A better 3D printing material than PLA

Maybe

PLA is a great 3D printing material with one major flaw. It’s the stiffest of available materials, not toxic, cheap, and prints easily. The main downside of it is that it melts at an annoyingly low temperature. It would be nice to have some material which is like PLA in all characteristics but has a higher melting temperature. It turns out that such a material exists and it is… PLA.

That last statement requires some explaining. The distinction is whether PLA is annealed or not. Annealing is a process where a material is brought up to a high temperature and then very slowly cooled down, causing it to be more crystalline (or at least lower energy) at the molecular level and thus stronger/tougher/having a higher melting point. PLA the material does this very well but if you apply the process to 3d printed parts they warp because internal stresses within the parts get released. It’s like the objects are made out of frozen rubber bands which were stretched out as the filament was layed down and heating it up allows them to spring shut.

The causes of this problem are that the filament wasn’t made hot enough when it was extruded and wasn’t cooled down slowly enough afterwards. The straightforward way of fixing this would be to do exactly that: make the filament so hot it’s a liquid when it comes out, then cool everything down slowly afterwards. That would require some kind of soluble support material which is solid at those high temperatures, printing everything at 100% fill because it’s a liquid, and keeping the entire 3D printer at those high temperatures. While this approach may work it’s unlikely the printer itself would still be cheap and reliable with all that literally getting cooked while it’s running.

A more practical approach may be to invent a PLA blend which anneals better. If PLA is interleaved with another material which forms a matrix around it, maybe that other material could melt at a much higher temperature, meaning it’s still frozen at the temperature PLA needs to be heated to to get it to anneal, so doing the annealing process post-printing wouldn’t cause the item to warp. The obvious candidate for this is carbon fiber. Maybe you could make carbon fiber PLA with massively more carbon fiber than anything currently available, to the point where the melting point is dramatically increased, then print using that and anneal later by taking the parts back up to the melting point of PLA but not the melting point of the combined material. Whether carbon fiber specifically or anything in general can get PLA to behave that way I don’t know, and obviously a brass nozzle couldn’t handle that material, but maybe some experimentation could result in a new type of filament which could make very high quality parts quickly and easily.