ABS HDPE blend

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It has been observed independently by Bogdan and Nophead that ABS and HDPE appear to be miscible. This becomes apparent when switching from coloured ABS to HDPE (or vice versa) in the same extruder. As the first plastic is flushed out by the second you get a filament that slowly changes color and physical properties from one to the other. The plastic appears to be well mixed in the extruded filament and cannot be separated.

This raises an interesting possibility. ABS and HDPE can both be extruded at the same temperature, i.e. 220-240C. It should be possible to build an extruder with two feeds but a single heater and nozzle. The ratio of the two plastics could then be varied dynamically throughout the building of an object.

HDPE is a very good bearing material, being tough and very slippery, but it doesn't stick to anything other than itself, other forms of PE and PP. Large objects also tend to warp. It may be possible to make the base of an object with 100% ABS, so that it sticks to the bed, and then graduate to 100% HDPE to make bearing surfaces. An ideal application of this would be the Prusa_Mendel X-carriage that has a large flat base and four bushings that need to be slippery and hard wearing.

--Nophead 14:24, 15 January 2011 (UTC)

I just happened across this article. I was talking to a local supplier of plastic welders/rod ($1/foot for ABS (~$900/lb?)... Wow.) Anyways, he mentioned that almost no one uses ABS for anything anymore because it's brittle, they either use another material or ABS/HDPE blends. So I guess this is just news to us. If you can buy blended plastic, someone could make blended wire for us if it turned out to be useful? Would a blend stick well enough to start and still maintain the slipperiness? Some experimenting with ratios may be needed, or I can see of these guys can say what common blends are used and why.

--Epengr 21:44, 22 March 2011 (UTC)

I am not convinced that the two plastics are very miscible. The article promotes the opinion that the two plastics join together very easily, However, I just tried heating HDPE and ABS with a match until they bubbled and applied them together. There was practically zero adhesion between the two. I did the same experiment with PET, and the bond was clearly much better. the plastics didnt join, but with the PET it took about 1 kilo to seperate the melted surfaces, with HDPE it took 100 grams.

--Ufomorace 14:24, 15 January 2011 (UTC)