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I’ve been working on the development of the sheet press mould with @renacerixlizard for the past couple of weeks and wanted to share what we’ve experienced so far.
We’ve experienced a few small problems which, when combined, compounded and resulted in mould failure.
– Airline valve malfunction
– Jack valves were accidentally left open due to valve closure mechanism malfunction
– Both of these issues resulted in reduced pressure while pressing sheets
– Reduced pressure led to sheet not being cut from excess plastic
Since the cutting strips didn’t separate the sheet from the excess plastic, the excess plastic pulled inward against the cutting strips when cooling/shrinking, creating small gaps between the individual components of the cutting strip.
Similar to the effect of water freezing in cracks of a sidewalk, the gaps grew larger with each press.
With the current mould, the cutting strips are screwed together so they can be disassembled. The plastic eventually pulled enough to remove the strips and screws from the bar altogether.
To prevent this from happening again, we welded the strips together instead of using screws. It helped, but still the plastic was able to pull the bar inward where it wasn’t welded if enough pressure wasn’t applied to separate the excess from the sheet.
Plastic also entered the gap between the strip and the sidewall, pulling the entire strip inward, compromising the screws which hold the assembly in place.
It seems that the most straightforward solution to this problem (without completely changing the mould design) is to weld the parts together so that there are no open seams where the plastic can flow. We’ll see how the mould handles the forces if the plastic isn’t cut properly. It’s a lot of welding, but if it makes the mould more robust and long-lasting, it might be worth it.
Our plan moving forward is to weld the strips together, then weld them to the sidewalls so that there are no open gaps. The bottom sheet will then be screwed into the strips the same way it is now, possibly with a second row of screws.
Some tradeoffs in this development are:
– No longer able to fully disassemble cutting strips, but bottom sheet will still be removable
– More welding during mold build, but less thread tapping (which was potentially more of a hassle)
If it works, this development will prevent mould failure from happening in the case of sheet press malfunction. We’ll let you know how it goes.
As we built out the space, we designed it so that it could be set up and torn down easily each day.
We used this quick release method for all of the hanging objects (chairs, planters, light fixtures).
Suspending objects (specifically chairs) also reduced the amount of space they took up when stored since they didn’t need frames/legs.
Lattice, planters, light fixtures and hanging storage for plants when space is closed
Display table – functioned as centerpiece to showcase smaller PP creations
Joalie Chair with Coconut Rope
In the end we created a collection of objects which functioned as a space for visitors to hang out where they could experience the possibilities a Precious Plastic workspace offers firsthand. Below are some images of our work.
@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 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.
To share what we learned, I made this display board showing the results of recycling plastic waste that people might not typically think of as a “recyclable”. It’s hanging in the workspace next to the injector.
More extensive testing should be done to get a better understanding of how UV degradation affects the properties of plastic, but from this initial test it seems that degraded plastic, once recycled, is still quite strong.
We used a hydraulic press to test the beams’ flexibility and compression strength.
We applied 12,000 metric tons of force and there didn’t seem to be a substantial difference between the behavior of the beams. Perhaps I was wrong in my previous research (https://davehakkens.nl/community/forums/topic/non-recyclable-plastic-waste-v4-2/)
Then we extruded them into beams to test their strength. The degraded beam’s color was a bit less saturated than the new one, but aside from that they felt pretty similar.
Experiment 06 – Testing Effects of Ultraviolet Degradation
<span style=”color: #313131;”>In addition to experimenting with marine textiles, I wanted to get a better understanding of how ultraviolet degradation (common in ocean plastics) affected the material properties of plastic after it’s recycled.
</span>All over the island there were loads of these yellow bottles in varying degrees of degradation, so I used them as a control for the experiment.
To start, we shredded a good-as-new bottle and the most degraded bottle I could find to compare properties of the most extreme types. The degraded bottle was considerably weaker than the new one – you could tear it apart by hand without much effort.
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.
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.
And here’s a clearer pic of the two hammock (Jolie) chairs
Along with the hammock chairs, I built a bench using square tube, angle, and extruded plastic beams.
As the “hangout area” has grown, more and more workers have been spending time at the workspace watching us work and enjoying the furniture. It’s been cool to see that building the hang out space is actually helping attract people over to the container to see what’s going on.
Managers of the waste management company, some of whom started out skeptical of what we could do here with PP, got excited about the bench and asked us to make more 🙂
Experiment 05.2 – Swapping the extrusion screw for the old auger
The spacing in the extrusion screw is considerably smaller than that of the old auger we used previously, so I decided to reinstall the auger to see if the larger spacing would make it easier for the rope to load into the machine.
Our shredder broke down (extra strong motor sheared shaft, not during rope shredding) so I’ve only been able to experiment with hand-cut, unshredded rope so far. The results have been promising though – the larger gaps in the auger help considerably and I was able to make a second beam.
The screw was spinning at a low RPM in the beginning, so the beam didn’t fully form, but once I bumped it up to full speed it worked quite well.
I was curious about how big of a difference cleaning the rope actually made, so I used dirty rope for this experiment. As you can see, a simple clean with a quick rinse in a tub helps quite a bit with removing the sand, dirt, etc.
Once our shredder is working again, I’ll test the auger with shredded rope.
That said, I was able to successfully make a short beam using the shredded rope 🙂
Experiment 05.1 – Shredding ocean rope
To see if it’d be easier to feed into the extruder, I shredded the rope before extruding.
Shredding the rope worked pretty well, but since the rope fibers are so thin, they began to heat up and clump together a bit as the machine warmed up.
Feeding the shredded rope into the extruder was better, but still not great. The material is very light, so when it’s clumped together it sometimes sits above the screw gaps instead of falling in, meaning it still needed to sometimes be coaxed in by hand.
Experiment 05 – Extruding ocean rope
Seeing the success of the ocean rope with the injection machine, I wanted to see if we could manage to feed it into the extruder for easier processing.
First I experimented with cut, but unshredded rope. It worked, but it was hard to feed it into the machine at a consistent rate – sometimes the extrusion screw took the material without trouble, but other times it had to be coaxed by hand.
It did work though, so now it’s a matter of figuring out the best way to feed it into the machine.
Experiment 04 – Transport bag
Another item that’s commonly found degrading are these transport bags.
I ran the same experiment as the others and found that this material can also be recycled using the injection machine.
These bags are made up of a few different components (bag, straps, threading) so I’m curious to see if they can all be recycled together or if they need to be separated.