Ocean plastic research
@cymek and I are working in the Precious Plastic & Parley shipping container in the Maldives til May.
While we’re here one of our focuses is learning about ocean plastic, particularly how the extended exposure to saltwater/UV/contamination affects its recyclability with the PP machines.
We’ll share our research below 🙂
Just had a thought…
Has anybody within the community done any traffic analysis on this plastic waste?
If only by ‘scanning’ the packages/waste and mapping where it’s coming from (per location…).
So not just collect and recycle: Record and report!
If most of your ocean/beach trash (plastic, not tourist) comes from X, and you can PROOF this, the UN would be very interested…
I know most of my trash (should I choose to waste my resources) would most likely end up on a certain beach on a certain dutch island, so I do keep it local, but this is mainly because, well, the Netherlands is (yes, a singular plural) an exeption to the rule (like being a singular plural).
Photooxidation is another degredation mechanism that is said to account for a lot of the effects of polymer ageing. In essence, the free radicals, exposed by breaks in the C-H bonds, latch on to atmospheric oxygen.
Materials affected in this way are said to have “perished”. This is predominantly a surface effect – so would tend not to affect the body of the material, unless surface microcracks allow atmospheric penetration (as can be seen on some elastomers that have been exposed to air and sunlight (eg. nitriles and natural rubber).
The above tests on HDPE indicate that if surface oxidation is happening, then it is only happening in the very outer layers of the material, and so it is negligible in volumetric terms. Hence the oxidised molecules are simply lost during remelting.
Shredding rope with the sieve installed works pretty well. A certain amount of rope builds up in the machine, but once it reaches a certain threshold, rope falls through the sieve rather than continually builds up. The only drawback is that some rope remains in the blades after shredding is finished, so you have to remove that by hand before shredding other types of plastic. It only takes a few minutes to do this so it’s not that bad.
Shredded rope feeds into the barrel more easily than long rope.
One issue with extruding the rope is that it’s much lighter than typical shredded plastic, so the screw pushes it forward in the hopper and then it builds up on the slope of the hopper instead of falling into the barrel. To prevent this, I prototyped a new hopper with vertical walls so that when the rope is pushed up against the wall, it tumbles backwards instead of building up.
So glad to see your progress in recycling ocean plastic! I’m about to get underway with recycling plastic in Hawaii and everyone I’ve been talking to is trying to get me to recycle ocean plastic. I’d been hesitant to start with ocean plastic due to the extra complexities, but after seeing this post, I’m reconsidering. What are your thoughts?
One type in particular that stood out to me was plastic textile commonly used on boats in the form of rope and tarp.
The thing about these materials that I find interesting is that they’re so ubiquitous in coastal communities (at least the ones I’ve visited), but when I speak with people about them, they’re usually surprised to find out that they’re made of plastic.
One issue that’s particularly problematic when it comes to plastic textiles, especially in the ocean, is the fact that they’re made up of such small fibers, which inevitably degrade and pollute the environment over time. Once they’ve degraded, they become much more challenging to manage.
To start, I collected a sample of plastic from the nearby beach. Every type you can imagine is there – thermoplastics, thermosets, textiles, old, new, micro, dirty, degraded.
Thank you Iris. We have now discovered that in fact one of the ropes we have are PolySteel which is a Polyolefin Copolymer which melts at 194 degrees C. We have been melting this thinking it was nylon and getting fumes at around 200 degrees. We have found this website which has help identify some ropes https://southernropes.com/ropeinfo
There are more I will send them later.
We were a bit silly thinking all ropes were nylon, and are being super carefull now. I am making a table with pictures, names, melting point etc. I will post this once I have completed it.
Fantastic information from all your tests that has been invaluable to me as I have just starting to look at ocean plastic waste that is local to me (north east coast of Scotland). I was struggling with what PP machine I should go with as limited funds and a small shed but after reading all your work and like you I am coming across loads of rope/netting or containers that are starting to break up have gone ahead and ordered the parts to build an extrusion machine.
Keep up the good work.
Great work from your group Joan, at present I am on my own but once I get going with my machine and gather more information on the plastic around the Aberdeenshire coast, I will give you a shout to see if we can help each other in some way.
The heat needed to be increased to 240 and 250 to get the material to melt properly, and once molten, it began rising in the barrel towards the hopper – not sure what caused this.
Injecting worked pretty well, it didn’t seem to flow as smoothly as the rope. An increase in temperature might help this.
Like the tarp, this material also began to rise in the barrel once heated – if anyone has any insight as to what’s causing that, it’d be greatly appreciated
I think it’s because of the different types of nylon. There are the common ones Nylon 6, Nylon 6/6 and Nylon 6/66. Nylon 6 has a 220 degrees melting point where Nylon 6/66 has a meltingpoint of 265 degrees. The rising could be caused by the chemicals added to the nylon to make it stronger so be carefull with inhaling the fumes 😉
you could read this for more info about nylon:
awesome project you are doing/did!!!
