The discussion centers on the ability of bleach water, rubbing alcohol, and quaternary compounds to penetrate microscopic pores in plastic, specifically those measuring 10 microns or less. Participants agree that rubbing alcohol (isopropyl alcohol, IPA) is more effective than bleach due to its lower surface tension, which enhances wettability. The consensus is that the surface energy of the plastic must exceed that of the liquid for effective penetration. Practical tests, such as observing the wetting behavior of the liquids on the plastic surface, are recommended to assess sanitization effectiveness.
PREREQUISITESThis discussion is beneficial for mechanical and aerospace engineers, medical professionals involved in sterilization processes, and anyone interested in the sanitization of plastic materials, particularly in medical or food-related applications.
Same, i have been researching like crazy. I am a mechanical and areospace engineer student but was asked to help spear head a project with doctors and other medical staff. I have been telling people that using certain plastics for basic things that we need at the moment is ok. They(not doctors, others involved) keep telling me that you can't sterilize the plastic with bleach water or rubbing alcohol because it won't get into the pores. I beg to differ. It seems that when teating out what you mentioned, both sanitizing liquids look wet, but rubbing alcohol seems to stay that way longer. I wiah i had the equipment to see that close to the plastic and see if stuff made it into sanitize hahasome bloke said:Rubbing alcohol is probably the way to go. as Wukunlin says, the "wettability" of the surface of the plastic is related to the surface tension of the liquid and the surface energy of the plastic.
If the surface energy on the plastic is greater than the surface energy (tension) of the liquid then it will go into the pores and the surface will "wet up".
An easy way to observe this is whether it looks like the surface is wet, or if the liquid has formed droplets. rub some of each onto the plastic surface in question and see whether it stays wet (alcohol will evaporate fast) or if it forms droplets straight away, like water off a ducks back. the wetter it looks, the better it has gotten into the pores.
useful info (more related to filter membranes but still relevant to pores in a plastic surface):
https://www.merckmillipore.com/GB/en/life-science-research/chromatography-sample-preparation/membrane-learning-center/Wettability-Characterization/lp2b.qB.f7IAAAFM20p88eJt,nav
Background - work in a filter company, been researching how this works this week!
LT72884 said:Same, i have been researching like crazy. I am a mechanical and areospace engineer student but was asked to help spear head a project with doctors and other medical staff. I have been telling people that using certain plastics for basic things that we need at the moment is ok. They(not doctors, others involved) keep telling me that you can't sterilize the plastic with bleach water or rubbing alcohol because it won't get into the pores. I beg to differ. It seems that when teating out what you mentioned, both sanitizing liquids look wet, but rubbing alcohol seems to stay that way longer. I wiah i had the equipment to see that close to the plastic and see if stuff made it into sanitize haha
Thanks for the link
Wow that's awesome! I am going to show them this for sure.some bloke said:You shouldn't need to visibly see the pores filling. The test showed what I expected as bleach is water based, and water has the second highest natural surface tension, after mercury. IPA is significantly lower, so the wettability of the surface with IPA should be far better than bleachy water.
I would suggest showing them this evidence, with the wetting test. I work in a factory which operates as a clean-room manufacturer for filters used to remove viruses from blood, and everything is cleaned with IPA. It works for all standards of a clean-room, so it should be fine for doctors & other medical staff.
The higher the concentration of alcohol, the better, IPA is usually 70/30 alcohol to water. it's very effective at cleaning plastic, and any other non-absorbent surface.
If your 3D printing something to eat out of, you may want to make sure that the plastic you use is food grade.LT72884 said:One last question, kind of a side question regarding 3d printed parts. If i were to make a soup bowl out of a 3d printer and eat out of it, i know it has layer gaps and pores in the structure. Technically i good use ipa to sanitize it and should be fine? Now when sanitizeing with ipa, is it best to spray it on or dip?
Yeah, I am using poly lactic acid as my material. The same stuff food packaging is made from:)BillTre said:If your 3D printing something to eat out of, you may want to make sure that the plastic you use is food grade.
Alternatives to using the plastic for home printers would be to use a 3D printer website where you would probably have a greater selection of materials and where, if they are food grade, they will probably be advertised as such.
Good question. I need to find out if the coloring agent is food safe as well. I doubt it is. But let's pretend it is, rubbing alcohol SHOULD be able to sanitize it... I am hoping. And no I am not going to test out unless i can get some pure pla hahaBillTre said:Is it pure?
Plastics can have bad additives unless it is actually labeled as food grade.