Acrylonitrile butadiene rubber (NBR) has excellent oil resistance.
However, shows no self-reinforcing effect, as there is no
crystallinity, but when used in combination with reinforcing fillers,
vulcanizates with excellent mechanical properties can be obtained
from NBR [1]. Vulcanization occurs by a chemical agent, such as
sulfur or peroxide. Alternatively, high-energy radiation, such as
electron beam or gamma radiation can be used to vulcanize rubbers
[2].
The use of organic peroxide as a cross-linking agent through a
free radical process is also largely developed. The vulcanization
rate is controlled essentially by the decomposition of the peroxide
at a given temperature [3]. Compared with sulfur vulcanization,
crosslinking by peroxides is a relatively simple process, with physical
properties such as high modulus, low compression set and heat
ageing properties superior to sulfur cure systems. On the other
hand, the peroxide crosslinking has many disadvantages, such as
low tensile and tear strength, and flex resistance, which have restricted
their use in diene rubbers. Many unsaturated rubbers, such
as natural rubber (NR), styrene–butadiene rubber (SBR), butadiene
rubber (BR), and acrylonitrile butadiene rubber (NBR), contain a
varying degree of unsaturation in the polymer backbone or in pendant
positions. Peroxide radical could potentially react by addition
to a double bond or by abstraction of an allylic hydrogen, and both
mechanisms occur concurrently in the vulcanization of unsaturated
elastomers [4].