Improving carbon fibre production technology

The quality of carbon fibres, their strength and modulus of elasticity in particular can be increased by the following methods: decreasing the porosity of the initial PAN fibres by selecting the optimum conditions for spinning, plasticizing drawing, finishing, and drying; decreasing the inhomogeneity of the diameters of PAN fibres by suppressing deformation resonance during spinning by selecting conditions of jet formation and precipitation that do not allow formation of "bulbs" in the jets or prevent their deformation; decreasing fibril and crystallite size by reducing the precipitant and solvent concentration gradient in the precipitation zone (spinning in "mild" baths); creating optimum conditions for interphase self-ordering of the polymer at 450-550degreesC during precarbonization; increasing the cohesive energy by increasing the density to 1.75-2.10 g/cm(3). Substitution of convective tempering of PAN twists in thermooxidative treatment by conductive (contact) treatment decreases the duration of the treatment by 3-4 times and improves the environmental conditions. Use of reflecting screens in high-temperature furnaces reduces heat losses by 4-5 times and decreases consumption of cooling water The progress made in the technology and creation of high-capacity equipment suggests that the cost of high-strength carbon fibre will decrease to $10-15/kg in the future in the condition of large-scale production.