Homogeneous nitrile rubber

Ester plasticizers are used in highly polar elastomers, such as neoprene and nitrile rubber, to improve low or high temperature performance or impart particular oil or solvent resistance to a compoimd. From 5 to 40 phr are commonly used (see PLASTICIZERS). Resins and tars are added to impart tack, soften the compoimd, improve flow, and in some cases improve filler dispersion, as is the case with organic resins in mineral-filled SBR. Resinous substances are also used as processing agents for homogenizing elastomer blends. 

Because of the regular structure both the raw polymer and the vulcanizates of these rubbers are claimed to be capable of crystallization (this implying some tactic homogeneity of the acrylonitrile in addition) so that the tensile strength of both cured and uncured stocks is higher than for conventional nitrile rubbers. Resistance to cut-growth and to creep tear are also said to be superior. Properties less dependent on structural regularity, such as oil resistance and low temperature properties are similar to those of free-radically produced random copolymers. 

The second major effect of increasing the acrylonitrile content of nitrile rubber is an increase in the glass transition temperature. Glass transition temperatures for nitrile rubbers of homogeneous compositions may vary from approximately -60 to -10° C as the acrylonitrile content is increased from 15 to 50%, respectively. However, it is also well known that... 

For the homogeneous, nonbonded materials evaluated in these studies (butyl rubber, neoprene latex, nitrile latex, polyethylene, polyvinyl alcohol), surgical rubber latex, and Viton elastomer), only the perlyVinyl alcohol) did not correlate well in this relationship. As has been shown in Fig. 6, most likely the polyethylene... 

Wang H, Yang L, Rempel GL. Homogeneous hydrogenation art of nitrile butadiene rubber a review. Polym Rev. 2013 53 192-239. 

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