HOW STRONG is PET Bottle Filament?

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These parts have been 3D printed with filament  made directly from old PET bottles. Is this only   a gimmick, or is this recycled filament something  that could be really useful? I didn’t only print   pretty parts with this exciting material but also  tested how strong it is! Let’s find out more!   Guten Tag everybody, I’m Stefan  and welcome to CNC Kitchen.  A part of this video is sponsored by NordVPN.  More on them at the end of the video!  PET bottles are something I’m sure all of us  have at our homes. But did you know that you can   quite simply recycle one of these bottles into  usable filament without the need for complicated   and expensive shredders and extrusion systems?  Pull-trusion is a method that I’ve been hearing   more and more about of over the last year.  Pultrusion means that you take a PET bottle,   slice it into a long strip using a simple fixture  with a razor blade, and then just pull this tape   through a slightly modified 3D printer hotend  and get ready to use filament out of it!   This process got me pretty excited, and at  the end of summer last year, Joshua Tailor   sent me a beautiful package with some  samples made from different bottles. I   highly appreciate his input on this process and  permitting me to use some of his footage here.  I’m quite sure that I want to dig deeper into  this topic, but before I build myself a machine,   I thought it might be interesting to take  a closer look at the filament, how well   it really prints, and of course, how strong it is! Basically, all 3D printing filament nowadays   is made by extrusion. You feed plastic pellets  together with some pigments into a screw extruder   that melts and mixes everything, and then you  pull the molten material to the right diameter.   Equipment for this is pretty expensive and  something that’s hardly feasible for home users.   Pull-trusion simplifies this process quite a  bit because you just pull a piece of PET tape   through a cheap 3D printer nozzle and get filament  out of it. An average PET bottle has around 20g   of usable material, so it’s not a ton of filament  that you’re getting. The interesting part here is   that the nozzle is only heated to around 200°C,  which is below the material’s melting point   to just make it soft. The nozzle then simply  folds the soft material leaving you with a   really interestingly shaped strand of plastic. The  nozzles are usually drilled to 1.6 mm, but due to   the slight deformations after the shaping process,  the outer dimensions are within a range of 1.6 to   1.9 mm. There are some gaps in the cross-section,  so we will have to adjust our flow rate later.   I’ve first seen that process implemented in  Roman Naskashevs PetBot that you can get over   on Precious Plastics. The materials Joshua sent  me were exactly made on one of these machines.   The PetBot is a recycling station that features an  automatic bottle slicer and winder and next to it,   the pultrusion station. It is not cheap  with 235€ as a kit and 400€ assembled,   and since it’s shipped from Russia might come  with expensive shipping costs and import taxes.   That’s why I’m so stoked that Joshua developed  his recreator 3D, where he took a super cheap   3D printer and converted it with a bunch  of printed parts to a PET filament maker   that even combines slicing and pultrusion into  one step! Great concept! Honestly, you could even   build a working machine for only a couple of bucks  with just a hotend and pull the material manually.  Well, how does this oddly shaped filament print  then? Way easier than I thought. I used a standard   PETG profile, raised the nozzle temperature to  260°C, and set the bed to 80°C while turning   the fan to only 15%. Due to the difference in  diameter, I set the flow to 130%, which was   almost spot-on. I didn’t have a lot of material,  so the number and size of my prints were limited.   The Marvin printed in Fresca Grapefruit Citrus  looked great. Super details, nice extrusions,   and not a lot of stringing. The 3DBenchy also came  out beautiful. I had to switch materials in the   middle because the green mini spool ran out. Even  the transition between the material looks super   smooth, which shows that even though the filament  is oddly shaped, the surface area of the filament   and, therefore, the flow stays quite constant.  Even though I used only minimum cooling,   the overhangs look good, and even bridges printed  remarkable. Keep in mind this 3D Benchy used to be   half a Coke and half a Mountain Dew bottle.  How awesome is that?! I printed the material   on Prusas Textured PEI sheet and the OSEQ  PEI sheet and had no issues with warping or   adhesion! The parts, of course, have the same  color as the bottles came out shiny and nicely   translucent. So clear Coke bottles give you clear  prints, green Mountain Dew bottles, green prints.  I later increased the nozzle temperature to  265°C and reduced speeds to only around 30mm/s   because otherwise, the layers wouldn’t properly  bond together. My test hooks looked superb   and without any extrusion inconsistencies. The  lying tensile specimens were super transparent,   and the standing ones – wait, what – were white?!  Okay, so let’s talk about the reason why there is   sooo much PETG filament and barely any PET  filament on the market, even though this polymer   is way more used in other industries. Well,  one reason is that PET is a semi-crystalline   polymer which means that if you give the  material enough time at higher temperatures,   it will crystalize out, which is most obvious  from the change from transparent to opaque. This   crystallization process changes properties like  toughness, stiffness, density, or melting point   and makes the printing process more complex. The  material will even crystalize within your hotend   and if your temperatures are not high enough,  it will clog! The thin structures on the tensile   samples with the low amount of cooling stay hot  for quite a while and therefore gives the material   time to crystallize. This, of course, depends  on the shape of the part and the print settings.   