39 s modulus of 25 000 000 psi a bar similar to that described in example 1 was further heated to 2000 u00b0 c in argon again at about 500 u00b0 c per hour this bar exhibited a modulus of rupture of 83 000 psi and a young 39 s modulus of 33 000 000 psi a bar similar to that described in example 1 was heated further to 2300 u00b0 c in argon this bar exhibited a modulus of rupture of 83 000 psi and a young 39 s modulus of 50 000 000 psi precursor fiber oxidized as described in example 1 was cut into short lengths having a mode of approximately ten mils using a thomas wiley cutting mill a sample of this material was placed in a graphite mold and compacted in air at 2 500 psi at 270 u00b0 c for approximately 20 minutes to produce a consolidated bar having the same dimensions as that of example 1 the bar was subsequently pyrolyzed by heating at a rate of 100 u00b0 c per hour to 1 200 u00b0 c in an argon atmosphere the resulting carbon bar had an apparent porosity of about 5 percent and exhibited a modulus of rupture of 20 000 psi a scanning electron micrograph of the fracture surface of a similar test bar is shown in fig2 a bar similar to that described in example 5 except compacted at a pressure of 600 psi had a porosity of about 30 percent and a modulus of.