1408 M.C. Paiva et al. Carbon 41(2003)1399-1409 a)As spun fibe c) Heat oxidized fibe 300 %o stra b) uv irradiated fibers d)Carbonized fibers M 100 %o strain Y strain Fig. 10. The effect of UV irradiation, thermal oxidation, and carbonization on the tensile properties of M and VT fibers properties of the carbon fibers obtained. Comparison of the Acknowledgements mechanical properties of M. Ma and M, shows that this conclusion is valid for fibers stabilized at constant load as The authors well as constant length. from the Department of Energy, through grant No 4500011036 work made use of erc shared Facilities supported by the National Sc cience under Award No. EEC-9731680 5. Conclusions This study establishes the feasibility of producir References carbon fibers from melt-spinnable polyacrylonitrile co- olymers. DSC and solubility tests performed on PAN- [l Grassie N, Hay JN, McNeill IC. Thermal coloration and ret-spun fibers and on experimental melt-spun fib insolubilization in polyacrylonitr showed that UV irradiation effectively crosslinked the copolymers to an extent that enabled subsequent thermal 22] Edie DD. The effect of processing on the structure and oxidation. The experimental fibers could also be success- properties of carbon fibers. Carbon 1998, 36(4): 345-62 ly carbonized. Although the carbon fibers exhibited low 3]Davidson JA, Jung H-T, Hudson SD, Percec S Investigation mechanical properties, there is a potential to substantially f molecular orientation in melt-spun high acrylonitrile fibers, Polymer 2000, 41: 3357-64 improve these properties by optimizing polymer structure 4 Jokarsky R, Ball LE, Wu MM, Uebele CE. Melt spun (copolymer composition and molecular weight) and melt rylonitrile olefinically unsaturated fibers and a process to pinning conditions to form smaller diameter precursor make fibers. US Pat 6, 114, 034(2000) fibers with higher degrees of molecular orientation 5] Brandrup J, Peebles Jr. LH. On the chromophore of poly1408 M.C. Paiva et al. / Carbon 41 (2003) 1399–1409 Fig. 10. The effect of UV irradiation, thermal oxidation, and carbonization on the tensile properties of M and VT fibers. properties of the carbon fibers obtained. Comparison of the Acknowledgements mechanical properties of M M and M shows that this a, d 2 conclusion is valid for fibers stabilized at constant load as The authors gratefully acknowledge the financial support well as constant length. from the Department of Energy, through grant No. 4500011036. This work made use of ERC Shared Facilities supported by the National Science Foundation under Award No. EEC-9731680. 5. Conclusions This study establishes the feasibility of producing References carbon fibers from melt-spinnable polyacrylonitrile co￾polymers. DSC and solubility tests performed on PAN- [1] G rassie N, Hay JN, McNeill IC. Thermal coloration and based wet-spun fibers and on experimental melt-spun fibers insolubilization in polyacrylonitrile. J Polym Sci 1962;56:189–202. showed that UV irradiation effectively crosslinked the [2] E die DD. The effect of processing on the structure and copolymers to an extent that enabled subsequent thermal properties of carbon fibers. Carbon 1998;36(4):345–62. oxidation. The experimental fibers could also be success- [3] D avidson JA, Jung H-T, Hudson SD, Percec S. Investigation fully carbonized. Although the carbon fibers exhibited low of molecular orientation in melt-spun high acrylonitrile mechanical properties, there is a potential to substantially fibers. Polymer 2000;41:3357–64. improve these properties by optimizing polymer structure [4] J okarsky RJ, Ball LE, Wu MM, Uebele CE. Melt spun (copolymer composition and molecular weight) and melt acrylonitrile olefinically unsaturated fibers and a process to spinning conditions to form smaller diameter precursor make fibers. US Pat 6,114,034 (2000). fibers with higher degrees of molecular orientation. [5] B randrup J, Peebles Jr. LH. On the chromophore of poly-