How Many Times Can Plastic REALLY Be Recycled?
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- เผยแพร่เมื่อ 9 พ.ย. 2023
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In this video, we’re testing the highly debated topic of ‘how many times can plastic be recycled?’. Looking online gives you a whole host of mixed results with a lot of generalisation about ‘plastic’ as a single material. We decided that we were bored of people using this as an excuse as to why ‘recycling doesn’t work’ and decided to test this out for ourselves.
To be super clear about our tests - we’re using recycled HDPE and running it through our machines at 230 degrees celsius. The plastic is only melted for as long as is necessary and doesn’t ever go beyond this temperature. All of our plastic comes from post-consumer waste sources and we are very careful about sorting, separating and cleaning the plastic before we let it enter our material circulation.
We’re fascinated to hear what you think of these results. We absolutely could have gone beyond 30, but we weren’t expecting the plastic to last as well as it did to be completely honest with you! We can also repeat these tests in other materials to see if the results are similar, so let us know if that’s something you’d like to see.
Oh, and here's a link to our carabiners if you fancy one!
www.brothersmake.com/shop/p/c...
#BrothersMake #HDPE #PreciousPlastic #HDPERecycling #RecycledPlastic #RecycledPlasticBottles #PlasticShredding #InjectionMoulding #PlasticRecycling
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Haven't checked the site yet, and I'm going to just after posting this comment, but seeing all those colored planters had me wondering if you guys have some nicely colored rpg dice sets made of recycled plastic....
From the injection molding background my self. Poly/HDPE can honestly be recycled loads of times. It’s when you get into your glass filled or carbon filled materials where they can only be recycled 4-5 times typically because of the strength of the material starts to degrade more and more.
lol recycling logo... you me resin identification code
How about chemical recycling?
Aka, the plastic is chemically decomposed into smaller molecules, purified and finally re-polymerised.
I don't know about where you live. But here the plastic caps of the bottles are different plastic from the bottle it self. Those do not mix well. As you can recycle plastic if it is the same nr and all that. but mixing in other will make it degrade/stable/reusable on a entire different level. So i hope it is printed on the caps. Because if not. You are mixing types there ;)
If there the same, i would say there is no real limit on the recycle times. If it's the right treated plastic.
I think the constraint with the amount of times you can recycle plastic is not necessarily from the recycling process itself (as proven in this great video), but from how the product is used between being recycled. For example if the caribiners were used on a daily basis and exposed to lots of UV (someone who works outside alot, construction etc) the plastic may degrade due to UV exposure and lose strength over time. Other factors such as load stress, temperature and exposure to chemicals need to be taken into consideration between each recycle step. The way in which the product is used ends up defining how long the material will last before degrading to a point where it loses it's virgin properties.
That’s literally exactly what I was gonna say. I think the environmental conditions that each “lifetime” of the plastic is exposed to reduces its recyclability
I absolutely agree. I was thinking of the same thing, and while this is a very nice video, I also thought that the way these recycled plastics are to be used for a prolonged period of time before getting recycled again should be a big factor to take into consideration when truly determining the number of times it's actually gonna get recycled before it breaks apart. And that takes waaay more time than what was shown here in the video. But I think it can still be done in a short span of time, by actually intentionally exposing these plastics to harsh conditions or stress before getting recycled again.
I was thinking this too. I think it's honestly a safe bet that realistically you got maybe half of the amount of times they tested here to work.
I agree with all that you 4 people have said, except the stress from usage I'm not an expert, but I'm guessing after watching this video that the stress is reset after/during heating.
I'm sure that we need proper lab work to confirm what I said, though.
@@eugenetswong Exactly, not so much stress, but UV, chemicals, etc - basically anything that reacts with the plastic to change its chemical properties could affect its recyclability.
That being said, I don't think the problem is insurmountable because things like steel undergo chemical corrosion as well, yet are infinitely recyclable.
Australian government should support small plastic recycler businesses instead of exporting plastic to other countries
Couldn't agree more!
It should be illegal to export your trash and plastic. You create it, you get to deal with the repercussions.
@@TheFiftyQuid tell that to the government
The CSIRO has been actively researching recycling for at least 3 decades. In Australia pure stream industrial recycling (analogous to the Brothers) is fairly strong but domestic recycling has problems WRT: collection, contamination, sorting, cleaning and UV degradation.
