In today’s world, the sustainability of products and production processes is at the forefront of consumer awareness. Conventional plastics, when not recycled, eventually end up in landfills, rivers and oceans, where they pose a threat to plant and animal life in these ecosystems due to their lack of or complexity in biodegradability.
Most of this plastic waste comes from single-use products. One way to address this problem of plastic pollution is to recycle plastic products after they have been used by the consumer. Plastic recycled after consumption is referred to as post-consumer recycled plastic or PCR plastic.
The technologies and processes for processing post-consumer plastic are improving and getting more efficient. Yet, they still face challenges.
What does post-consumer recycled plastic have to offer? Perhaps the most important paradigm shift is a shift from a linear economy model to a sustainable circular economy model.
In this article, you will learn about:
What PCR plastics are
How PCR plastics are produced and used in manufacturing
Why PCR plastics are important
The challenges and future of PCR plastics
Figure 1. Plastic recycling codes representing the different types of plastic
What is PCR plastic?
When a plastic product contains recycled content, this content may originate from one of two sources: post-industrial waste or post-consumer waste.
Plastic material that is recycled from plastic waste after it has been used by a consumer is referred to as post-consumer recycled plastic (PCR plastic).
PCR plastic is different from plastic waste from industries that are being reused in the production line to minimize wastage - otherwise known as post-industrial recycled plastic (PIR plastic).
Post-consumer recycled plastics are collected not only from recently discarded waste such as household waste but also from oceans, beaches, rivers and places where they may pose a significant environmental threat.
In the current manufacture of new plastic products, PCR plastic is often mixed with virgin plastic to maintain the property requirements of such products. This is due to the fact that recycled plastic may suffer from polymer degradation as a result of various contaminants found throughout the recycling stream.
In some cases, such as food packaging, regulations may prevent the use of PCR plastic altogether. This is because of the uncertainty regarding their sources and harmful impurities they may contain, which may migrate into the food and cause health problems for consumers down the line.
Food packaging should be inert and not release its constituents into food even at elevated temperatures. Regulations from government bodies such as the FDA and the European Commission outline considerations and concerns about the use of PCR plastic as food packaging.
Generally, PCR plastics can be reused for the same function for only a limited number of cycles before they become too degraded to meet those specific performance requirements. When this happens, they are downgraded to be used in other ways such as insulation, decking, fabrics and carpeting.
Table 1. Classification of plastic waste [1]
Plastic Waste
Pre-consumer waste
Post-consumer waste
Municipal solid waste (MSW)
Other wastes
Production waste
Residential
Distribution and Industry
Damaged goods
Industrial
Automotive
Commercial
Electrical and Electronics
Institutional
Construction and Demolitions
Agriculture
Production of PCR plastic
The production of PCR plastics occurs in much the same way as recycling plastics for reuse in general. The major difference is in where the recycled plastic comes from.
The process of recycling plastic follows four possible methods depending on the homogeneity, cleanliness and quality of the plastic waste collected [3][4]:
primary recycling
secondary recycling
tertiary recycling
quaternary recycling
Only secondary and tertiary recycling produce what is known as PCR plastics. Primary recycling reuses industrial plastic waste, while quaternary recycling destroys the plastic to recover energy and create power.
Secondary or mechanical recycling
This process is limited to thermoplastics (plastics that can be melted and moulded repeatedly). It does not entail alteration of the molecular structure of the plastic. Instead, it involves the mechanical processing of the plastic after it has been sorted by colour, size and shape.
Plastic is processed into plastic pellets that can be used in the manufacture of new products. However, there is usually a reduction in the quality of the products made from this recycled material. To mitigate this problem, virgin plastic is often mixed in with recycled plastic.
Tertiary, chemical or feedstock recycling
This process involves the complete or partial depolymerization of the plastic into monomers or oligomers respectively through chemical reactions. The resulting monomers can then be polymerized to produce the original polymer or new ones.
Companies such as Lavergne and Sabic are leading producers of PCR plastics such as polyphenyl-ether (PPE), high-impact polystyrene (HIPS), polycarbonates (PC), High-density polyethylene (HDPE), polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS) and polymer blends which contain high PCR plastic content.
Recycling companies create programs that incentivize their clients to sort and return plastic waste. They sustain long-term relationships with other suppliers who supply them with high-quality feedstock. Some of their processes are proprietary, but they generally follow the same general procedure outlined above.
The importance of PCR plastic
Recycling from industrial waste is considerably easier as it entails simply reusing excess leftover material from the production process. Although recycling becomes more complicated when the plastic in question is thermosetting plastic, greater production efficiency can drastically reduce waste production and incorporate its reuse as seamlessly as possible.
Therefore, there is not much room for improvement, environmentally speaking, from this stream of plastic waste as it is already in the best interest of manufacturers to minimize waste.
The majority of plastics are used for packaging and are largely disposed of improperly, which greatly increases their likelihood of contamination. For this reason, recycling plastics from post-consumer sources is relatively complex and expensive. Given that this stream of waste is the largest and most problematic, finding a way to reuse this waste promises great environmental benefits such as a reduction in Global Warming Potential (GWP) and Cumulative Energy Demand (CED).
A case study comparing the environmental impact of two resins, Valox iQ and Lexan EXL 8414 (which contain 60% PCR polyethylene terephthalate and up 50% PCR polycarbonate respectively), against their unadulterated counterparts, showed significant GWP and CED reductions.
Valox iQ resin has the potential of 46-49% reduction in GWP and 54-57% reduction in CED, whereas Lexan EXL 8414 has the potential of 7-36% reduction in GWP and 10-45% reduction in CED, depending on the quantity of PCR polycarbonate it contains [2].
The use of PCR plastic can reduce both the amount of waste that would contaminate the environment and the waste that is already prevalent.
The environmental benefits from using PCR plastic can be summarized as follows:
Less plastic pollution and direct positive influence on ocean cleanup
Less dependence on fossil resources
Reduction of greenhouse gas emissions
Less water, energy and resource consumption
Less plastic that goes to landfills
Contribution to sustainability and a circular economy
Figure 2. Discarded plastic bottles stacked for recycling
The challenges and future trends of PCR plastics
With the current trend of plastic production deemed rather unsustainable, PCR plastic could be the way forward. The raw materials required for PCR plastics are not extracted from petroleum products like their virgin counterparts and are already considered worthless after being discarded. It's when they are properly sorted that they begin to have value.
Unlike virgin plastic, PCR plastic has price stability since most waste materials are not subject to fluctuating petroleum prices.
Although the efforts it takes to source, sort, and clean waste plastic from a myriad of shapes, sizes and colours are expensive, there are technologies in place that automate parts of this process, making it cheaper.
Generally, products made from PCR plastic are often not of the same quality as those made from virgin plastic due to the inevitable inhomogeneity in the waste plastic. However, new technologies from companies like Lavergne help produce high-quality, 100% PCR plastic products.
Currently, public awareness is a strong motivation as many consumers prefer to use eco-friendly products. Manufacturers are pivoting accordingly to satisfy this public interest. Laws, regulations, and their proper enforcement are required to keep pushing manufacturers into using PCR plastic. All in all, it's still early stages in the journey of PCR, but we are certainly moving in the right direction.
If you enjoyed reading this article, you can read more related content here:
If you have any questions on Post-Consumer Recycled Packaging, pcr materials, Post Consumer Recycle PET. We will give the professional answers to your questions.