In today’s world recycling is one of the biggest buzz words. It seems like a no brainer. We take something old and give it a brand new life. We keep plastic out of the ocean and stop making new plastic. But, if it was so simple why don’t we have a huge plastic recycling industry?
What is Plastic Recycling?
Okay, Let’s start from the beginning. What is Plastic Recycling? Plastic Recycling is recovering scrap or waste plastic and reprocessing the material to make other useful materials. Unlike recycling aluminum, other metals, and glass plastic is very different. When you recycle aluminum your just melting aluminum and using it to make more aluminum. It is just one element it’s simple and doesn’t require any work. This is the same for other metals with glass it is a bit more tricky since its made of one compound, Silicon Oxides. The bonds in glass are stronger than that of plastic making it easier to mold and reuse.
Plastics are made from long polymer chains meaning they care composed of several different types of elements. Plastics are made of Carbon, Hydrogen, Oxygen and sometimes Fluorine. This makes plastics harder to keep their integrity when you try to melt them down and make them into something else. You’re breaking these bonds and the elements present in plastic are rearranging. Therefore there is a limited amount of times you can melt a plastic down and form a new compound. Chemically from the start of recycling plastic is already a bit more work.
What is the biggest issue?
One of the biggest challenges when it comes to plastic recycling is the cost. Plastic is cheap. Like plastic is dirt cheap. Recycling plastic often costs more than making more plastic which explains why we don’t see plastic recycling plants all over the US. Most of America sends its recycling to countries like China and Indonesia that can recycle plastic for cheap. Since we have to send our recycling away it isn’t a surprise that here in the US recycling is an afterthought. We place all our plastic in the bins and think that’s it. But in actuality, plastic recycling is more complex than that. For starters, a lot of the plastics we place in the recycling bn aren’t actually recyclable. So we send nonrecyclable plastic to China and they get pissed that we are sending them trash to burn. I know what your thinking. All plastic isn’t recyclable? Let’s get back into the Chemistry of Recycling.
Chemistry of Recycling
First let us define the two main types of plastics that exist, Thermoplastics and Thermoset plastics. A thermoset plastic is irreversibly hardened by curing. Basically, a thermoset plastic is rigid and it keeps its shape. Thermoset plastics are hard to melt and are firm. When we think of thermoset plastics we think of epoxies, silicone, polyurethanes, PVC and etc. Because of their rigid structure thermoset plastics are often not recyclable. When we think of Thermoplastics we think of plastics that move freely due to their flexibility. Thermoplastics are made from melting plastic into a mold. As a result, Thermoplastics like PET, are easily recycled. It is common to take a plastic PET bottle and make it into polyester to make fabrics used in the clothing industry. In summary, Thermoset plastics are often not recyclable and thermoplastics are recyclable.
This alone can make recycling plastic very difficult. Not all types of plastic are recyclable and different types of plastics have different methods to be broken down. Only if there was a way that we could label thermoplastics that are recyclable from thermoplastics that are not. I bet your thinking about the three arrow thingy on plastic bottles.
Recycling based off code
Here we get into the plastic identification code. This breaks down plastics into 7 groups of plastics that in theory are recyclable. The first one is the easiest. Plastic #1 is Polyethylene terephthalate or PET for short. These plastics as mentioned earlier are turned into polyesters to make clothes and carpets. These are arguably the easiest plastic to recycle.
The next two are #2 and #4 High-density Polyethylene HDPE and low-density polyethylene LDPE. Although both materials are made of polyethylene they have very different structures and in turn properties. When made LDPE has a lot of branching, think of it as a tree. This makes LDPE have a thinner crystalline structure than that of HDPE. As a result, LDPE tends to have a lower density and melting point. When we think of LDPE we think of plastic bags and opaque plastic squeezy bottles. When HDPE is made it has very limited branching, think of several branches of a tree winding together to make one large branch. As a result, HDPE has higher melting points and intern a higher density. These plastics are less opaque and stiffer. Think of the caps on your plastic water bottles and milk jugs. HDPE is more robust because it keeps its integrity after melting and in turn easier to recycle than LDPE.
Although there are 7 plastics on the list of recyclable plastic these three are the only ones widely recycled. Plastic #3, #5,#6 and #7 aren’t as cost-effective to recycle and recycling for them isn’t a widely used process. #6 Polystyrenes are arguably the cheapest plastic to produce making it hard for companies to incentive buying compactors or machines to recycle it. There simply isn’t any money in recycling polystyrene. While plastic #7 contains the notorious Bisphenol A or BPA. Which can be released when recycling it making it expensive to recycle #7 making it a small market.
So if #1, #2 and #4 are the easiest to recycle is most of these plastics in circulation being recycled? Not even close. As a planet, we generate so much plastic it is insane. In 2015 approximately 6.3 billion tons of plastic waste was generated. That is almost a full ton of plastic waste for everyone on the earth. Out of those 6.3 billion tons of plastic waste, only 9% was recycled while 79% of the plastic ended up in landfills. In 2018 globally we saw almost 20% of plastic waste recycled but we still have a long way to go.
Why isn’t all the plastic we can recycle being recycled? Because we are recycling wrong. Here in the US, we throw everything in those plastic bins believing we are making a difference when in actuality we are contaminating those bins and turning everything into waste. For starters, we need to place clean plastics in the recycling bin. When we leave leftover food or residue on our plastics it contaminates these bins. Making it easier to landfill everything in the bin to wash and clean everything inside.
Making a Difference
Rather than throwing out plastic in plastic bins hoping that it gets recycled, we need to start using less plastic. Recycling might seem like the golden answer to all our recycling problems but it is harder and more complex than placing our plastic water bottles in a bin. Rather than using single-use plastic bags, we can start using reusable materials. We can also start buying products made from recycled materials. If globally we show that there is an audience for recycled materials more recycled materials will be purchased.