Yup, we are totally thrilled for your trash here in the Philippines..
Maybe you should do a strength test. See how much it can hold before breaking.
Some friends of ours actually have a tensile testing machine - so we may have to give it a go!
I would love to see that!
That would be awesome! @@BrothersMake
That's awesome to hear I was going to suggest a tensile strength test. Also compression test. I did expect them to become more brittle, but these results are fantastic and unexpected.
@@BrothersMakeyou could also try giving a few goes on the tensile strength and then recycle them a few times returning to the machine each time. just an idea!
You are 100% right about clean and well sorted plastic should have a much higher recycle rate than what is advertised. However the recycling system is broken. With still many items not being cleaned properly, bad labeling and companies creating laminated products containing many materials. The system needs to change! And the only way to do that is through changing our buying habits and supporting the small businesses that make an effort to recycle better, smarter and put in that time! Eg. Brothers Make!
However as for the results dont forget that you guys utilised similarly sourced HDPE, with similar properties. However even the category of HDPE in the industrial recycling system can have a wide variety of additives that would affect your success. Also the carabiner is quite a thick object in injection moulding terms. I wonder what the results would have been on a 1-2mm product and what the results would have been with the standard tensile, compression and lateral load tests. Maybe video 2?
Honestly only policy can make manufacturers conform to a shared standard for recycling. Here in germany we have 100% recyclable Pet bottles through a uniform collection and distribution system.
as long as its cheaper for me idc
@@speicalkeek4579 the only true way to change buying habits
Properly recycling plastic also requires A LOT of consumer knowledge and willingness to recycle. Because there are many different types of plastic and they all have different additive components to regulate their form and function. Its just difficult all around.
We can agree that the recycling systems aren't perfect, but saying "oUr SyStEm Is bRoKeN" just makes you sound like a petulant child and you insinuate that recycling systems were ever perfect in the first place. It has always been a work in progress and is improving all the time.
Another thing to think about is that the carabiners and cups are pretty thick plastic (relatively to the thickness of bottles) - and everything is injection molded, not blow molded. I don't know the exact split, but most of the things that you come in contact with are blow molded, not injection molded. Injection molded parts are definitely going to have more strength in general because they're thicker. In addition, you might see a difference in the tensile strength of the carabiners (though I understand why you might be reluctant to do strength testing of them on camera). But if you make a 1L blow molded bottle and try to do a 3' or 6' drop test, you may see differences MUCH earlier than 30x.
So I’ve worked in industrial injection molding for 3 years and industrial thermoforming for 5 years. I am quite surprised at the results of this test. Granted I’ve not got a lot of experience with HDPE: mostly with PolyPro, PLA, Nylon (glass-filled and normal), TPE, and TPU. But nonetheless in my current thermoforming job we use our reground material but we mix in %50 virgin material to dilute the degraded plastic. I am curious about the temperature settings for your two machines and how those may have affected the results. If you injected at the lower temperature ranges it would have resulted in somewhat less degradation per run (not sure if the amount is negligible thought). Lastly, those injection and extrusion machines are SO COOL. I’m only used to seeing giant machines with 30ft long barrels, so seeing such small machines is just super awesome to me.
Wait till you see a 3D printer then... jokes aside, there are actually really cool DIY extrusion machines you can build to reuse 3d printing filament and it's just freaking awesome
This seems to be a good small business opportunity. Or even a chain of businesses. Lots of positive possibilities.
I would love to see a long-term environmental test followed by recycling to see how the plastic degrades (or doesn't) in different scenarios.
Like, put a batch outside for a week, a batch on the window sill getting sun, maybe a batch in and out of the freezer daily to simulate thermal cycling and of course a room temp control group. Shred those batches and re-do the carabiner test to see if any of the plastics are now weaker.
That was always my understanding - the change in strength wasnt from the shortening of polymer chains etc, but from the added impurities after each use, recovery, and processing.
But that not from work in the industry or anything, just what i was told in school in the 80s
You do a fine job of keeping the plastic clean, not a good example of post consumer mixed recycling. Maybe that's the point.
