bhyrav (Materials)
If you are using epoxy resin you can sometimes remove the epoxy from the carbon fiber with acetic acid. this may take a while.Miller-stephenson in Danbury Ct., has some commercial strippers for removing epoxy potting compounds from electronic components. These will also work,although they too are slow.
B.E.

Thank you very much for your reply, but I am using Vinyl ester resin and I tried it with acetone to dissolve that, and also concluded (basing on literature)that it is very difficult to find a chemical which can completely dissolve the matrix material.
thank you again..

bhyrav (Materials)
Try using  methylene cloride.
B.E.

Berkshire:
Thank you !! I will try this
bhyrav

In the aerospace industry the standard method for fiber volumes is acid digestion. A hot mixture of conentrated nitric and sulfuric acid is used. The fibers are the carefully washed and filtered. A test takes several hours. Methylene chloride will not work. It may breakdown the resin to some extent but not enough to be cleanly separated from the fibers.

compositepro:
can you explain on what criterion we should select the chemicals for acid digestion?
Thanks

Compositepro (Chemical)
If you are going to use acid digestion with Vinyl Ester resin, surely you are going to have to use concentrations above 50% nitric acid to water and at temperatures close to boiling to have any effect at all on this resin.
B.E.

See ASTM D 3171. This is somewhat decsribed here:
http://www.tc.faa.gov/its/worldpac/techrpt/ar04-50.pdf

Thank you very much lot of useful information about testing

Another standard acid digestion method is to use conc sulphuric acid ( 98% ) heated to about 160 Deg C . ( You'll need a good fume cabinet ) . Upon reaching this temperature SLOWLY pippette into the mix 10 mls of 100 vols Hydrogen Peroxide ( This is very volatile so take care )until a clear solution is obtained . ( If disolouration is still observed you can re-heat and add more H2O2 ) . The remnants can then be filtered .

In terms of the measurement the more critical aspects are the determination of the volume and density of the original specimen . It is expected that the density of the resin and the fibre are known .