Just to add a bit more support to whats already been said, I came across the chart in the link below that compares the properties of e-glass, s-glass, carbon and Kevlar/Amarind relative to e-glass. Its from the fgi website ( www.fgi.com.au
)http://myvirtualshed.blogspot.com/2011/ ... rties.html
The flexural modulus of carbon compared to the others is interesting. The high number means that the material is very stiff and carbon is known for not flexing much and with its strain to failure being 1/3 that of eglass means that it is basically very brittle. I'm guessing that this means if you are wanting a carbon board with a good amount of flex then the board will need to be very thin in order that it can bend without reaching the maximum strain. All the boards I've come across while googling around use carbon and e/s-glass to get their balance of strength and flex while minimising the total weight of the laminate used.
Something else they comment on which has been mentioned in the previous post is that kevlar holds together when the baord breaks. Whereas carbon is brittle and rips apart when it fails, Kevlar exhibits 'ductile' failure much like metal where it tends to stretche and thin out rather than rupture. Aparently the attractive characteristic is used i nboat building to keep the boat together if the hull should crack so that water doesn't rush in.
Using s-glass seems to be a great trade off in cost-strength/flexibility. Has anyone worked with s-glass to be able to compare it to e-glass?