Plastic/ Polymer Search 2

[Solas2005]

Hi all,
Just wanted to pose a question. I am looking at creating 0.380mm wire from a plastic/ polymer composite. Ideally the wire needs to have similar properties to a stainless steel needle of the same diameter. I've been messing around with various plastics but all have either proved too flexible or too brittle at that diameter. The wire is going to be used to make surgical lances so it cannot be flexible or brittle.
Has anyone come across a plastic/ composite that may do the job?
All help greatly appreciated.
Kind regards,
JPM

 

[patprimmer]

I would require a lot more information before I could attempt any sort of answer.

Like what have you tried so far.

Does it need to withstand sterilization.

Does it need to be certified for FDA or biological compatibility.

Why plastic if stainless steel works already.

Regards

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[Solas2005]

To date I've tried urethane casting resin, polyester casting resin.
It does need to withstand sterilisation.
Biological compatibility is desirable. FDA certification would be nice but not necessary.
Stainless steel doesn't work well enough. Stainless steel lances are causing problems when used in conjunction with other metal parts in that they scrape the surface of the metal part damaging the passive layer and thereby encouraging corrosion.
Thanks in advance,
JPM

 

[patprimmer]

You only mention casting resins, so I guess a mould is not available.

You could try acrylic or PMMA casting resins. There are dental grades used to make false teeth.

It is quite rigid, but also somewhat brittle.

The next option would be to make a prototype mould and try some materials like Polysulphone or polyimide or Poly ether ketone's



Regards

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[Solas2005]

Thanks for your help. I'll try those and let you know the outcome.
Much appreciated.
JPM

 

[rnd2]

Have you considered a pultruded composite made from a mixture of glass and treated carbon fibres and using a suitable high temperature resistant resin matrix? What is the withstand temp requirement? The resulting composite would be a corrosion resistant, very stiff AND tough material, able to withstand steam sterilizing.

 

[Pud]

Hi,

You might also consider LCP's - they are ideal for very thin sections and have strength approaching stainless steel in very thin sections. (Talk to Ticona, who make CF reinforced grades, Dupont do not make CF grades as far as I know..)

Alternatively can you overmould a stainless core?

Rgds

Harry

 

[Solas2005]

RND2,
Thanks for the help. What specifically did you have in mind? Is there an off the shelf compound that I could obtain? Where could I get it? Withstand temp max. 212F I'd reckon.
Harry,
Thanks for your suggestion. I'll also contact Ticona.
The successful compound may also need to have the capability to be EtO sterilized. This isn't absolutely necessary though.
Thanks for all help received. It's greatly appreciated.
JPM

 

[rnd2]

Solas2005
While I doubt there is an off the shelf material to handle exactly your requirement I expect it can be custom made.

 

[gambro]

To my knowledge, PEEK is currently being used for this kind of application. The medical grade type is called PEEK-Optima and manufactured by a Swiss (?) company called Invibio. It's strong, flexible, implant tested and most certainly withstands any type of sterilization and to my knowledge temperatures in excess of 212°C. There are also fiber-reinforced off the shelf grades available. Please note that medical grade PEEK is veeeery expensive.