I am planning on making a pair of carbon cycling shoes. Looking for some super flexible epoxy for the upper. Will be doing in two parts, lower then adding upper with secondary bond. Thoughts.
Sicomin SR8150 , like rubber.
Call up polymer composites inc… They are working on some epoxy that turns carbon into a flexible sewable fabric.
Urethane and clear plastic films are the first thing I think of. Soft plastics like PE or PP, but they sometimes are not optically clear. Ionomers are clear, and soft. I’m sure there are other elastomers that can work.
Of course, plastic normally isn’t viscous enough to get into the fiber tows, so you end up with some dry fibers on the ends. Sew it up, and you should be ok if you want it for looks only.
Urethane should work well, or ask around for a clear low-strength ester based resin, or epoxy.
Have you used this stuff? Is it easy to work with?
THey’re site says it has a shape memory? So it has to be formed in shape?
Only one US distributor… I"ll have to give em a call.
It’s like any other epoxy, just lay up in a mould. Sicomin has some small packaging options, to give it a try.
It’s like the epoxy hasn’t fully hardened, but isn’t tacky.
I’ve tried it to use on bumpers, but indestructible bumpers(aramid/flexible epoxy) don’t earn a company much money 
it’s nearly clear too.
So it’s rigid enough for a car part? It doesn’t flop around when you drive?
I have a few projects that need a resin like this, thanks for the heads up.
This flexibility can be possible with epoxy?
https://www.youtube.com/watch?v=IoxZybhorS0
For high elongation. Urethane resin could have a higher tensile strength than epoxy? Any compatible with matrix fexible infusion?
I have used regular epoxies but mixed with a little less hardener than the Data would say so you get an under cured resin.
This was for a flexible Kevlar hinge.
Depends on your layup and fastening ofcourse, but it’s used in a few dakar cars for the bumpers too.
Not wishing to be doom and gloom…but I worked for an R&D centre and our biggest project was working on flexible carbon systems for nine months.
We tested hundreds of formulations, predominately those from urethane and epoxy family. Most systems would pass UTS but fail in the fatigue tests.
Our biggest issue was fatigue and the answer was how you manage the transition zones between the high and low flexural areas.
I can’t see how a material made with a resin of uniform modulus would work in all areas due to the uneven distribution of loads you would find in a shoe. I’m not saying it can’t be done, but it took months of testing to find a formulation we were happy with for our application.
One of the most interesting ones was a silicone product that you activated and applied to the carbon.
It resilient and supple, but wasn’t too good on the packing ratio. Maybe not so important in this case?
Thanks to all who have commented. The shoe will be predominately stiff resin as in bath tub construction with flexible upper quarter for ease of getting it on. Shouldn’t be a lot of stress on the flexible resin.