Isopropyl Alcohol on PLA

[dlloyd124 0]

Hi, recently my company has bought an Ultimaker S5. Since the industry we are in is heavily regulated, I need some more information than what is provided on Technical/Safety Data Sheets. Does using isopropyl alcohol have any effect on PLA? Would silicone adhere to the material well enough to be used in our practice? Is there specific research or information, in writing, that shows these materials being used on PLA?

[geert_2 347]

I am not an Ultimaker spokesperson, and not related to the company. So what I say is only from experience, and has no official value.

 

There are hundreds of different silicones, from very soft (flesh-like) to very hard, from elastic to very brittle, from non-stick for mould making to very sticky for glueing, high-temp and low-temp, platina-cured, tin-cured, liquid, paste, kneadable, sanitary/non-sanitary, filled and unfilled, overpaintable and non-paintable, chemically resistant and non-resistant,... The list is endless.

 

I mainly use non-sticking silicones for mould making, which obviously don't stick at all.

 

Then there are lots of different PLA-formulations and additives. And also surface-shape and surface-preparation could play an important role.

 

Also, there do exist activators that improve bonding of silicones to plastics, but I don't know how they work chemically.

 

So I think the only one who could answer this question, is you yourself, depending on which materials you use in which circumstances. I guess you will need to do your own strength tests.

 

The same is probably true for the use of chemicals and solvents on PLA and other 3D-printing materials. At best manufacturers could give general rough guidelines. 3D-materials may contain lots of additives: softeners, colors, UV-protective agents,... These may have different chemical resistances from the base resin.

 

Some of my models have been used in the hospital and desinfected with isopropyl alcohol without damage. But they are only for single use, so the chemical contact is very superficial and short, they are not drowned into it.

 

Additionally, expect PLA to get harder and more brittle over time. Snap-fit mechanisms that work well originally, are likely to break if you try them after a year, in my experience. It seems that this is due to changes in crystal structure, from amorphe to more crystalline, if I understood it well.

 

Also, expect PLA to deform in a car, or in sunlight behind a window. Even in moderate spring or autumn weather. This too is from experience...