PETG is the glycol-modified version of PET  which doesn’t only lower the melting point   of the material, but due to the more complex  polymer structure, it stays amorphous. And since   PETG has comparable properties, is printed much  colder, flows better, and is usually less brittle,   it’s just the way more suitable polymer for 3D  printing. But let’s test my small set of samples   and see how the recycled bottle PET performs in  terms of strength and compares to other materials!  I first started with the tensile samples that I  put into my DIY tensile tester one after the other   and loaded them until they failed. With 59 MPa  of failure load, they were definitely one of   the stronger materials I’ve tested so far and  different from PLA for example, they were really   ductile and didn’t break. Unfortunately, all  of the layer adhesion samples failed at the lug   which doesn’t give us real numbers about their  strength. If we omit that and just take a look   at the numbers, the layer adhesion is  seriously good with 31 MPa on average   and is probably even better if we get the settings  right. If we take a look at the rupture surface,   one side even looks as if it was injection molded  because there aren’t any layers or voids visible.   Of course, the part crystalized, so it would  probably be different on a normal part but   still impressive results. Next, I tested my hooks  representing a more realistic part and loading   scenario. The one printed lying failed at 67 kg,  making it the second strongest material I tested   here. Again, no sudden break but rather a slow  yielding. Layer adhesion on the standing hook   wasn’t impressive because the part failed at only  16 kg. There can be a lot of reasons for that,   but I just didn’t have enough material  to optimize the parameter at the moment.   I think, if we would further lower cooling and  increase the temperature, we might be able to   see similar results as with the standing tensile  samples. Lastly, I checked the impact strength of   lying samples with my impact tester. When the  hammer strikes the sample, the part absorbs   some kinetic energy. The more it absorbs, the  tougher it is and the lower the final position   of the hammer will be. The bottle PET samples were  not the most impact-resistant with 7.5 kJ/m² but   still landed before PLA and PETG. Again impressive  for being cheaply made from old bottles!  So there we have it. Honestly, I’m hugely  impressed by the print quality and performance of   this homemade, recycled PET filament. Of course,  working with 20 g pieces of material is a pain,   but maybe someone develops an easy DIY version  of something like the Palette Splice cores   to easily fuse the material because all other  splicing solutions I tried in the past are just   horrible! Another question is the economic and  ecologic feasibility of this method. Here in   Germany, we have a well-working bottle deposit  system where 94% of all PET bottles get recycled,   simply because there is a 25 cents deposit  on each bottle. 25 cents for maybe 20g of   material might sound expensive, but if you do the  math, that’s just a bit more than 12€ per kilo   for the raw material. Normal PETG filament sells  for around 30€ per kilo. And there are plenty of   countries with lower or even no deposit where you  could have access to free raw material. Of course,   all of this is not accounting for your time,  the initial invenstment and the energy used in   this process. I somehow see Pul-truding a bit like  stuffing your own cigarettes. It can be feasible   if you have the time; if you would otherwise work  a job, don’t even consider doing it yourself.   If you leave that out of the equation, this  process is way more than a gimmick and really   interesting for education to demonstrate perfect  recycling of otherwise discarded bottles. The   most interesting application for me are actually  countries and regions where people either don’t   have the money for buying filament or it’s simply  just not available. PET bottles are everywhere   and seem to make a great source for material  that’s strong and well usable in a wide range   of applications. Of course, you need a 3D printer  with an all-metal hotend and heated bed, but these   have become really affordable in the last few  years. What do you think? If you want to learn   more, check the resources and channels linked  below, especially the YouTube channel of Joshua   and this crazy Russian guy named Brother, who I,  unfortunately, can’t understand but he seems to   3D print everything and even made an extruder that  directly prints with these PET bottle strips! And   here’s the question for you. Do you think I should  build myself one of these recycling machines and   properly investigate use cases, feasibility, and  material properties? Leave a comment down below!  Oh hi! Well, did you know that  I’m currently on vacation.   Well, let’s rather say a virtual vacation because  did you know that NordVPN, not only protects your   internet traffic by encrypting it and covers your  IP address like this beenie covers my crazy hair?   It also let’s you change the country from which  others think your browsing from just by the   click of a button. 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It’s risk-free  with Nord’s 30-day money-back guarantee. That’s   nordvpn.com/cnckitchen, or click  the link in the description below.   Thanks to NordVPN for sponsoring this part of  the video! You can find me in, aaah Braizil now!  Thanks for watching, everyone! I hope you  found this investigation interesting! If   you want to support my work, consider becoming  a Patron or YouTube member and check out the   other videos in my library! I hope to see you  in the next one! Auf wiedersehen and goodbye!
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Channel: CNC Kitchen
Views: 909,802
Rating: undefined out of 5
Keywords: 3d printing, pet filament, 3d print, bottle cutter, how to, cnc kitchen, pet bot, petbot, pet recycling, recycling, plastic, bottle, diy, filament, plastic recycling, free filament, pet filament extruder, pet filament 3d printing, pet filament maker
Id: N06FWr06iOI
Channel Id: undefined
Length: 13min 59sec (839 seconds)
Published: Sat Jan 22 2022
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