My very first search about the topic gave me a link to a paper the abstract of which reads:
"The thermomechanical degradation during processing gives rise to different modifications of the structure depending on the temperature, residence time and applied stress. In general, it is possible to say that if the reprocessing operations are carried out in apparatus with low residence time, the mechanical and rheological properties of the raw materials are only slightly influenced by the recycling operations. Significant degradation phenomena and reduction of some mechanical properties are observed on increasing the number of recycling steps in apparatus with large residence times. By adding antioxidant agents the polymer maintains the initial properties even after several recycling cycles."
Would love to see this done with other plastics and also think if you threw everything in a room with a UV lamp on for a few days between recycling steps to see if there’s a noticeable difference in strength of the batches.
Anyways, cool video and enjoyed watching you test this one out.
I think the other thing to consider is that you rarely recycle a product immediately off the production line. It usually spends months on a shelf somewhere, more months or even years being used, and then more months at the end of its life as it's processed, cleaned with harsh chemicals, and finally ground and reformed. All that time likely contributes to the expected degradation of the polymers.
Love that you did this this as a bit of self-researcher, myself. It’s always easier to trust your own results than those someone else has done because you control all the variables that matter to your own things.
100%! So interesting to find out for yourself for sure - especially when no one can agree on an answer!
Plastic degrades over time. The limit to how many times you can recycle it is because it ages and degrades in a way that melting and recasting doesn't fix, leaving you with decayed plastic in a freshly-injected shape. You can grind it and remelt it and reinject it as many times as you want, that doesn't degrade it. You're not really recycling it because it wasn't used until it decayed and broke over time. It's still fresh plastic. It spends years being a bottle and decaying, then you try to melt the decayed bottle into a cliphook, and you get a cliphook made of decayed plastic, and that breaks. You're making cliphooks out of the same fresh plastic, no matter how many times you grind and melt that plastic. It's still only a few days old. The recycling limit is because used products that get recycled are old, and you're mixing together old decayed plastics to make another thing, which continues aging until it too gets recycled, until it's so far decayed anything you make fails.
Interest video. HDPE actually performed much better than what I expected.
I will just add some more information here. The problem with giving you an exact number of times plastic can be recycled is not that there is some sort of agenda to keep that information from you. It is genuinely complex, as there are so many variables involved. To name a few:
1. What plastic are you using? - obviously
2. How well can you clean them? - In a small operation like in your workshop, and regrinding the material immediately after extruded, your samples are very cleaner.
3. What is the thermal history distribution of the mix? - basically, what if you mixed batch with different heat cycle counts. You actually did this to some extend, I think, by puting everything in the same extrusion moulding machine.
4. what is the shape of the object you are making? - The thinner the wall of the object the harder it is to make via recycled plastic. For example, recycled plastic bags (which you can buy in the ) are noticeably easier to tear than virgin plastic ones.
5. etc.
All of this make plastic recycling extremely unapealling. As anyone want to try it on an industrial scale must always invest tons of money up from to even know if the final product is even viable. This is compounded by the lack of recycling policies (in sorting trash) and consumer awareness (e.i. remove the lit/warping off your food-packaging/soda-bottle and give everything a rinse before binning. - this make a world of different, btw).
Great video - boring to do but of such value to the community. I had exactly this question. Thanks very much for your effort!
Thanks Keith! Fortunately the boredom was easily fixed with a fair few Podcasts 😅 glad we could help.
This is a great thing you guys are doing. Your test uses clean, on-site, premium post process material. Post consumer material is...glorified trash. The efficiency goes down and so does the $$$$ incentive.
In the industry, enforcing any rules all grinds down : $$. In Metal Fab for example, the most efficient subcontractor wins, whether it's cutting corners, better processes or material costs.
In my region of Canada, recycling and garbage are hard to distinguish, even for educated people, judging by the sheer amount of recyclable matter in the garbage and vice versa.
Glass contaminates the fibrous materials and the plastics, the plastics contaminate the glass and fibrous materials... And since it's expensive to process, the stuff is sent overseas or buried.
Ironically, clean sorted materials are worth $$$, cardboard bales have companies that pay you to pick them up!
It's also a pain to bring back cans and bottles to stores for refund...I wish we could have a local system where it's actually easy to just shove plastics/glass/ferrous/etc down a specific drain where it gets shredded/compacted and picked up by the appropriate industry.
