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.
Warrington WA4 6HB
+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.
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. :-)
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.
As well, I expect that painting conducting strips onto parts will present some problems in segregating polymer and conducting material in the recycling process.
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.
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.