Dear Shelda,

I think you need to be more specific (for yourself and for for us to help). Given the way your question is asked, I can only answer that generally, it goes like this:

- Define what «the best» means for your use case and what are quantitative or qualitative limits for these properties.

- Either look for properties of families of epoxy or specific product data sheets for these characteristics.

- Check for product availability for those who correspond the best to your requirements.

The best won't likely be the same thing for each of the functions (manufacturing, aestethics, strength, durability, cost, etc).

You can build a multi-parameter metric based on Ashby's material selection method.

Best regards,

Laurent

Laurent Cormier

Thanks Laurent for your attention.

You are right, I am new in this field and my question is general. Suppose that it is a manufacturing case, which cost, time, and specific mechanical properties is needed. I can find the properties of different epoxy (like curing time) , but how I can figure out if this epoxy works good to achieve the composite with specific properties. I mean whithout experiment can we find out which group of epoxy might be good for the case? What kind of information should I looking for?

Dear Sheida,

Long answer:

Braided carbon fibres refers to the fibre form, but does not define the process used to make the composite part. Before choosing the resin, you need to chose a manufacturing process. Common processes (apart from prepreg in or out of autoclave and fibre placement which I don't think are relevant here) are wet lay-up, vaccum molding after wet lay-up, vacuum resin infusion, resin transfer molding (RTM,), vacuum assist RTM (VARTM). Each have different mold and workmanship requirements and warrant different resin properties. Note that wet lay-up is the easiest process, but produces relatively low fibre contents so it is rarely preferred for high performance fibres like carbon. Note that braided fibres are often used for tubular shapes and manufacturing those implies many peculiarities which are beyond such a post.

Once you know the process and have fixed the desired mechanical properties outcome. You can identify desirable resin properties and select a resin (do you really need an epoxy or something else may be better?).

Seriously, Ashby's method is good. Have a look at it, it is in your school's library:

https://primo-pmtna02.hosted.exlibrisgroup.com/primo-explore/fulldisplay?docid=USaskIII.b31120076&context=L&vid=USASK&lang=en_US&search_scope=UofS&adaptor=Local%20Search%20Engine&isFrbr=true&tab=default_tab&query=any,contains,material%20selection%20in%20mechanical&facet=rtype,include,books&mode=Basic&offset=0

Shortish answer:

Diglycidyl ether of Bisphenol A (DGEBA) resins with polyamine hardeners are to my knowledge one of the most common epoxy used for composites. They are quite tailorable in terms of properties (at the resin manufacturer level), provide good overall mechanical properties, cure at relatively low temperatures and are not the most expensive. If you need very low viscosity or higher Tg, then you may need to look elsewhere.

Regards,

LC

Curing Epoxy on a braided carbon fiber - is a very inaccurate outdated method (sorry, but it is true)

Leonid V Vladimirov Thanks for the comment, but it is a manufacturing case, not a new research project.

Laurent Cormier

Thanks for the valuable comments. I was wondering if your research group works on these kind of projects? We are working on a manufacturing case and we might need connection with some university researchers in this field.

Regards,

Sheida Shiri

Dear Leonid V Vladimirov, as the question clearly implies impregnating epoxy in braided (not woven) carbon fibres, I do believe my answers are relevant although not referring to the latest state of the art in terms of composites manufacturing. However, I feel that although clear in its intent, your answer falls short of being helpful.

Would you allow us the chance to correct this? I would sincerely be interested in knowing what you consider are the more current approaches for composite manufacturing. My quick guesses are you might be referring to automated prepreg tape or fibre placement instead of braided or knitted reinforcements, or to the use of thermoplastic resins instead of epoxy, to the use of taylored polymer morphologies or nanometric additives?

Or is it carbon fibre composites in general that you feel are outdated?

Regards,

Laurent