polymers or plastics - does it matter for recycling? · source: sandra krautwaschl, plastik freie...
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Polymers or Plastics - Does it matter for recycling?
Marie K. Eriksen, Jesper D. Christiansen, Thomas F. Astrup, Anders E. Daugaard
Environmental Engineering Chemical and Biochemical EngineeringTechnical University of Denmark
Polymers2 DTU Chemical Engineering, Technical University of Denmark
Plastics – Imagine life without!
Source: Sandra Krautwaschl, Plastik Freie Zone
Polymers3 DTU Chemical Engineering, Technical University of Denmark
The oil age world production 1859-2050
Source: http://scimaps.org/mapdetail/the_oil_age_world_oi_73
Polymers4 DTU Chemical Engineering, Technical University of Denmark
Current production of plastics
Source:Plastics Europe and Nova-Institute
Polymers5 DTU Chemical Engineering, Technical University of Denmark
Type of plastic is important for its recyclingpotential
• Plastics – PE, PP, PET etc. • Fibers, Rubbers (elastomers), Coatings & Adhesives, Composites
• Formulation– Additives such as processing aids, antistatic additives– Stabilizers (e.g. hindered amines)/Absorbers (e.g.
benzophenones)/Antioxidants (e.g. steric hindered phenolic comp.) – Fillers (composites, absorbers e.g. carbon black, limestone etc.)– Colorants/pigments– Flame retardants etc.– Trace materials from the production of the polymers (eg. phthalates
from catalysts in polyolefin production)
Polymer
Composition of a plastic
ReinforcingFillers (particles)
0wt% 100wt%50wt%25wt% 75wt%
Polymers and recycling6 DTU Chemical Engineering, Technical University of Denmark
But what about the polymer?• Base polymer material
– Different composition – but same name, e.g. different types of PP– Metallocene vs. ZN polymerized materials– Branching, MW– Miscibility?
• If source is known – recycling easier• What if source is unknown? (Household plastics)
• There are many sources of some polymers, others are only produced for more specific applications
– PP or PE used in a variety of applications and formulations– PET produced for specific applications => easier recycling– Condensation polymers can be ”repolymerized”/upgraded– Addition polymers, if MW is reduced cannot as easily be increased
Polymers7 DTU Chemical Engineering, Technical University of Denmark
End-of-Life challenges on the way to a sustainable solution• Polymers in general (Biobased polymers/petrochemical based polymers)
– Direct recycling or downcycled?– Industrial waste– Houshold waste - complex combinations of polymers
• Biodegradable polymers– Composting (e.g. PLA) is it compatible?– Recycling – PLA processing is difficult, reuse even more so– Do we even want most polymer materials to degrade?
• What about thermoset materials? – Unsaturated polyesters/Epoxies/composites– Biodegradable materials
Polymers and recycling8 DTU Chemical Engineering, Technical University of Denmark
Recycling of Plastics – Industrial Waste
• Industrial waste– Directly during production, in-line shredding – Failed production etc.
• Advantages– Source or producer is known– Compounder is known– Exact composition and type of polymer is known– Intentionally added additives are known– At least the type and quality and limitations of use is known
• Requirement for direct recycling– Well described composition– Thermoplastic material
Polymers and recycling9 DTU Chemical Engineering, Technical University of Denmark
Recycling of Plastics – Household Waste
• Highly mixed fractions– Mixture of materials, Crosslinked plastics, semicrystalline plastics,
amorphous materials
• Sorting -Separation is possible, but– MW, processing?– Processing of mixed fractions– Compatibilizers e.g. copolymers
• Additives– Generally unknown– Pigments, stabilizers, etc. – After use some of these additives are degraded – long term effects?– Non intentionally added substances (NIAS)
Polymers and recycling10 DTU Chemical Engineering, Technical University of Denmark
Eriksen, M.K. et al. 2018, Waste Management, DOI: 10.1016/j.wasman.2018.08.007.
Polymers11 DTU Chemical Engineering, Technical University of Denmark
Polymers applied in products
Source: PlasticsEurope Market Research Group (PEMRG) and Conversio Market & Strategy GmbH
Polymers12 DTU Chemical Engineering, Technical University of Denmark
Samples and sample preparation• From characterisation of 3,400 kg source-separated
plastic waste from the Municipality of Copenhagen, a detailed composition of the rigid part of the plastic wasobtained.
• From this composition is was found that some products represent a considrable share of the rigid plastic waste(see the following slides)
• Samples were shredded and washed
• Labels and lids?
• What would happen if we generated a differentdistribution of waste?
Eriksen, M.K., Christiansen, J.D., Daugaard, A.E., Astrup, T.F., 2018
PET
13
Bottles for beverages
Trays for fruit andvegetables
Trays for mixed food-related purposes
PE
14
Bottles for soap-related purposes
PP
15
Tubs for dairy products
Meat trays
Trays for mixed food-relatedpurposes
Polymers16 DTU Chemical Engineering, Technical University of Denmark
Sample preparation
• Testing of prepared plastics– Composition, thermal properties, mechanical properties
Shredding <6mm Washing
Extrusion
Molding
Polymers and recycling17 DTU Chemical Engineering, Technical University of Denmark
Outlook• Challenges / Barriers
– Many different polymers, e.g. PP in various MW and with a range of different additives/residues.
– Plastics contain a number of residues after their normal life-cycle. – Highest quality products cannot be made from some of these
materials– What about all the other types of products?
• What is decisive for recycling?– Not so much the polymer – more the plastic– Clean fractions – design the products to provide clean materials– Mixtures of polymers – foils – barrier– Labels and other stickers on the rigid plastic
• Drivers– Market need (consumers or raw materials)– Economy, Base for production => increasing the amount of recycled
products/new products made from recycled plastics
Polymers and recycling18 DTU Chemical Engineering, Technical University of Denmark
Acknowledgements
• Marie K. Eriksen, Thomas F. AstrupDepartment of Environmental Engineering, DTU
• Jesper deClaville Christiansen, Department of Materials and Production, AAU
References:1. Eriksen, M.K., Pivnenko, K., Olsson, M.E., Astrup, T.F., 2018. Contamination in plastic recycling: Influence of metals on the quality of reprocessed plastic. Waste Management. DOI: 10.1016/j.wasman.2018.08.007
2. Eriksen, M.K., Christiansen, J.D., Daugaard, A.E., Astrup, T.F., 2018. Influence of product design and sorting systems on selected physical and mechanical properties of recycled plastic from household waste.