Polystyrene Foam should be easy to recycle, but the very low density makes it a pain. I have the equivalent of a solid cubic meter of accumulated polystyrene packaging dissolved in half a liter of acetone in a couple jars. No kidding.
Good on you for seeing a lot of conflicting information and deciding to put it to the test so there's more real world data.
Ah thank you so much, it was a super interesting video to make!
I did a literature review on this (or recycling PLA into new fillament for FDM printing to be more specific), and one of the most interesting findings was that adding around 1/3 virgin material when recycling would always give a very usable result with relatively good realogical properties, even when the other 2/3 had been recycled many times.
A better measurement in material change after each round of recycling would be to put all of the sampled carabiners in a tensile testing machine and seeing how much the yield strength changes over time. It would require more than one of each round's sample to get an accurate average yield strength though.
Brilliant video. You’re definitely right about recycling centres getting a mixed bag of quality but this shows what COULD be done!
The big recyclers don't clean thoroughly. I heard that one teaspoon of peanut butter in a not cleaned peanut butter jar can ruin a Dozen kilograms of recycling.
Well duh.
Chemistry student here. There's two main categories of plastic, thermoplastic and thermoset.
Thermoplastics melt when heated and are much easier to recycle as a result. Sometimes, as in the case of PE [includes HDPE, LDPE], infinitely recyclable barring contamination.
Thermosets harden when heated, making them difficult to recycle. You can't melt them down, so you have to use chemical means of breaking them back apart into their monomers, which isn't always possible.
Also, you got the terminology wrong here. You were saying the carabiners were strong because they weren't breaking, but that's the opposite of the truth. Their elasticity is what allowed them to not break. Strong materials are brittle. When too much force is applied, they snap. Weak materials are elastic. When too much force is applied, they bend. Nothing is perfectly strong or perfectly elastic; real materials exist on a spectrum between the two.
Plastic actually gets stronger when heated or exposed to UV light or ozone. Specifically, the long polymer chains will get cross-linked began two side to side chains. This forms small off color, typically white, thermoset dots in the product. The more you recycle the plastic, the slightly larger these dots become. Because they no longer melt, if you recycle enough times, they'll clog your extruder nozzles. They're also stronger than the original plastic, which makes the plastic less elastic and more brittle.
If you've read this far, you should make an update video looking closely through a magnifying glass and microscope for those dots.
It would be so cool if we could have neighborhood plastic recycling centers like we have post offices and drug stores- they'd take and sort the plastics from people's and businesses' recycling bins, and recycle it to create new things that people can buy- household items like storage bins, clothes hangers, food containers, reusable grocery bags, toys, etc. or create larger orders of items for businesses.
Again, proving something we have been taught being absolute nonsense. Cheers for testing this in such an honest way. Placing my order for a carabineer right now!! 😁
You are far too kind, sir! 🪄
Very surprised to see that HDPE can be recycled at least 30 times! Although that doesnm't come close to the potential of Polystyrene. With PS, you don't even need to melt it down, you can just thermally depolymerise it, recover the styrene, and heat it with Benzoyl peroxide to turn it back into Polystyrene. Alternatively you can perform the latter step using something like benzophenone (radical photoinitiator) and blast the styrene monomer with UV to the same effect.
"recover the styrene" is the yucky part. I would not want to be around this monomer at home or in a normal workshop. Fume hood please.
Excellent research video guys, pushing the boundaries of plastic. Keep up the great work😀👍
Great work guys. Thanks for investing the time to find out the truth. You say your setup is not controlled, but you are underestimating the care you put into your processes. I love the addition of the first time recycled white to add the colour differences back in. Keep up the great content.
A lot of it depends on the material. PET and PE will recycle practically indefinitely, but PLA (of 3d printing fame) shows significant degradation after a single pass through a recycling setup. (It can still be practically recycled if mixed in with about half virgin pellets, though.)
Love to see a practical experiment though!
P.S. You guys should totally make an "S-hook" style carabiner with two spots, one for your bag's strap and one for your keys.
I'd actually be interested in knowing which properties are affected by repeated attempts at recycling - how does the degradation manifest itself?
