Tuesday, December 06, 2005
Polymorph and polycaprolactone
I have now obtained a sample of polycaprolactone granules and used it in place of Polymorph. It works perfectly to make rods for the RepRap extruder. I used granules of CAPA 6800 polycaprolactone (2-Oxepanone, homopolymer; molecular weight 80,000, CAS number: 24980-41-4) from
Solvay Interox Ltd.
Baronet Works
Lower Walton
Warrington WA4 6HB
U.K.
+44 (0) 1925 643210
The Solvay website is here. CAPA 6800 is supplied by the company in 20 kg paper sacks, or 500 kg bags.
There is a more complete write-up on polymorph on the RepRap Wiki.
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I've contacted the NZ distributor and I'm attempting to arrange samples and bulk product at this end.
Vik :v)
Vik :v)
Okay Adrian, reading your twiki on CAPA 6800 I understand that this is the material you want to unify work on for this iteration of the project. If that's not so I need to know.
I talked to Solvay's US agent in Houston just now and he is sending me a 5 kg sample. That should last me a while if I'm careful.
Jeff Neidinger in Houston gave me a price range of $5.30-3.50/lb for CAPA 6800. That means that a single, 20 kg sack will cost something like $234. That's a bit steep compared to something like polypropylene, but not outrageous.
This looks like a really good material. :-)
I talked to Solvay's US agent in Houston just now and he is sending me a 5 kg sample. That should last me a while if I'm careful.
Jeff Neidinger in Houston gave me a price range of $5.30-3.50/lb for CAPA 6800. That means that a single, 20 kg sack will cost something like $234. That's a bit steep compared to something like polypropylene, but not outrageous.
This looks like a really good material. :-)
I think that polycaprolactone, polymorph and friendly plastic are all essentially the same thing, despite slight differences in the FTIR shown on the wiki. We sincerely hope that 25 kg would run a RepRap machine for quite a while, including making several other machines...
So after you lose interest in something you made, you can just re-melt it back into feedstock.
If that works well, a 20km sack could last almost indefinitely...presuming you are making things of a disposable nature and that they remain clean enough to produce a sufficiently unpolluted feedstock.
If that works well, a 20km sack could last almost indefinitely...presuming you are making things of a disposable nature and that they remain clean enough to produce a sufficiently unpolluted feedstock.
My own experience in working with polyethylene suggests that you will lose some of your polymer to oxidation. Much of that oxidation might be curbed with more careful heating processes than I had, though.
As well, I expect that painting conducting strips onto parts will present some problems in segregating polymer and conducting material in the recycling process.
As well, I expect that painting conducting strips onto parts will present some problems in segregating polymer and conducting material in the recycling process.
The bugbear is little particles of non-plastic crud in the recycled stuff clogging the nozzle of your extruder. It's bad enough keeping 'em out with new plastic granules.
Mind you, if we're using a large deposition nozzle for bulk filling or moulding, we can tolerate more impurities.
I've reused Polymorph a lot and it goes "Old Underwear" grey but retains plasticity. One batch went yellow. Not underwear - Polymorph.
Vik :v)
Mind you, if we're using a large deposition nozzle for bulk filling or moulding, we can tolerate more impurities.
I've reused Polymorph a lot and it goes "Old Underwear" grey but retains plasticity. One batch went yellow. Not underwear - Polymorph.
Vik :v)
If the plan is to populate the world with RepRap machines, we'd better consider the recycling of polymorph to be right up there on the priority list or else the amount of landfill consumed by RepRapped goods could easily exceed plastic waste from all other sources!
If the machine did indeed have a high precision nozzle which required clean polymorph - and a bulk fill nozzle that could take recycled stock (possibly including metallized stuff) - then the issue of recycling metallized parts would also be reduced because you could always lay down a thin 'guaranteed clean' insulating layer of fresh polymorph from the high precision nozzle before laying down fresh metallized tracks.
If the machine did indeed have a high precision nozzle which required clean polymorph - and a bulk fill nozzle that could take recycled stock (possibly including metallized stuff) - then the issue of recycling metallized parts would also be reduced because you could always lay down a thin 'guaranteed clean' insulating layer of fresh polymorph from the high precision nozzle before laying down fresh metallized tracks.
I've observed HDPE going yellow on the surface when it was overheated. I took the colouring to be oxidation.
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