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Engineering for the Environment - Part 2: Recyclable vs Recycled Plastic

Engineering for the Environment - Part 2: Recyclable vs Recycled Plastic

The road to landfill is paved with good intentions.


If you have purchased or used a “sustainable” gel pack in the past few years you’ve probably seen the above decal – the famous #4 recycling symbol which corresponds to Low Density Polyethylene (LDPE). LDPE is used for gel packs because it's flexible, it has good sealing properties. it doesn't get brittle when cold (with proper additives) and it's relatively cheap.

According the the EPA’s “Advancing Sustainable Materials Management: Facts and Figures 2018”, only 4.3% of LDPE generated in 2018 was recycled.

That means over 95% of the “sustainable” gel packs out there either went to landfill or were or diverted to Waste-to-Energy facilities, which is where material is essentially incinerated to generate electricity in a very dirty way. Think burning petroleum. Bad news.

Why is the recycle rate for LDPE so low? It’s not because consumers don’t want to recycle – we see significantly higher rates of recycling for other types of plastic resin like PET, the plastic used for water bottles. Its because recycling LDPE is hard. Unfortunately most gel pack companies use virgin LDPE in their products but claim they are recyclable.  

Why is LDPE hard to recycle? For one, it’s very inconvenient for consumers. In most municipalities in the United States LDPE is not curbside recyclable. If you are asking a consumer to empty their gel pack, clean the empty wrapper of contaminants, get into their car and make a trip to the nearest MRF (Materials Recovery Facility), which are referred to verbally as “Murphs”, then your recycling strategy is doomed. Even when said consumer gets to the MRF, chances are the MRF won’t take it.

You may be asking, LDPE is a widely used plastic - why isn’t LDPE curbside recyclable? It’s because it’s not profitable right now.

To understand that last sentence let’s level set on the recycling industry. The reality is recycling is a business and the laws of supply and demand apply. Plastic recyclers are manufacturers of commodity products and their success depends on securing a steady supply of uncontaminated raw materials and having a demand for their end product.

Right now, there is not enough demand for recycled LDPE to warrant a curbside recycling program. It is not sought after enough, it is not valuable enough.

There are also some supply and processing issues with LDPE. MRFs are primarily set up to handle current curbside recyclable plastics: #1 PET and #2 HDPE, which can be thought of as those screw top bottles, gallon milk jugs, etc. Their sorting and grinding infrastructure is set up for these hard plastics. LDPE Plastic bags and films get wrapped around conveyors and sorting screens and are generally difficult products to recycle if the MRF does not have the relevant infrastructure. There are certainly facilities that can handle LDPE but they are not ubiquitous and they do not draw from curbside recycling.

But don’t lose hope. This is all a circular reference, and we can use the same laws of supply and demand to fix this. If there were more demand and the recycled LDPE were more sought after, MRFs would invest in infrastructure needed to recycle it efficiently. A supply chain would be formed to get inputs to the MRFs, vis-a-vis curbside recycling programs.

We believe the answer to including LDPE in the circular economy is to create demand for recycled material. This will drive up the value of the recycled material and create the consistency of demand needed for recyclers and communities to invest in the infrastructure, education, and pathways needed to recycle #4 plastic.

Instead of just slapping a #4 symbol on our gel packs and washing our hands of its inevitable trip to the landfill, we are using material that’s already out there and proving a business model that thrives off of recycled plastic. There are some geographies and strategies that have been successful recycling #4 plastic such as in store drop off for grocery bags. We know it's possible. Minus Works has been sourcing high quality recycled content from these strategies to use in our gel packs. Why generate new plastic when we can reuse what’s already been generated?

Why don’t other gel pack companies use recycled material? It took some innovation and development to get where we are. We have constructed a laminate that uses recycled polyethylene on the interior of the film, with a thin layer of virgin material on the exterior so as to keep our FDA approval for direct food contact. We have learned a lot when it comes to using recycled LDPE and achieving the right oxygen and moisture barrier properties and the right sealing performance.

Want to incorporate recycled material into your packaging? Send us a note, we are excited to hear from you.

Email us: cs@minusworks.com