Plastic 3D Printing filaments are polymers, polymers are made up of a repeating long chains of monomers that weave themselves together like a rope. Some 3D printing filaments are co-polymers which just means it is made up of a chain of one or more different monomers, but essentially they react to water in the same way.
Different Polymers you will commonly find in 3D printing filaments are:
- PET – Poly(ethylene terephthalate), commonly known as Polyester
- PETG – PET with a Gylcol modifier to aid with 3D Printing (also called Co-Polyester)
- PLA – Polylactic acid (also called polylactide)
- PP – Polypropylene, or poly(propene)
- PE – Polyethylene
- PS – Polystyrene
- PA – Polyamide, commonly known as Nylon
- ABS – Acrylonitrile Butadiene Styrene, Co-Polymer made from 3 monomers
Now that we know that our 3D Printing filament is a polymer which is made up of long chains of monomers we can start explaining how water / moisture affects the polymers while they are being 3D printed.
Most polymers are hygroscopic
Which means that as air circulates around and through them they absorb the moisture that is in the air. All polymers absorb water at different rates so how fast the adverse affects happen will greatly depend on the material and the humidity of the air. for example Nylon can absorb up to 9.5% of its weight in moisture and in hours it is able to absorb enough moisture to start ruining prints.
When you extrude a polymer that has absorbed water, the water in/on the material vaporizes creating steam bubbles and voids in the strand of filament. Some of the signs you may notice are hissing or popping sounds coming from the extruder, Excessive stringing on the print or Poor surface finish.
The steam inside the hotend causes a lot of problems from a lack of consistent pressure in the hot end to an affect called hydrolysis.
Hydrolysis is the affect we are talking about here, hydrolysis causes de-polymerization (breaking down the chains of monomers) there can be a lot of different affects to the polymers properties when the polymer chain lengths are decreased.
The most common affects of hydrolysis in 3D printing filaments are:
- Excessive stringing / oozing ( Shorter polymer chains have a lower viscosity and flow easier )
- Loss of layer adhesion
- Loss of tensile strength
- Loss of clarity in transparent materials
- Poor Surface Finish
If you would like to keep your filament dry the best way is to always store it in a Drybox, you can purchase a 3D printing filament drybox from us.
June 27, 2019