Easy degradation is a feature of PLA. It isn't even intended for long-lived application.
Interesting. I remember seeing a bit of a similar test with recycling 3d printing filament. I think it may have been with ABS and they definitely started to have problems with 3d printing it after a few rounds of grinding/melting. I think the issue they had was dust and moisture inclusion that was causing bubbling/popping as they tried to extrude it while printing.
I'm glad you put in the rock-climbing disclaimer as I was thinking I wouldn't even let an Action Man doll rappel using recycled plastic carabiners.
It looks like the marbling evened out and became a solid color over time. Great experiment.
For sure - by round 4 all marbling had pretty much gone! Was nice to see that when we cut it with white again at the end, the marbling came back in full effect though! Thank you Joseph 🤙🏼
@@BrothersMake Thank you for making content like this. It's going to inspire people to recycle more and reuse materials as much as the can. I'm trying to reuse the tires I just replaced on my car. Any ideas?
Fascinating. Thanks for doing this. Just shows what can be done with a little effort. Yes, I would be interested in seeing what happens to other sorts of plastic.
Glad you found it interesting! Noted, we're definitely keen to try out another so we'll get on it ♻️
Fantastic work, guys! I hope you’ll get around to testing this same thing with a variety of other plastics. I’d love to see how many cycles common 3d printing filaments can go through.
Wonderful video, love this kind of methodical testing. Just recently did a series of tests with a bunch of waste plastic from a warehouse: multiple jars containing water, vegetable oil, and a 50/50 IPA 70% to water mix to determine "good or bad" -> "PP or HDPE/LDPE" -> "HDPE or LDPE". Messy, took a bunch of time, but cemented for sure what I could use and what was functionally worthless for these projects.
Thank you so much for the interesting test!!
That overdub was clean af and I don't think I would have noticed if you hadn't said it was.
I really enjoyed watching this and if you guys had the time I'd be interested in seeing the process done with other plastics. It's very educational.
Thank you so much! Very useful info. I was mad no one actually knows the answer to this question
Great video. It would be fantastic to see further videos of different plastics.
Thanks so much - noted!
@BrothersMake I really appreciate the work yous put in to making products, content and challenging plastic norms.
What this tells me is that the pieces you have to cut off the finished product can be reused with no fear. This video answers that question for me. What you said at the end makes sense. I do notice that every plastic you use looks very clean and you have everything exact. I think if you were to collect some of the items you have made after a few years of normal use and recycle again, there may be a noticeable difference from factors such as UV light as others have commented.
It always makes me happy to see how people reuse and recycle items. Answering questions like this video does are also enjoyable. Thank you.
Found this absolutely fascinating. Thank you x
Great video. I learned something new today. I do send your videos to my students sometimes. Many of them are quite sensitive/interested in this kind of content. Keep it up.
Ah that's great to hear - thanks for sharing!
I think you can recycle plastic a LOT more! As long as it's use changes too. The first (maybe second time too) recycle could pretty much be used as anything. After a certain amount of recycled, the hygiene/waterproof/durability level becomes too low for general use, it could still be recycled into outdoor tiles, counterweights or anything that doesn't have to hold big weights.
I think there's a lot more possibilities, but it's just not researched well enough at this point. If there's a generalized standard we could follow, that'll be a possibility. For example: if we know a certain type of plastic is safe to be used in food/drink storage up until two recycles after initial production, these plastics could be sent to a factory that produces recycled plant pots. If it's no longer good to use it in hollow/open structures, it could then be sent to factories making bricks and so on.
We're nowhere near that level of recycling, but it would save a lot of trash in my opinion!
Awesome video guys!
Such a cool idea and well executed!
Very nice demo of engineering and testing!
Excellent video I’ve often wondered how many times hope can be reused too! Thx for a non biased answer
Bloody love you guys 😊😊😊 !!! Thank you for sharing the experiment with us and the learning 🙏🙏🙏. 😎
Thanks John! 🙌🏼♻️
This was fab, I'd love to see this repeated with another material.
Yeah, like another plastic.
Great test guys, thanks for sharing
Step 1, sort your HDPE by color
Step 2, just shred it all together.
Genius.
