What is Rubber Chemical Devulcanization?
Chemical devulcanization, applied since the 1960s, is nowadays among the most diffused. It
employs various organic and inorganic chemical compounds that selectively break carbon-
sulfur and/or sulfur-sulfur bonds. Generally, a supply of thermal and mechanical energy
accelerates the treatment. Most chemical devulcanization methods are batch processes, in
which ground waste rubber is mixed with chemical agents, at a controlled temperature and
pressure. Many types of chemical compounds can be used, such as sulfides, mercaptans,
amine-based compounds, inorganic solvents like propane thiol/piperidine,
triphenylphosphine (PPh3), trialkyl phosphites, lithium aluminum hydride, and methyl iodide,
organic solvents like alcohols and ketones, and ionic liquids (ILs). The drawback relates to
toxicity of chemicals. This problem could be partially mitigated by employing less toxic, more
environmentally friendly, non-sulfured agents.