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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6797553/ https://www.hatchbox3d.com/collections/pla

We are 3D printing masks that need to be used by medical staff treating COVID19 patients.

The first link is an overview of the material we are using for masks in general.

The second is the specific product we are making masks out of.

Quesions:

1- To sterilize; can we safely do 120C for 30 minutes without the mask losing shape? What about 70C for 30 minutes? Will it affect integrity and water/air proof "ness"

2 - Should we sterilize in humid air? dry air? again to maintain shape and impermeability

3 - will this be stable with exposure to 1) Vapor H2O2 @ >480 ppm for 30 minutes? 2) 1:9 bleach:water immersion? 3) household disinfectants (google Lysol)

We are making masks from this material and would be happy to recieve insights from people in the field.

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    $\begingroup$ "I need answers to these questions accurately as soon as possible." Asking random people on the Internet for advice is no substitute for a quality assurance plan with protocols for a device for medical use. $\endgroup$ – Transistor Apr 5 at 13:03
  • $\begingroup$ PLA's glass transition temperature is only around 65C. You might do better to try ABS for the printing. Either way, I agree with @Transistor. You are going to have to test parts. $\endgroup$ – Eric S Apr 5 at 15:29
  • $\begingroup$ @Transistor I agree with you in ideal case I would stick to the regular route, but I am posting for a doctor friend of mine, who is in a desperate situation along with his coleagues. So we need a quick route $\endgroup$ – SagarM Apr 5 at 16:57
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You are probably using an FMD type printer. No matter how good your printer, or the density of the print, you will have porosity. You need the temperature to denature the proteins of the virus. If someone is wearing a mask all day breathing hot air into it, especially with PLA, there will be absorption into the plastics. I think you cannot assume that a chemical method will infiltrate into all pores to destroy viral particles. Also you would need to be aware of the residual chemical left behind from the process in the plastic. PLA is very hygroscopic.

See this article: "For gravity displacement sterilizers the penetration time into porous items is prolonged because of incomplete air elimination. This point is illustrated with the decontamination of 10 lbs of microbiological waste, which requires at least 45 minutes at 121°C because the entrapped air remaining in a load of waste greatly retards steam permeation and heating efficiency."

https://www.cdc.gov/infectioncontrol/guidelines/disinfection/sterilization/steam.html

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