Melting temperature tests
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There are different types of plastic and each plastic has its own melting temperature. You can easily find this online. However there is a big difference between the melting range between different temperatures, does it get liquid when it melts and what if you burn it? There a re a lot of stages the material can be molded. We want to visualise this. Making it easier to understand the behaviors of plastic on a specific temperature.
Plan: Make a few simple molds which will be filled with 50 Gram of Plastic(from different types) They will be heated for 40 minutes at different temperatures to see how it behaves
Took a bit before I figured out a consistent workflow i can keep repeating. I need this to make sure its only the temperature that changes, and nothing else. Got a good routine, now lets start melting
This turns out the be more works than expected. But keen on getting it done, very interesting to see the behaviours of the different types
Finished all the experiments from 130 to 260 degrees. Useful that its a very clear overview of the different properties at certain temperatures. Next will turn it into a document which is easy to share with you guys. Hopefully it will be useful for others!
Dave,
What would you say is the best temperature to make PET malleable?
My senior design team is making a similar, automated machine, to recycle from home.
Thanks
Depends a little bit what kind of technique/machine you are using. The metling temperature is around 260 degrees. However compared to others types of plastic with PET this is very crucial. Couple of degrees above or below make it unnamable –is that a word? You got a picture of your machine?
hi Dave, how long does it take to melt once temperature is set? how to know once it has melted and can turn off the oven.
The link above is dead^
Has the document been created yet? I am currently struggling to find useful information on these in general.
Does melting plastic emit toxic gases or something? Or only when melted at a certain temperature? Does this add to our carbon footprint
@putripewe, here is the link to Download the files – the table is in the last folder “5. Create” 🙂
I am interesting in this question.
Does melting plastic emit toxic gases or something? Or only when melted at a certain temperature?
Could somebody answer please? Thank you!!
ditto! feel like this information is probably easily available for people who understand these things, but for someone with no chemistry background, i don’t even know where to look to get answers!
also interested in this… ‘bump’ 🙂
if anyone knows where we can get information about this, be a dear and post a link pretty please!
Does melting plastic emit toxic gases or something? Or only when melted at a certain temperature?
Dave:
I have considerable experience with extrusion of incompatible plastics (polymers), such as where certain plastics are difficult to sort out. Ideally you want to combine polymers than have similar polarity, from a chemistry standpoint. But that’s not always possible.
Certain polymers are not compatible under ordinary circumstances, so we use “coupling agents” or compatibilizers. Some of the more popular are maleic anhydride (MA), titanium/zirconium chemistry such as Ken React, and ethylenevinyl acetate (EVA) often with glycidylmethacrylate / butyl acrylate such as DuPont Elvaloy 4170.
I favor Ken React CAPOW by Kenrich, typically used at less than 1% by weight. Really ugly incompatibilities might use up to 2% Ken React. We mix it up a suspension in alcohol (keep shaking it) and spray it over the mixed plastic grind, tumbling it to get a more even mix, then feed it into the extruder. A bit lower temperatures than normal and a bit more torque work best. Some characterize this process as “Reactive Extrusion”, since a chemical / physical reaction is taking placing under high torque shear stress and heat.
I’ll post a polymer polarity chart for all.
Looking back that chart might be a bit confusing to some as it includes plasticizers (chemistry to soften plastics generally).
So I deleted the plasticizers to make it simplier. Here’s the new chart:
@basman @geezergarage
oh yeah, true! Here’s the most recent one: https://preciousplastic.com/en/videos/download.html
Have fun! 😉
Hi all:
I am struggling to understand the message of @blueholediver. Thank you very much for the chart by the way. But honestly, don´t get the use of “coupling agents”! jeje
In my case, I am just starting and while structuring the plan, I am searching about the use of plastic weathered by sun and sea water because I would like to reintegrate some of the debris found at beaches and the sea.
I understand that plastics already very weathered would be difficult to clasify by types, so the temperture would be also no determined. Apart of that obstacle, somebody knows about the loss of properties among plastics while weathering and some alternatives to reuse them?
Thank you,
hi Dave, thanks for this wonderful project.
What do you know about the temperatures and speeds appropriate for the filament extrusion for 3d printers?
thank you very much again.
This is wonderful, however I’m having trouble interpreting the results.
It seems that once the temperature is sufficiently above the melting temp, the inside is too runny and oozes out when laid on its side, rather than keeping its shape.
I suppose the goal, in order to conserve energy (and $$), is to use a temperature that is minimally sufficient to melt the plastic completely. However, especially in compression molding of larger parts, air pockets are a risk.
So, my question is: is there any problem with melting plastic above its melting temperature in order to make it less viscous, so long as you don’t burn the plastic?
To be specific, HDPE seems to form a smooth block around 150. Is there any harm in going to, say, 170?
A side note: a document in the Precious Plastic Kit lists HDPE’s melting temp from 130-137, and PP at 168-175. But those temperatures seem too low when looking at these visuals – again, HDPE seems better around 150 and PP at 190.
Given this, I suppose the best practice is to just use this as a guideline and then experiment with each plastic that we have to find what works for our process?
@davehakkens is it okay if i will use mixed types of plastic for compression molding? do you have any records about doing a test on that? thank you!
You wont know until you try…
We gotta get better at documenting this stuff, the actual experiments, not some calculator for polymers and bonding agents and any of that gobbledygook, love the photo of the grid of results, need to do that for failure testing for I beams and whatever else that is easily extruded… The different methods need to be tested as well, extrusion vs heat compression etc. 🙂 so much work to do
If I had to guess, I’d say the red block closest to the camera in that last photo would be the strongest of them all… highest temperature and it maintained it’s form when the others liquefied… perhaps that intuition is wrong? The longer it’s in the oven, the more energy it absorbs, the stronger it will be?
davehakkens
did you ever make that document? I’d love to see what you came up with
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