This is probably going to sound silly, but having just stated building an extruder, and a shredder, I’ve been given a MASSIVE batch of ikea own brand Hama Beads (PYSSLA if you want to look). Basically, I contacted local business’s saying I was starting a plastic recycling project, with a link to the machines here that I was making, and asked if they could support me, and Ikea sent me a batch of these where they had a pile spill. So now I’ve got loads of beads in bags, and a few of the jars (empty).
My problem is, I dont know what type of plastic they are… all it says on the website is “Polyethylene plastic” and theres nothing on the tub. Having googled, I’m guessing this means they are either HDPE or LDPE. Anyone know which? I’m guessing HDPE but I’m not sure
Perhaps more to the point, would it cause a problem if I mixed HDPE and LDPE for extrusion ect? or should they be kept separate?
Well, for those who are interested, I’ve got my answer… Hama beads and the like are LDPE. I found it after a friend stumbled across a interesting introduction to the beads 🙂
Shame really, I was secretly hoping they’d be HDPE or maybe PET, because they are the plastics I prefer working with… but hay ho
Aren’t HDPE and LDPE pretty similar as regards melting point and other properties?
Is mixing them a problem, other than that you will end up with MDPE?
Hdpe is about 130
Ldpe about 120
So pretty close. Been asking prof Google, and I’m getting mixed reviews about mixing HD and LD
Some people say its fine, others say it splits and you get sections or blobs of each.
The one thing everyone agrees on is you need to melt the plastic early in the extruder barrel to give it time to mix. That and high pressure at the end
LDPE, that is worth knowing. Knowing people who use Hama beads, it gives options for discarded hama creations and making Hama beads out of other discarded LDPE items. (Whether it be extrude and chop or extrude to filament then 3D print, sounds convoluted, but can imagine loads printed at the same time quite quickly).
Personally I’d keep LDPE separate, at least you won’t need to shred them as they are a good consistent small size already. Separating the colours could take some time but you’ll have a good supply of a good variety of colours to make stuff with!
Having read the article at http://houseofgeekiness.blogspot.com/p/not-all-beads-are-created-equal-when-it.html the author notes that real Hama beads melt at a lower temperature than the other “own brands” such as those at Ikea. My hypothesis is that Hama are LDPE and ikea use HDPE or Hama use an additive to reduce the melting temperature.
I’d try a sample of the beads you have at the lower of the temperature range for LDPE and if it doesn’t melt then it must be HDPE.
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