pet cola bottles..filastruder. YES!!!

Hello
I am trying to create PET filament from PET bottles after consumption, I have had very similar results to yours, with extrusion temperatures that vary from 235 to 245ºC, the problem I have is that when I reduce the extrusion temperature a lot, the filament crystallizes as soon as it exits the extruder die, while when the temperature is higher the low viscosity of the PET causes the diameter of the filament to be reduced to the point where the resin thread is cut, have you managed to solve this problem? How did you do it ?, I also have the same problem with the feeding of flakes of PET since they get stuck in the exit of the hopper avoiding the natural flow of the flakes to the barrel, sieve twice my samples, one with a mesh screen Nº5 (4mm) and one of mesh nº8 (2mm), neither one of the two granulometries gave me satisfactory results, I am using the horizontal hopper that comes with the filastruder with half a bottle of coca cola of 3 liters

thank you for the reply and input..coolio986

Your suggestion would yield beter results when the actuall temperature should be more constant and let airflow not cause the temperature drop so it will not eventually "clog" the nozzle.
I must say i have my compleet nozzle wrapped in fiberglass sheets/cloth you normally use for boots and epoxy resin to fix boots...
i folded a square piece like 3 times in half so i end up with a piece i could wrap on my nozzle but before that i did some sewing to keep the folded piece folded . then i used allot of super glue on the spot ( folded fiberglas sheet) where i would wrap my nozzle in. And then i drilled a whole in that spot of the sheet to let the filament  go through it. That seemed to really help to stabilize the temps.
I hope you can imagine how i made it , other wise i have to make some pictures
Any more suggestions are very helpful.

It is important to note that when PET crystallizes it forms a cloudy opaque appearance since crystals have grown. When it is clear it is in its amorphous state.

https://www.ptonline.com/knowledgecente … rphous-pet

I did forget to leave that part of the water temp out, sorry about that. The water temp I use is about 50c. It is this hot for a few reasons:

1. It allows the filament to cool slightly slower and more evenly since it is not being "shocked" to cold.
2. It allows the filament to maintain some flexibility before it exits the water.

The idea is to cool the filament to the point that it stays clear (amorphous) but slightly flexible at water exit. This allows the filament to refrain from snaking as you try to spool it.

Another thing that is a point of discussion is the length of the water bath engagement. When I run (2kg / hour) (oh it is not a filastruder machine) the water bath engagement needs to be about 600mm long. But for slower extrusions it doesn't need to be as long. I don't have any science to explain the minimum length of engagement, but I would guess it to be (for the filastruder) about 50mm - 75mm at 50c.

I also do not use water circulation as the circulation creates inconsistencies in the final diameter. The filament moving through the water creates enough disturbance to circulate the water on its own.

As for drying PET. Typically semi crystalline resins need airflow (and pressure) to form enough movement to allow proper drying. PLA isn't so picky, but PET is. The basic idea of proper drying is to reach a temperature (if using only hot air) that forces the water to expel from resin, but to stay just below the agglomeration point.

https://www.ptonline.com/articles/why-a … eed-to-dry

If you are using something other than hot air (like a dual bed desiccant dryer) than you can use low temperatures to dry.

As for the viscosity, I can't say I've heard anything related to drying temperature and viscosity. There are a few things that can affect viscosity during extrusion, one mainly being how wet the resin is. If the resin has any type of moisture in it, hydrolysis will form and break down the polymer chains and cause the viscosity to appear more watery.

If properly dried, the resin will adhere to the MFR/MFI specifications set fourth by the manufacturer. And since viscosity has a huge impact on MFR, I would tend to believe the datasheet.

http://article.sciencepublishinggroup.c … 401.13.pdf

It looks like you are on the right track.

Boiling water would help get the temp up, but not maintain it

I use this to heat my water initially: https://www.amazon.com/gp/product/B01M0 … &psc=1

But I'm extruding at such a high rate that the water stays hot from the filament passing through it.

