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.
The primary synthetic rubbers include nitrile, isoprene, styrene-butadiene, butyl, chloroprene, polysulfide, silicone, urethane and ethylene propylene diene terpolymer (ETP) or Ethylene Propylene Diene Monomer (EPDM).The synthetics rubbers are called indistinctly ETP or EPDM.EPT is a synthetic rubber known for its superior ability to cope with various climatic conditions, and its resistance to ozone, heat and coldness. It also performs well as an electric insulator and is known for its chemical resistance.he primary synthetic rubbers include nitrile, isoprene, styrene-butadiene, butyl, chloroprene, polysulfide, silicone, urethane and ethylene propylene diene terpolymer (ETP) or Ethylene Propylene Diene Monomer (EPDM). The synthetics rubbers are called indistinctly ETP or EPDM.