I have to apologize – the "click" in “Asking You” section last time brought you to the question from the previous week. If you like, here is the question from last week : )
Today we start with a topic that everybody talks of but very few people really know about – how plastic is recycled. I like the topic because the science is intriguing and there are important lessons for the laboratory! Let's dive in, shall we?
Today's Lesson: How Plastics Are Recycled #1
Addressing plastic types and what it means for the laboratory.
Number Of The Day
Various sources and studies vary but on average it takes between 60-75% less energy to produce a new product from recycled plastics than creating it anew. Of course, the number also depends on the type of plastic as well (i.e., PP/PS/PET – more about what that means below).
67.5%
Upcoming Events & News
Towards Sustainable Procurement & Processes
Last week we have had our event about sustainable steps for every scientist – if you have missed it, there is a recording on Youtube that you can share with your friends. Next week we talk about how you can identify greener products to order. And if you do not know what procurement is or whether it is relevant for you, this session will teach you : )
Do You Know About LabManager?
There is a website that offeres some great articles on sustainability. As it turns out, they share all sorts of insight on how to run your lab, innovations, equipment and leadership. Soon they even have an online webinar about sustainability - Check it out right here -
Green Chemistry In Your Studies!
The American Chemical Society now requires every Bachelor’s Degree that they approve to include teaching about the twelve principles of green chemistry. A big step for sustainable science in education! – Read more here -
The Variety Of Plastics
To understand why recycling is not straightforward, there is an important lesson: Plastics are not Plastics.
1) Plastic Types
You probably have heard of them but in case have not, here is a little overview for you:
They are all polymers made up of Carbon bonds. For example, CH2=CH2 for Polyethylene (PE). Some come with more complex structures such as Polyethylene Terephthalate or vinyl chloride units for Polyvinyl Chloride (PVC).
Here are the most common plastics and the year they were first synthesized:
PET – Polyethylene Terephthalate - 1940s
PE – Polyethylene - 1930s
PCV - Polyvinyl Chloride - 1838
PP - Polypropylene - 1951
PS – Polystyrene - 1839
2) Recycling
Let’s talk about recycling:
At first, each of the widely used plastics caries a recycling number. This is what you commonly see on packaging (see graphic below). PET is #1 while P carries #5 and PS is designate by #6.
Plastics such as PE come in various densities (high, middle, low, low linear) that differ in their crystallinity. Of note, the nomenclature really varies here (HDPE vs PE-HD) so do not get confused : )
Of course, Aluminum is not a plastic but these recycling signs exist also for other materials. - here -
However, articles can contain numerous plastic types (such as tip boxes also contain polycarbonate for certain parts) and sometimes other additives that improve functionality. The symbol for other plastics is: #7
3) Why do these differences matter?
To be honest, this is the third time I rewrite this section. There are good reasons but there are many of them.
At first, one does not just create a new article from a mixture of various plastics. Thus, they (mostly) have to be separated before recycling (more about that next week). The reason is not so much that it is not possible to have composite materials – they do exist, are actively developed and often have superior qualities. However, many articles were originally produced from one type of plastics, and will therefore become one again.
Additionally, the proportion, “particle” size and quality of the different components has to be closely controlled, not only for the properties of the final product but also to produce it in the first place.
The reason lies in the different properties of these plastics. PET has a higher melting point than PP. Therefore, you would need to know how much of each plastic is in your mix to determine is melting temperature. Furthermore, depending on the design of your product, you want a specific shape or formation of the compontents (just think about fibers in a solid material to enhances the durability).
In fact, recycling PET is much more common than PP. This has to do with the properties of the materials (how easy is it to take the waste and make the new product out of it) and the costs of the recycling process.
Talking of costs, here comes a surprising fact. Recycling plastics acutally saves money. - read more here - or here -
Why is nobody doing it then? A) Because plastics are cheap, why saving on something that is not taking a lot of money anyway, B) you need specific equipment (=upfront costs) C) you somehow need to get the waste to your facility, sort it and wash it.
Pro Tip: In case you want to inform yourself and start googling, be careful! There are many sites that make claims that are not entirely true. For example, some properties of plastics are not straightforward. Take the leachability (i.e., the amount of components and additives a plastic releases into its environment). Some claim PET is much more likely to do so than PP – other studies prove the opposite. Similar can be said about “strength” of the plastic. Under which circumstances these properties are measured and which product one looks at (e.g., how thick or layered it is) matters a lot.
Applying The Knowledge
In the laboratory we work with a plethora of plastics.
For example, transparent bottles for your reagents or media are probably made out PET while you will find Low-Density PE in squeeze bottles. Your weight boats are made out of Polystyrene, that means if you just weight in NaCl and you rinse them, they are perfect for the recycling bin!
Reserachers in the University of British Columbia UBC's Point Grey Campus produces between 64 and 128 tons of laboratory plastic every year. However, not all waste is recyclable.
The used the following poster:
Check them out, they are awesome! The poster and much you can find - here -
And although it is obvious why they do not take contaminated waste, you now can also guess why they would not take all plastic products - because they are made out of a different plastic-types. Take Away:
Next Lesson:
How do we handle all these kinds of plastic and how can we separate them?
Making It Your Lesson
Please share your opinion whether you think the lesson was a bit too long this time or whether you want more detailed insight - A Google Form With Just 1 Question - Thanks A Lot!
Asking You
Which is with 26.9% the most produced type of plastic worldwide?
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