Polymers or Plastics - Does it matter for recycling? · Source: Sandra Krautwaschl, Plastik Freie Zone. 3 DTU Chemical Engineering, Polymers Technical University of Denmark ... PET

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


The oil age world production 1859-2050

Source: http://scimaps.org/mapdetail/the_oil_age_world_oi_73


Current production of plastics

Source:Plastics Europe and Nova-Institute


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


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


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


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)


Eriksen, M.K. et al. 2018, Waste Management, DOI: 10.1016/j.wasman.2018.08.007.


Polymers applied in products

Source: PlasticsEurope Market Research Group (PEMRG) and Conversio Market & Strategy GmbH


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


Sample preparation

• Testing of prepared plastics– Composition, thermal properties, mechanical properties

Shredding <6mm Washing

Extrusion

Molding


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


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.

Polymers or Plastics - Does it matter for recycling? · Source: Sandra Krautwaschl, Plastik Freie Zone. 3 DTU Chemical Engineering, Polymers Technical University of Denmark ... PET

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