“Plastic” – One Word Does Not Sum It Up
I have decided that the word “plastic” and how we use it to descried so many materials is misleading. Plastic as a blanket term used for dozens of materials and polymers with similar characteristics. Although we call of these materials plastic, they do not all have the same properties, are not all recyclable and have different uses and chemical compositions.
Most of us are aware of those little numbers printed on our plastic containers: 1, 2, 3, 4, 5, 6, 7. But, do you know what they mean? And, what happens when a container does not have an identifying number? Because of my work with plastics I have done a lot of research and have learned quite a bit about the different chemical compositions and processes for recycling. We won’t get all “sciency” in this blog but I do feel that it is important for us all to understand this material a little better. I would like to give a brief synopsis about each of the major plastic categories and hopefully that will result in a better understanding of the complexities of this material.
#1 PET (Polyethylene Terephthalate): One of the most common plastics, uses include water bottles and food packaging. PET is recyclable but not recommended for reuse due to leaching tendencies over time and will break down relatively quickly into the environment creating micro and nano-plastic particles.
#2 HDPE (High-Density Polyethylene): HDPE is more rigid and resilient than PET and used for items such as milk jugs, laundry detergent containers, toys and plastic bags. HDPE is safe to reuse and recycle although only an estimated 30% is recycled in the US.
#3 PVC (Polyvinyl Chloride): PVC is commonly used to make plastic food wrap, hoses, plumbing pipes and even sheathing material for computer wires due to its density and tensile strength. Containing many toxins and prone to leaching, this plastic is nicknamed the “poison plastic” and is not considered safe for reuse or recycling.
#4 LDPE (Low-Density Polyethylene): Very similar to #2, LDPE is just softer and as the name implies, less dense. LDPE is commonly used as grocery and bread bags and squeezable bottles. Although considered safe for recycling, very few facilities are set up to process this material.
#5 PP (Polypropylene): PP is a very tough, heat-resistant and still lightweight material. Due to its properties for barrier protection PP is commonly used for food packaging such as yogurt containers and cereal bags in addition to being used to bottle medication at pharmacies. PP is considered safe for reuse but it not widely recycled.
#6 PS (Polystyrene): PS is a very inexpensive and lightweight platic commonly used as single use clamshell food containers, egg cartons and packaging peanuts. PS is not only considered unfit for reuse but it also has leaching tendencies and due to its weakness, also breaks down into the environment quickly creating micro and nano-plastic particles.
#7 OTHER (BPA, ABS, Polycarbonate, PLA, etc.) #7 is a “catch-all” for a growing number of polymers which not fall into another category. This includes materials like BPA, Polycarbonate, Nylons and Polyesters. It also includes new “compostable” material like PLA which are made from bio-based polymers and not chemicals. Because of this mix, #7’s do not have standard recycling processes and must be identified on a case-by-case basis.
So, there is your very basic overview of plastic polymers. Different plastics have different uses and some are more recyclable and reusable than others. This is why I have a hard time using the word plastic so regularly to lump these materials together. It creates an illusion that all plastics are the same when they absolutely are not. Not all plastics are bad and, I believe, recyclable plastics hadthe potential to revolutionize the world as a material that could be used, processed and reused over and over. Unfortunately, we went the other way with it and continue to create polymers that are cheaper to make new giving us no economic incentive for reuse and recycling. Because plastic is created so “cheaply” and sold at such low costs it has, in turn, created the false narrative that plastic as a material is of low value itself. It is due to this that we are using and disposing of it in staggering amounts to the extent that it is filling up our oceans and washing up on global shorelines.
Adding to all of this is the fact that not all plastic polymers in production have identifying labels or numbers. Plastics manufacturing is not a regulated industry and it is not required that all plastics be branded. Dyes and other chemical additives are also used to make different colors, textures and properties of plastics. Because of all the variations, it becomes much harder to recycle these materials together due to difference in composition and integrity. It requires advanced spectrometers and techniques requiring a large investment of time and money that most recycling facilities cannot afford.
To make a much longer story short, not all plastics are created equally nor are easy to identify. Some plastics have great recycling properties and others cannot be recycled at all. In addition, special additives to create colors, gloss, etc. further change to properties of plastic. I believe that part of the reason we are facing the global inundation of plastic pollution is our perception that all plastic is the same and our lack of understanding the complexities of the material. I challenge you to start to look at the polymers around you, start reading labels and let me know what types of plastic you see the most. Here, where I live, our mixed recycling bins no longer accept #5 (PP) so I am on a mission to create new products from it – I will certainly keep you posted!