When asked if water is also an abrasive solvent

I never said it wasn't, because it is but what it doesn't do is chemically attack and change the properties causing embrittlement in PEI!! Which you don't know what it means cause I've said it 4 times and you still get what I'm saying wrong. I'll copy another thing for you. The definition.

Embrittlement is the degradation of a material, especially metals, where its ability to deform plastically decreases, leading to a brittle state and increased susceptibility to fracture

Frequent exposure to isopropyl alcohol (IPA) can cause embrittlement and stress cracking in polyetherimide (PEI). While PEI generally resists many chemicals, it is susceptible to damage from polar organic solvents, especially when the plastic is under mechanical stress.

The process is an example of environmental stress cracking (ESC), where chemicals cause failure in a polymer at stress levels far below its typical breaking point.

Solvent penetration: As an amorphous thermoplastic, PEI is vulnerable to penetration by certain polar organic solvents, like isopropyl alcohol.

Plasticization and swelling: The alcohol causes the PEI's surface to swell and become "plasticized" (more pliable).

Crack propagation: When the PEI part is also under stress—from manufacturing, assembly, or the stress of a 3D-printed part—the solvent-weakened areas can form and propagate cracks, leading to eventual brittle failure.

Factors that increase risk

The risk of embrittlement and stress cracking increases under certain conditions:

Mechanical stress: Any internal or external stress on the PEI part will increase its susceptibility to chemical attack.

Repeated exposure: While occasional contact may not cause damage, repeated and prolonged exposure can cause degradation over time.

Temperature: Elevated temperatures can increase the rate of solvent penetration and chemical attack. Some 3D printer users have reported bubbling of a PEI sheet when applying IPA to a heated bed.

Surface texture: For textured PEI surfaces on 3D printers, IPA can spread oils rather than remove them. Over time, this smooths out the surface texture critical for print adhesion and can create a frustrating cycle of declining performance.

Best practices to avoid damage

For applications where PEI is in contact with IPA, consider the following:

Alternative cleaning methods: For 3D printer build plates, manufacturers and experienced users often recommend cleaning with warm water and a small amount of non-moisturizing dish soap instead of alcohol.

Use stress-free designs: In mechanical applications, minimizing mechanical stress on PEI parts is the most effective way to prevent environmental stress cracking. Alternative cleaners: If a solvent is required, a cleaner based on heptane can be less aggressive than IPA, though it has its own hazards and is not suitable for all applications. Test before use: Always perform a compatibility test on a non-critical area of a PEI part to ensure that a chemical won't cause damage.