Yes! Such a confusing topic! Thank you!! I do a lot kf remelting because im a beginner and a lot kf my things dont turn out quite right. Good to know i have a lot of room for error!!
This got my sub! More more more!!! Thank you. This is fugging awesome!!!
what an incredibly useful video to call out companies that are against our 10c return on plastic bottles
Absolutely amazing work as always
Yes!!
Historic / Legendary video gentleman 👏
(Been wanting to try this for months with TPU on our discs.)
Ah thanks so much man, it has been on our list for a fair while too! Was super interesting to try out. Hope you're keeping well, brother 🤙🏼
I'm still stuck on the fact they took all that time to separate the colours...only to throw them all back in the same bin.
i just stumbled uppon your channel - amazing guys keep it up
Small company making old into new.
Big thanks for this Brothers!
Totally fascinating! Y’all are total legends!
Far too kind, thank you!
Two of the biggest things that limit plastic recyclabilty (look ma, new word) is 1. Weathering of the plastic which can consist of but is not limited to UV breaking down the plastic into weaker breakdown products, heat doing the same thing, even acidic rain- and 2. Contaminates. In order to recycle, you have to prewash the plastics- and many things don't just wash off with the commonly used solvents. It only takes one person using a plastic bin as an emergency oil container to contaminate a batch. This also has something to do with differing plastic types getting into the batch and even the colorants mixing together at percentages that weaken the mixed plastics.
I would love to see a video where you test each generation to the point of failure. Great video. Made me subscribe.
Thank you for empowering and educational content 😊
Our pleasure! Thank you 😊
Really good quality work guys
It'll be interesting to see it with a tensile testing machine.
It would be! Some friends of ours actually have one so we'll have to try it out.
@@BrothersMakecan't wait to see that test results....
I have some experience in plastic injection molding using natural acetal, pellet colored abs, and pellet colored polystyrene so I will just give my thoughts. Acetal being an engineered plastic would be heavily reliant on the oils for bonding so I would assume there would be a much bigger difference between 1 to 30 times recycled. ABS has so much off gassing I have to imagine there would be something lost after all those cycles. Polystyrene on the other had can be recycled quite a bit but with some drawbacks such as splay on the surface finish which isn't acceptable in some applications, also welding of small joints becoming an issue depending on mold temperature. With pellet colored plastic you can start to see a difference in the color as it "burns" the color out with each additional heat cycle. I have never tried 30 times recycled but after 2 or 3 times recycled with styrene and abs it wasn't cost effective with our process as we only have one regrinder so it was a long job to clean out the regrinder between acetal and abs as mixing those cause toxic fumes when heated.
I would love to see you do this with the other types of plastic as well.
We certainly will!
1 You guys ARE the reliable source for plastic recycling!!! At l;east on a home/shop scale!!!
2 You need Need NEED to do a crossover with CNC Kitchen!!!
Amazing! Now i am really hyped to see how different kinds of plastics perform!
How about PET next?
Polyethylene is a pretty good durable recyclable plastic. Usually the process when being remolded is to add a percentage of virgin to the regrind to help with its integrity. However, if you’re running something like ABS or a stiffer or glass filled plastic, something that requires a hotter mold with thermolaters, or the machine temperature to be exceptionally high, that plastic can degenerate a lot quicker. There were times when we were running low on a plastic, and had to use 100% regrind to try to complete the order, but the resulting product caused more scrap than running it was worth. Depending on the plastic, you’d either get shorts, or it would get too viscous and flash out. It was a real crapshoot during those times.
Poly is usually forgiving, though, as long as it doesn’t get overly contaminated.
I work in a plastic factory and the two things that limit the recyclability of the plastic is degradation from heat which happens during melting and molding and degradation from time and weather, you can't really say that plastic can only be recycled a specific number of times
One thing we have to consider is that we recycle plastics that already have served its purpose
For example A Pot will be used in sunlight, rain and it greatly changes its strength and when we recycle it again , we use it again under the same conditions that results in a decrease in strength more and more.
But i highly appreciated your efforts ❤❤
Thank's for yet another great video 😅 you guys are true heroes 👍👍
I really like youtubers that annihilate misinformation in practice.
