MONOMER RECOVERY BY PYROLYSIS OF POLY(METHYL METHACRYLATE) (PMMA)

There are many processes to recover the valuable methylmethacrylate (MMA) of PMMA waste. The yield of MMA using melting vessels or heated screw feeders is not sufficient and lies between 50 and 80 wt%. In a indirectly heated fluidized bed process with a temperature of 450-degrees-C more than 97 wt% of the PMMA could be recovered as monomer. The yield depends on the pyrolysis temperature. At 590-degrees-C the gas fraction increases drastically. The main components of the gas are methane, ethene, propene, carbon monoxide and carbon dioxide. The main component in the liquid beside the MMA is methyl acrylate. It is possible to polymerize the liquid to new PMMA after distillation without any other purification. Even filled and coloured PMMA materials like rear lights of cars could be polymerized to a polymerization grade liquid.