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 is the most commonly used rubber material. This is due to Nitrile's compatibility with most environments as well as it's relative cost compared to other rubber materials. Mykinâs RN00170, Nitrile (BUNA-N) 70 durometer, is a general purpose copolymer of butadiene and acrylonitrile. This compound has a relatively high acrylo content, making it exceptionally resistant to petroleum base oils and hydrocarbon fuels over a temperature range of -40Â°F to +250Â°F.