It is difficult to recycle plastics due to several key factors:
- Diversity of plastic types: There are thousands of different kinds of plastics made from different polymers, which cannot be melted and recycled together because they have varying melting points and properties. For effective recycling, plastics need to be sorted into specific types, which is labor-intensive and costly.
- Contamination: Plastics used for food or oil containers often have residues that make them unfit for recycling unless thoroughly cleaned. Contaminated plastics are often discarded rather than recycled, adding to costs and inefficiencies.
- Degradation of plastic quality: Each time plastic is melted and reformed, its polymer chains break down, leading to lower quality recycled products. This degradation means recycling plastics repeatedly is limited and often results in downcycling (lower quality products) rather than producing the same quality plastic.
- Additives and multi-layer plastics: Many plastics contain dyes, flame retardants, plasticizers, and other additives that complicate recycling. Multi-layer plastics used in flexible food packaging are also very hard to recycle mechanically.
- Economic factors: Virgin plastic is relatively cheap due to inexpensive raw materials (fossil fuel byproducts), and recycling processes require costly sorting, cleaning, and processing. Often, the energy cost and investment to recycle plastics are higher than producing new plastic, making it economically challenging.
- Infrastructure and market issues: Recycling infrastructure is unevenly distributed and often incomplete, and the lack of buyers for recycled plastics further discourages recycling efforts.
In summary, the difficulty in recycling plastics arises from their chemical diversity, contamination challenges, quality degradation upon recycling, presence of additives, economic costs, and inadequate recycling infrastructure and market demand.
This comprehensive understanding explains why plastic recycling rates are low globally and the ongoing challenges in improving plastic recycling systems.