Most of the time, the problem is the use case and not that it can't be recycled, but how many times can it be recycled before it doesn't meet with their quality control, which can be for something simple like color, for example, Coca Cola was hesitant to use recycled HDPE because in their tests it wasn't completely transparent, but then they figured it out how to make it work (and with collection centers specific for PET it was easier because they are a lot cleaner so they don't need extra steps) so they now use recycled PET, which is great news, but yeah, it depends. For things that are not so picky in terms of color (for example if you use pantone), most plastics can be recycled many many times if you're careful not to overheat them
I think the reason its hard to put a number on how many times you can recycle them is the age of the plastic determines its degradation from oxidation, uv light etc
Incredibly interesting stuff, i had no idea it could be recycled this much. How i thought it always was in textbooks was 30-40% new plastic was introduced in each cycle and the oldest stuff was thrown away
This comes down to the different properties of different plastics, their volatilities and how they react to heat. A large chunk of plastics aren't actually plastic injections, but rather resin casts and resin is entirely impossible to recycle. it can only be shredded and burned. Different kinds of injected plastics, like you use here, have different heat tolerances and baking preferences; some ask to be baked for long periods and others not, however, so long as material is not lost they are theoretically infinitely recyclable for the exact same reason why metals can be recycled indefinitely and it's for a few key points:
Let's start with environmental damage. These plastics don't have the same level of volatility, eg, they're more stable compounds and as a result, are very resistant to UV, water, etc., damaging them. They don't rot, and remain for the most part static. A piece of plastic like this could have been sitting out in the elements for decades, and be in the same condition it was when first cast. This is not the case for plastics created from resins, like PVC, polyethylene, epoxy, etc., which all degrade rapidly when exposed to UV light (they turn yellow and brittle.) These are by far the most commonly used plastics, for example many vehicles outer shells are created entirely from this, headlight lenses are made from this, fibreglass is universally made from this, etc., and they're used because they are sturdy, light and resistant against physical damage and deformation. They usually have a high ignition point, and can handle lots of pressure and heat before degrading. This is not the case for plastics used here, which will melt when exposed to high heats. They're also, rather importantly, food safe as they do not contain any catylists such as polystyrene, which is used almost universally in other plastics like polyethylene or, the plastic named for it, styrofoam.
To summarize, the plastic used here is infinitely recyclable, so long as it's cleaned and treated properly; usually with some chemicals and lots of water. Resin-based plastics, formed by chemical reactions, are entirely unrecyclable. That's why every single plastic object should have a label saying what kind of plastic it is, and whether it's recyclable (though I'd prefer it be banned entirely and we go back to good old glass).
it’s crazy that i found this video as i JUST started working for p&g and something they really hold true to is high quality products!
I've done a lot of work with plastics in a former job and I can definitely say that HDPE is one of the most recyclable plastics you can run across. PP definitely will give you different results if you try it out. Honestly, it surprised me how different plastics can be.
Another thing that can help your search into recylability is to look up a term called re-grind. It is an industry term for including shredded waste parts with virgin material in making parts.
would love a video like this in other kinds of plastic
I thoroughly enjoyed watching this
Hey, it's super cool, and maybe we could put these recyvled plastics into those bits that get used in buildings like the plastic casings for screw we use when attaching picture frames or other built in bits...
If you repeat this experiment, you should use a strain gauge tester to get some quantifiable numbers on the force needed to break them.
Probably the fragility of a given design is probably just as important. Something with real tiny fiddly bits to snap and such would probably be better for "fresh" plastic just to be safe, whereas stuff with no moving parts at all you can probably be way more willy nilly with the usage. At the end of the day, if it's something important enough to matter, it probably deserves its own set of tests.
Would love to see more testing like this! Maybe more quantified testing with some sort of strain gauge setup a la CNC Kitchen to get some concrete data?
Nice test on that, and on really brittle and mixed plastics better ways to break it back down into oils should be researched. The biggest problem with that is energy as it takes a lot of heat and pressure to do that but in the end it would still be better than just letting it rot in landfills or the ocean.
the problem with putting a number on the amount of times something is recycled is that they limit it to being the same product that remains within acceptable margins of quality. I absolutely hate that they choose not to publish the possibility or transitioning to products with increasingly more lax margins. Just because some plastic is no longer good for a water bottle or carabiner why can't they just make starter plant pots or packaging or those little pedestals for holding rebar 3 inches off the ground or components that aren't seen anywhere like the underside of electronics buttons or the bulk of the inside of tools like a mallet or screwdriver or the little wheels under furniture that aren't good for ten years anyways or even lastly asphalt or pavers or just general aggregate or filler. Also worth noting that when a company says 5% recycled material it usually means they reuse the rejected products and or the little tabs that get cut off a molded part like the injection point.
