graphite fibers with Elastomeric matrix

[seawave]

hi to all
I would like to make a thin 0.25-0.37" laminate with high flexability

could some one recommend Graphite fiber with elastomeric reisen.

I would like to process it about 220-280 F so it will fit my current process as well.

 

[Compositepro]

There are many possibilities. I've worked with flexible pvc (plastisol), silicone, uretane and plasticized epoxy. Flexible resins do not allow the carbon fiber to develop full strength. The flexiblity of laminates is still limited. Carbon fiber does not stretch and compressing it results in microbuckling that can break the fiber. If you flex a multilayer laminate the neutral axis is not in the center but at the outer tensile surface because the fiber does not stretch. That puts all of the other layers in compression. What is your application?

 

[seawave]

I'm using it to support and preserve integrity after local impacts, currently i'm using carbon fiber with epoxy resin, but i'm having troubles with localizing the damage zone after impact. It feels that the epoxy is too brittle and after impact it cracks all ove and i get voids all over and losses the support, i thought going to elastomeric resin might retain the support back execpt the the areas that will shear.

 

[Compositepro]

Elastomers are not structural materialss so you cannot simply substitute an elastomer for epoxy. If you need flex and compression stiffness your only option is a toughened epoxy or similar resin. Epoxy is often toughened with elasomer or thermoplastic additives. Toughness versus strength is one of the most common trade-offs that must be made in selecting a composite structural material.

 

[allcomposites]

You can use a rubberized epoxy in order to increase flexibility and impact resistance. We have used Dow DER 736, a low viscosity epoxy diluted with glycol. Depending on your process, there is also the DOW XZ product line, a high viscous resin, and the Sikadur products form Sika. I will also suggest replacing the carbon fiber for a thin woven glass, it will perform much better on this application. If you care about the esthetic finish, you may also try basalt fibers.

 

[rstupplebeen]

You might want to also consider if graphite is appropriate. If you use a sufficiently rubberized matrix the benefits of graphite will not be realized but the cost still will. An aramid, glass or PE fiber may be more appropriate. I hope this helps.

Rob Stupplebeen

 

[allcomposites]

Two other great products are the Albidur form Nanoresins and Genioperl from Wacker. These are DGBA resins premixed with silicone rubber nano-particles. Flexibility and impact resistance is great although these products are a bit expensive. You can add one of these premixed resins to your epoxy resin to rubberize it reducing cost.

 

[Hansmeister]

As others have suggested, carbon fiber may not be the best for impacted applications. A high strain fiber, perhaps Kevlar or S-glass, may be a better choice.

I flexible resin you may want to consider is acrylic.