acrylonitrile antiozonant applied spectroscopy brittleness butyl rubber carboxylic acid compressor copolymer corona discharge corrosion degree of polymerization diaphragm seal esem elastomer electrostatic discharge energy-dispersive x-ray spectroscopy forensic chemistry forensic engineering forensic materials engineering forensic polymer engineering fuel line hypalon ketone nbr natural rubber neoprene nitrile rubber ozone ozonide ozonolysis polybutadiene polymer degradation repeat unit silicone rubber static electricity stress concentration stress corrosion cracking styrene-butadiene sunlight tensile strength tire viton vulcanization