization of mbber phase/effects of mixing protocol/other carboxylated mbbers also used Bhowmick et al. 1993... 

NBR (75-25) or hydrogenated NBR/PVC (25-75) Internal mixer at 180 °C/rheometry/DMTA/ DSC/FTIR/solvent swelling Manoj et al. 1993a, b... 

Likozar et al. [148] obtained NBR/hydrogenated NBR mixed with MWCNTs using a melt compounding method, cured with peroxide, and further mixed with a two-roll mill. The resulted composites showed improved hardness, elastic modulus, tensile strength, elongation at break, and tear strength compared with noncured... 

Leone and Oliver [42] have discussed the applications of fluoroelastomers, nitrile rubber (NBR) and hydrogenated NBR in seals for automotive air-intake manifolds. They review the properties required for such seals including mechanical and low temperature properties, heat and fuel resistance, and design requirements for the seals used in conjunction with the engineering plastics components in this application. 

Pyrograms of NBR samples at 550 °C before and after hydrogenation (a) N-37(0), (b) N-37(440), and (c) N-37(98). Table 5.9 summarises the characteristic thermal degradation products observed on the pyrograms of NBR and hydrogenated NBR. Mass spectral data of the characteristic degradation products enabled many of them to be identified. 

Table 5.9 Characteristic degradation products from hydrogenated NBR ...

Figure 1.11 Relationship between observed 1 - [(Aj q/A oI AA q/A oIo] and degree of hydrogenation for hydrogenated NBR. Reproduced with permission from A. Kondo, H. Ohtani, Y. Kosugi, S. Tsuge, Y. Kubo, N. Asada, H. Inaki and A. Yoshioka, Macromolecules, 1988,21, 2918. 1988, American Chemical...

The results are reported of a study of the effects of gaseous oil, gaseous sour oil, oily gas and dry gas at different temperatures and pressures on several elastomers. These elastomers were CR, NBR, hydrogenated NBR, FKM and EPDM. 13 refs. 

Factors involved in failure mechanisms in elastomers (particularly hydrogenated NBR) subjected to gas exposures at high pressures and at various temps, are discussed. The prediction of the behaviour of rubbers under gas service is considered. 

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