Thanks for the info fellas! 😃👍🏼👍🏼👊🏼👊🏼
Thanks for watching, Fred!
Well done guys!
This was a really cool video. Thanks for making it.
Really glad you enjoyed it!
Please test any plastic you can. This is fantastic info.
Thank you! We will ♻️🙌🏼
You got these results, definitely because of the type of plastic you used. HDPE, LDPE, and Polypropylene will give you these type results, although the polypro will show degradation more than the High and Low density Polyethylene. If you want to show degradation as it would be in another application, use something like polycarbonate, or acrylic. Those acrystaline plastics show degrade through heat quicker than an amorphous compound like PP or HDPE.
This great. Super informative
I've always been curious what would happen if you added some propylene glycol. I've added it to soap to make it easier to melt. I know plastic and soap are WAY different. I'd be curious if it helped flow or soften the plastic. Just food for thought. I love the channel.
I don't think propylene glycol should be added to HDPE, I think it will just weaken it immediately because propylenes and ethylenes are not miscible in each other. Try ethylene glycol instead.
But yeah worth an experiment because I don't really know for certain.
Beware of long term effects. Both can help plastic draw humidity from the air and might act as plastifiers. But the water can then be catalysed by UV light and heat to perform hydrolysis on the plastic, causing it to fail sooner in use. How susceptible plastic is to this, varies a lot, and I don't know the details. Many plastics derive strength specifically from absorbing water into the matrix though, nylon being a prime example but this can also be observed with some others.
I think ultimately this is why it's great for soap, because it's a water based product essentially, just mostly dehydrated. And PG helps it hold onto a little bit of water, not too much not too little. Also it's pretty remarkably safe, MEG less so.
@@SianaGearz You definitely understand the principles behind it better than I do. But I'm glad you could see my point and improve upon it.
@@SianaGearzso essentially what I hear you saying is that we can make millions of gumby toys! In all seriousness, thanks for sharing!
To add to this discussion: while the degradation in the case of this material and this specimen is limited, an important point (at least in case of PET and recycled bottles) is that the reused material loses it's work-ability - reaching the same wall thickness in a hot-blow operation (e.g.: bottles) is impossible after 2-3 cycles due to the shortening of the polymer chains, and as noted: contamination is the killer when it comes to plastics, not to mention the mixing of degradable plastics into the same container as the "non-degradable" versions...
Hey, brothers! This is great research. Thank you and your team so much!
I felt very uncomfortable seeing you bend it that first time. I just didn't want it to go to waste. I'm so impressed.
SUGGESTION
Recycle fabric bags into plastic pellets or whatever! I think that shredding fabric is challenging.
Thanks so much, Eugene! Haha, we did as well - but don't worry, we had planned on recycling them back down, but it turns out there's no need.
Good idea, we've yet to venture into fabrics!
@@BrothersMakeThat's great to know!
By the way, the thumbnail is great, because it didn't give away the results, while still conveying the main topic and expectations..
Ah that's awesome to hear, thanks bud!
First time seeing your channel, amazing work! Sorry if this question has been asked/is answered in another video but do you/have you considered making 3D printing filament as one of the items you recycle?
Ha! A couple of years ago, I left a comment on a Brothers Make post about this exact topic. I’m going to lie to myself that that’s what inspired this video 😊
You forgot to do the most important part. This plastic is all from the same batch and doesn't mimic real world recycling. In real world recycling, the plastic is all from different batches each round. That's where the weakness is introduced.
This is the key point we were trying to make at the end - that weaknesses are introduced when different types of plastics are incorporated. But if the time is taken to clean and separate into plastic types, then it will be fine as long as 100% HDPE is used (for example. You can see at the end where we cut the 30x blue recycled plastic with the 1x white recycled plastic - the result is perfect ♻️