In 2012, mintage numbers were reduced by over 90%, in line with a similar reduction for the Presidential Dollars, due to large stockpiles of unused dollar coins.he coin was first suggested as a replacement for the Susan B. Anthony dollar, which proved useful for vending machine operators and mass transit systems despite being unpopular with the public.
Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as PIB or polyisobutene, (C 4 H 8) n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based.
Nitrile rubber. Nitrile rubber, also known as Buna-N, Perbunan, or NBR, is a synthetic rubber copolymer of acrylonitrile and butadiene.Trade names include Nipol, Krynac and Europrene. Nitrile butadiene rubber is a family of unsaturated copolymers of 2-propenenitrile and various butadiene monomers.t is used in the nuclear industry to make protective gloves. NBRâs ability to withstand a range of temperatures from -40 Â°C to +108 Â°C makes it an ideal material for aeronautical applications. Nitrile butadiene is also used to create moulded goods, footwear, adhesives, sealants, sponges, expanded foams, and floor mats.