Poly(methyl methacrylate) (PMMA) is currently produced at 3.9 million metric tons per year, being involved in different sectors, due to its high transparency, lightness and barrier properties that make this material particularly suitable for optical and electronic applications. However, it is estimated that nowadays only 10% of this production is recycled. Landfilling and incineration are still the dominant fates for waste PMMA. Since its market is expected to expand in the coming 7 years at a compound annual growth rate of 3.4%, this poses urgent concerns about the disposal of end-of-life PMMA. In this chapter, the PMMA market trends are first introduced to better define the boundaries of the topic. Then, the available technologies for PMMA recycling are discussed. Given the possibility of quantitatively depolymerize this polymer back to methyl methacrylate, the thermal decomposition is by far the most convenient and explored recycling route. The main focus is then on this process. Even though the knowledge on the reaction mechanism is still limited, the fundamentals accepted by the scientific community are presented. Then, the discussion is moved to the reactor configurations developed over the years for the thermolysis of PMMA, extensively referring to examples available in the patent literature. From this analysis, fluidized bed reactors and reactive extruders result the most appealing solutions in terms of environmental footprint and efficiency. However, additional research effort is required to properly design a process capable of treating not only high-quality feedstocks, but also end-of-life PMMA, possibly containing additives and comonomers.
Poly(methyl methacrylate): Market trends and recycling
Sponchioni, Mattia;
2022-01-01
Abstract
Poly(methyl methacrylate) (PMMA) is currently produced at 3.9 million metric tons per year, being involved in different sectors, due to its high transparency, lightness and barrier properties that make this material particularly suitable for optical and electronic applications. However, it is estimated that nowadays only 10% of this production is recycled. Landfilling and incineration are still the dominant fates for waste PMMA. Since its market is expected to expand in the coming 7 years at a compound annual growth rate of 3.4%, this poses urgent concerns about the disposal of end-of-life PMMA. In this chapter, the PMMA market trends are first introduced to better define the boundaries of the topic. Then, the available technologies for PMMA recycling are discussed. Given the possibility of quantitatively depolymerize this polymer back to methyl methacrylate, the thermal decomposition is by far the most convenient and explored recycling route. The main focus is then on this process. Even though the knowledge on the reaction mechanism is still limited, the fundamentals accepted by the scientific community are presented. Then, the discussion is moved to the reactor configurations developed over the years for the thermolysis of PMMA, extensively referring to examples available in the patent literature. From this analysis, fluidized bed reactors and reactive extruders result the most appealing solutions in terms of environmental footprint and efficiency. However, additional research effort is required to properly design a process capable of treating not only high-quality feedstocks, but also end-of-life PMMA, possibly containing additives and comonomers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