@suzereuse very interesting research – while using plastic as an alternative aggregate for concrete might give us somewhere to put the material for a few decades, i find myself wondering if ultimately it just complicates things. hopefully we can continue experiments to learn more about the viability of recycling UV degraded plastic 🙂
@joandarcy great work at the tippy top of Scotland! some resources on nylon fishing gear:
an Italian company Aquafil makes high-end designer wear and carpet from ocean nylon nets in a factory in Slovenia [ghost nets are usually nylon]:
they cater to upscale market because (I deduce) their product is more expensive than virgin nylon. That’s because nylon is hard to work with:
https://www.patagonia.com/recycled-nylon.html “For some reason locked deep in polymer chemistry, nylon is more difficult to recycle than polyester.”
“The economics of recycling nylon are not very appealing, however. Stephen Johnston, an associate professor in plastic engineering at the Univ of Massachusetts Lowell, ran a research program on recycled fishing nets for Bureo. Nylon, he says, is not an easy or cheap material to recycle. “
for those wanting to research nylon more, it is polyamide plastic and the most common form is PA6.
And if this waste washes up somewhere, in quantities, this can actually be proven and cut of at the source.
Making international dumping more trouble than it’s worth by outing these practices AND offering a local alternative (give US al your waste plastic) is actually something we could do.
The proof is in the pudding(packaging)!
Maybe it’s time for a reminder of this thread from last year:
And yes – a large portion of the waste plastic being inadvertently pushed into rivers, during informal manual sorting/scavenging in underdeveloped countries, has come from Europe and North America.
Makes you wonder what happens to the plastic waste the world exports to southeast Asia for recycling that does not have enough value.
Thanks for the link.
If more local initiatives would do similar tracing, we could really build some momentum.
Gapminder might be a good tool for this (for origin and landing stats of the plastic waste).
I’m afraid ‘1 beach’ will be considered a local issue, but let’s see it as the first step. A global network of data is harder to ignore (even ‘Europe’ only would be a local issue).
I’ll reach out to my EU contacts for more info to find an ‘in’ at he UN (open invitation, PM me if you (somebody) already has more information).
Do you have a spreadsheet you could share?
I’ll try to formulate a simple data structure for collecting data, so anybody can join in. You can help me determine if collecting such data is feasible.
Indeed, if only all data was this obvious!
But even EANs (barcodes) can give valuable information and would be easy to trace as often they are also region bound (there is an international database).
Or languages of the ingredients, or…
to be continued…
@pauldufour , As before great work. The results for the degraded plastic (HDPE?) are very encouraging. I’ve been trying to figure out what to do with crumbly flower pots, etc.
Were the samples on the display board injected? Are those temperatures the body temperatures or the nozzle?
You’ve posted a lot of great results, are you planning on collecting them (along with some detail) in a report of some form?
Thanks again for the update.
Before leaving I wanted to make something useful out of the recycled ocean rope to show that it can have practical applications.
We built this side table (and sometimes foot rest) to put next to the Jolly (sp?) chairs in the hangout space.
@joandarcy thank you for posting. The work that you and Paul are doing in dealing with poor quality ocean trash is inspiring. Especially your work with Nylon. I saw the article https://news.nationalgeographic.com/2018/03/great-pacific-garbage-patch-plastics-environment/ where it was reported that 46% of the great garbage patch in the Pacific is fishing nets. Now if there was an effective way to collect it.
Nice work guys! keep it up 😀
Sample of foams and foils pictured below:
Sample of thermoplastics, marine textile, and thermoset pictured below:
This is a great thread and thanks to everybody who contributed.
I am trying to recycle used fishing nets taken from the Atlantic around Ireland. So far I’ve tested what I think is PP and nylon netting. I’m using an injection machine and moulds that I bought from Plasticpreneur.
I manually cut up the nylon net with a scissors. I had to heat it to about 250 to get it to melt properly. There were some dodgy smelling fumes so I kept the injection machine outside.
Once heated the plastic flowed smoothly. I didn’t cut net to make a small pot so it’s only half completed. This was down to the quantity of material I used rather than anything else. The finished material was described as “seaweed green” which was very different to how the net originally looked.
It was incredibly difficult to get the pot out of the mould. I ended up using a hot air gun to reheat the plastic.
I’ve attached pics. There are a lot of nets being gathered around Ireland that need a proper solution.
The V4 team is starting to look at the fume issue here http://onearmy.world/community/forums/topic/v4-fume-extraction-4/ . I added a fume hood to my version of an injection machine here http://onearmy.world/community/forums/topic/portable-desktop-injection-machine/page/3/ .
Depending on which machine you have or are planning to build, it can be easy or more difficult. Building it on wheels so you can roll it outside helps as well.
@joandarcy fumes are certainly something to be mindful of – my most simple recommendations would be to do experiments to see what the lowest possible melting temp for the rope is in your oven and use that.
if fumes are still an issue, a respiration mask will filter out most of the VOCs being released in the process.
@irismongolia is a chemical engineer on the V4 team working specifically with fumes – I’m sure she’d also be able to provide some insight (and maybe double check that i recommended the correct mask 😉 ) hope this helps.
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