There is a severe shortage of metal smooth rods. Is plastic an alternative?

[tareko]

There is a severe shortage of metal smooth rods. However, a local plastic producer is able to produce plastic rods out of ABS, polypropylene, and perhaps other plastics. Can polypropylene be a suitable replacement?

[apopanda]

Most likely polypropylene isn't suitable, it is less stiff than many other plastics. It is slightly stiffer as compared to polyethylene (which is also a polyolefin), which is what we use with the tourniquet, but it still isn't "good". Plastics also like to deform and stretch under load, especially overtime.

A more accessible "rod" could be rebar? The diameter seems to match. No idea if it'd be suitable in the OR though, or if it's possible to sterilize it sufficiently. The ribs could also be an issue

Edit: galvanized rebar for corrosion resistance

[tareko]

We had a long meeting with a plastics manufacturer today to explore this idea. He proposed injection-molded polycarbonate rods. He also suggested the use of Nylon PA, although he didn't know exactly what kind (it sounds like 12 by his description). He claims both of these plastics are available.

Next step: We're looking for rod samples and will do some testing on them with the engineering team to try to characterize the properties. At that point, we can see if the rods are appropriate for different limbs (e.g., arms) or under a certain weight (e.g., 70kg). The process of getting samples for testing will take about a week.

[apopanda]

Do note a potential incompatibility between OPA mentioned in issue #14 and polycarbonate
source:
https://www.atamanchemicals.com/o-phthalaldehyde-opa_u33306/

I don't know much about chemistry, other than "isopropyl and acrylics / polycarbonate is a no-no" though, so this info probably needs double checking.

[tareko]

Do note a potential incompatibility between OPA mentioned in issue #14 and polycarbonate source: https://www.atamanchemicals.com/o-phthalaldehyde-opa_u33306/

I don't know much about chemistry, other than "isopropyl and acrylics / polycarbonate is a no-no" though, so this info probably needs double checking.

Thanks for this flag. It's important to keep in mind as we move this forward. There are several other options, like the use of sodium hypochlorite (bleach), and potentially other chemicals that might serve this purpose considering that the parts are not implanted, but rather stay outside the body.

[tareko]

@jenwilsonglia and I have been working hard from the Canadian side on acquiring rods that might be candidates to replace steel rods. Current candidates for testing:

• Acetal Copolymer Rods (POM-C) - too flexible
• Teflon rods
• Nylon rods. Only nylon PA6 rods (not PA12) seemed to be available
• Impact-resistant polycarbonate rods
• High-strength glass-filled impact-resistant polycarbonate rods
• Rigid Glass-Filled Wear-Resistant Nylon Rods - There are some other nylons at McMaster-Carr, but this was the only one that looked promising
• Rigid Glass-Filled Wear-Resistant Easy-to-Machine Delrin® Acetal Resin Rods

One small complication is that these parts are available in inch formats, and mostly in 1/4 and 1/2 inch. So we'll test against 1/2 inch and then if that works out figure out if these plastics are appropriate as 3/8, which is the closest to 10mm. It's unlikely we'll find 5/16, which is the closest to 8mm.

The suppliers we've currently identified:

• Amazon
• McMaster-Carr
• Polymer Shapes - Has a location in London
• Grainger - Has a location in Sarnia

[tareko]

The next step in this process will be for @Bader13012 to get spec sheets for all candidate plastic resins available in Gaza, so we don't waste our time testing materials that are simply impossible to find there.

[jenwilsonglia]

Here are spec sheets from Polymer Shapes in London, ON - for:

PBI ( Polybenzimidazole)
AEP-Duratron™ CU60 PBI_en_US.pdf

PAI ( Polyamide-Imide)
AEP-Duratron™ T4203 PAI_en_US.pdf

PEI ( Polyetherimide)
AEP-Duratron™ U1000 PEI_en_US.pdf

PPEK (Poly-ether-ether-ketone)
AEP-Ketron™ 1000 PEEK_en_US (1).pdf

PPSU( Polyphenylsulfone)
AEP-Sultron™ LSG FG R5100 PPSU_en_US.pdf

[tareko]

@Bader13012 Please update the issue in terms of where you got with spec sheets from the Palestinian supplier

[tareko]

Here are spec sheets from Polymer Shapes in London, ON - for

Can you get sample rods of these? 8mm x 30cm is probably what we'll use as our main text, though 10mm is also welcome.