Polybutadiene-acrylonitrile network

Epoxy structural adhesives which employ carboxylic polybutadiene/acrylonitrile solid and liquid (CTBN) elastomers as modifiers have increased in number and proliferated in use since their introduction in the mid- 60 s. Such adhesive systems are now used in aircraft, electronics, automotive and industrial bonding operations. In the mid- 70 s, amine-reactive versions of the liquid polymers (ATBN) were issued, thereby offering another way to introduce rubber modification into a cured epoxy network. References are cited which provide detailed discussions of nitrile rubber, carboxylic nitrile rubber and both carboxyl- and amine-terminated nitrile liquid polymers (1-4). ... 

Curatives are introduced into compounds to crosslink polymer chains. The most important curative is sulfur which produces (polymer)-S -(polymer) crosslinks. This primarily involves unsaturated elastomers based on isoprene and butadiene such as natural rubber, polybutadiene, and its copolymers with styrene and acrylonitrile (see Section 1.3). After crosslinking, the polymer networks show increased retractive force and reduced creep. The cured rubber becomes insoluble and it cannot be processed in the molten state. The concentration of curatives and their reactivity affect the degree of crosshnking. 

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