what is the material of Buna-N ?

Buna-N rubber, BUNA (slang) is the mean of butadiene, BUNA it originated during World War II, first synthesized by the German catalyst with sodium, hence the name Buna. BUNA is foreign Bunaa grade, now Russia's use of the more it has two structures is BUNA_S (a considerable domestic butadiene rubber) BUNA_N (equivalent to the NBR).

BUNA_N in the N Nitrile abbreviation meaning of acrylonitrile, which is the abbreviation of the nitrile rubber. So BUNA-N nitrile rubber, Buna abbreviation is BUNA, which is separate BU and NA BU is butadiene, NA is the sodium.
Butadiene rubber, Buna as the monomer to polybutadiene, the former is made ​​by bulk polymerization, the reason for naming Buna metal sodium as initiator, butadiene gas or liquid phase polymerization the system. Butadiene rubber is made ​​by emulsion polymerization.
The Buna main characteristics of 1,2 - higher content of chain branching density, molecular weight distribution of a wide, now used rarely, characterized by high dynamic characteristics (anti repeatedly pull strong almost) and a low fever, with butadiene rubber polymerization