This can be used to maintain your temp: https://www.amazon.com/Inkbird-Thermost … amp;sr=1-9

My water temp is about 50c, but with PET you have to be careful to cool it properly. If it is cooled too fast, the outer skin of the filament gets hard and the inside stays liquid (bad). If it is cooled too slowly it will anneal and turn crystalline (also bad). The trick is to find a balance between hot and cool. Cool enough to prevent crystallization, but hot enough to let it flex in the water to spool it (the 90 degree bend from the nozzle to pulling out of the water).

As for that hydrolyzed area, that's really bad. It also looks like decomposition of the PET as well which causes all kinds of problems. Usually when PET degrades it plugs nozzles and filters so be careful.

It is hard to tell from the picture, but the water level should be right up to the nozzle, at the top most part of your container. It should be 1-2mm from the nozzle but not touching.

Look like your well on your way!!

Very nice work!

You are making leaps on progress.

For drying PET you can use a high temp than 104c. 18 hours is a very long time to try PET, and if you increase the temp to 140-150c it will only take 6-8 hours.

It is normal for PET to crystallize when drying.

One idea for storing PET is to "dry" a bottle with the flakes, then store the flakes in the bottle.

Drying the bottle and the flakes will create a dry atmosphere in the bottle and should be safe for months of storage.

Another way to store any polar plastic (PLA, ABS, PET, PETG, PC, etc) is to use a non polar plastic container, like HDPE.

HDPE is non polar and doesn't absorb water, so you store for a very long time.

The stilson key (pipe wrench) is almost the same thing that I do!

I use 80/20 aluminium extrusion instead (so it doesn't rust) and I use a 1 meter long water bath to cool filament and spool.

I also run 4kg/hour so a bit faster

I enjoy the pictures, keep them coming!

Hello
I am very sorry for not writing for so long but I have had several problems and the truth is that I have not progressed as much as I would like,
First of all I made a mistake, the extrusion temperature is 245 ° C, however I have extruded at 245, 350 and 260 with successful experiences, of course at higher temperature lower viscosity which can be a problem when trying to get a decent diameter. however in that range I had no problems,
The main problems I have now is the filament guide and the winding of this one,
I have managed to obtain a 1.75mm amorphous PET filament but I have not been able to wind it, because when I try to place the filament in the filawinder, two things happen
1.- the filament tends to twist when I take it, the crooked sides do not enter the filawinder's plastic tube and I must start all over again
2.- the filament thins too much with the filawinder, it is really difficult to define an optimal speed so that the diameter of the PET filament is adequate and does not lose much weight,

I still can't find a way to use the photosensor to control this variable, the problem is that to obtain PET without crystallizing it is necessary that the extruder die is too close to the water, which does not leave room to place the photosensors

Regarding your questions, MAZHIVE
the nozzles are the stock, probe with a 1.75mm and a 3mm stainless steel
 I really don't know how to obtain the extrusion speed, with respect to the voltage, I just know that I change my power source to a 15V and 5A, now I don't know what the number that delivers the stall protection means, but if it is the consumption can i give you that information

I will do my best to solve these problems and have favorable results, thank you very much for your feedback and as always attached images of the experiences

drying temperature, try to set the oven at 160 ° C to reduce residence times but it was impossible, it is a very old oven, at that temperature usually dry 24 hours
the new configuration of the filastruder, at 45 degrees greatly improves the feed to the worm and reduces the number of times the filament sticks to the nozzle
filastruder extrusion temperature
PET being fed into the hopper, the bottleneck effect does not practically occur, although I would like to add a vibration device to it to flow even better, I do not know if you know of any device and arrangement of this in the hopper for that purpose
PET if any type of very fine cooling, I had already noticed before and if you let cool very thin PET filament it does not crystallize, of course it is not usable for 3D printing, but it looked so good falling that I dropped a lot hahahahaha
a lot of that super thin filament
filament that if it has the necessary 1.75mm for printing, amorphous but very short, this was the result of simply dropping the PET in the cooling tub, many curves were produced and the size is also very short, in addition to the ends crystallized

