Table 3.
Common recycling processes and deterioration rates for selected polymers (adapted from Hamad et al., 2013; Hollstein and Wohlebe, 2015; La Mantia 1998).
| Types of emerging solutions |
Polymer type | Common separation efficiency and Impurities |
Recycling process | Most prominent secondary products | Relevant criteria for recycling |
|
|---|---|---|---|---|---|---|
| Most relevant properties | Recycling processes | |||||
| Drop-in solution | Bio-based PET | NIR sorting applicable, no extra separation needed |
Extrusion with virgin material, polyester fibres production |
Polyester fibres, non-food bottles | Decreasing melt viscosity | <3 Extrusion cycles |
| Bio-based PE | NIR sorting applicable, no extra separation needed |
Extrusion melting | Downcycling (non-opaque materials), refuse derived fuel | Deteriorated melt flow index (MFI) | <4 Extrusion cycles | |
| Novel polymer solution | PLA | Small amount blendable with PE or PET, extra separation or collection with organic waste |
a. Home and industrial composting or b. Screw extrusion or injection moulding |
Refuse derived fuel, thermal recycling, mineralization |
Decreasing intrinsic viscosity | <2 Extrusion cycles |
| Blends of novel polymers and fossil-based polymers | PLA-PMMA blend | Bulky waste/ scrap collection | Thermal treatment or pyrolysis |
Waste2Energy or MMA as recovered feedstock |
Mineral contents, heavy metal contents content of halogenated compounds |
Recovery efficiency of pyrolysis |
PET: polyethylene terephthalate; PMMA: polymethylmethacrylate; PE: polyethylene; PLA: polylactic acid; NIR: near-infrared; MMA: methylmethacrylate.