You oughta look in the composites forum, i'm sure if you do a search you can find what you are looking for. I hadnt heard that kevlar had near zero elongation before failure, but if thats the case then you would think it would be good for stiffening, wouldn't you?

Although, kevlar is used for things you would think would need flex. Applications such as pull pull cables, bullet proof vests, and containment shrouds on jet engines. I can tell you that kevlar is hard as hell to cut with scissors and CF is easy.

Anyway, i would look in the composites forum, you will probly find your answers there.

Good luck