464/5000
and this is what happens if you try to extrude PET powder, it is really a disaster, it sticks everywhere and does not melt at normal temperature, cover the nozzle and activate the stall protection, I spent 2 days cleaning that disaster, so that it doesn't happen to them, it was PET with a diameter smaller than 2.38mm, I don't know what the limit size of the PET flakes is before that problem occurs, I just put all the leftover PET that I screened with an N8 sieve, and that happened LOL

Hello everyone
Thank you very much mazhive for sharing your work, eventually I have to get to a more stable format to use the filastruder, my fan also attracts my attention, is it quite large, does it heat the air it uses to cool the filament? It is an excellent idea if you ask me, I would like to know if it served you
On the other hand I have been trying to reach a diameter more or less similar to 1.75mm, now I am at 1.54mm what I think is a great breakthrough, I definitely gave up on the photosensors of the filawinder, it did not occur to me how could they be willing to fulfill their mission,
So what I did was to place the filastruder of a rice cooker very close (I don't know if a rice cooker meant anything to you, this text is being translated by google translator so I hope it is understood, anyway I will attach images) and drop the filament in very hot water, when you pass 60ºC (between 67 and 140ºC according to a paper I read about PET, Well it was a review actually) PET enters a state of glass transition where it becomes very malleable and manipulable for what it was perfect for the filament to fall and turn naturally just like the 0.8mm PET that I climbed the other day, to roll it up is as simple as leaving the PET immersed in hot water so that it enters the glass transition state and introduces it into the Filawinder tube, this will give the shape and being malleable PET, no matter what curves it has given this funky (it is important that the angle of the PET when it falls is not very closed since that section is ra thinner and more fragile than the rest, that is the purpose of letting it fall in water at a temperature above the glass transition temperature of PET)
Now if PET is left at this temperature for a long time, it will begin to acquire a whitish shade, I assume that they are small PET crystals that grow inside the filament to such a size that they are able to collide with the photons what gives that tone, but not big enough to completely crystallize and become brittle
It is also important that the newly melted PET does not float and touch another little PET that is going down, this section will merge and ruin our filament
Well, I think I'm really close to getting it, unfortunately the thermocouple reading becomes very erratic, I must isolate it with Kapton tape to avoid that error
That's all, less and less to get the long-awaited impression with 100% PET bottles
As always attached images of the experiences


The PET towers that I made, these allowed me to elucidate in what diameter the PET becomes semicrystalline and then crystalline, I could notice that at 0.8mm you will have amorphous filament without the need of any cooling mechanism, at 0.9mm it becomes semicrystalline and 1mm onwards becomes very crystalline

The first experience of PET falling to the rice cooker, the PET did not crystallize but it got enriched because the water boiled in that inntestant and produced a lot of turbulence

PET being rolled at high temperature, PET did not exert very little resistance to being rolled, its texture was like that of a cooked noodle, and the filastruder was like a man sipping the noodle, hahaha

Another image of the PET being rolled, it is important that the filastruder tube was submerged since at the time of the PET let the hot water harden immediately, the tube under the water gives it the straight shape that we want

Here another image of the PET winding, this one did much better than the previous one because it no longer floated due to the surface tension of the water, this I achieved by adding detergent to the water

a lot of 1,54mm PET filament, it must be a record, however something white turns around, it happens if I left it a long time under water, I must devise a way to remove the PET so that it does not happen
Well, I thank you all for your invaluable help, also to Tim Elmore, who also gave me some tips internally, we will see if it can be printed and if I achieve it, well I feel that it would not be just an achievement of mine but of all of us, as he said sir isaac newton, If I have seen further it is by standing on the shoulders of Giants

Well done! Very cool to see your progress, thanks for the details and photos.