Patent ID: 8591859

Claim:
A method of making a carbon fiber having improved tensile strength and modulus of elasticity, the method comprising: advancing a carbon fiber precursor polymer through at least 4 passes in an oxidation oven to produce an oxidized fiber, the oven having an oxidizing atmosphere at a temperature between about 175 to 300° C.; subjecting the fiber to a % stretch in a first pass that is between 5 and 30%, a % stretch in a second pass that is between 5 and 20%, and a % stretch in a third and fourth pass that is between 2 and 15%; passing the oxidized fiber through a furnace at a temperature between about 400 and 800° C.; and carbonizing the fiber by passing the fiber through a furnace having a temperature that is between about 1300 and 1500° C., and wherein the resulting carbon fibers have a tensile strength from about 950 to 1166 ksi and modulus of elasticity of about 45 to 53.3 Msi.