| 초록 |
Poly(p-phenylenebenzobisoxazole) (PBO) fibers are rigid-rod molecules with extended chain conformation. Fibers processed from PBO have very high tensile strength and tensile modulus, but their performance under compression have been disappointing. Poly(1,5-naphthalene-benzobisoxazole) (1,5-Naph-PBO) and Poly(2,6-naphthalene-benzobisoxazole) (2,6-Naph-PBO) are to convert phenylene into naphthalene. The determination of the crystalline structure of oriented fibers of 1,5-Naph-PBO and 2,6-Naph-PBO is described. Both unit cells are triclinic, with the parameters ; a=7.88Å, b=3.64Å, c=12.4Å, α=80.5o, β=116.4o and γ=105.8o for 1,5-Naph-PBO and a=6.63Å, b=3.49Å, c=14.15Å, α=76.73o, β=115o and γ=90o for 2,6-Naph-PBO. The fiber repeat consists in each structure of two fused ring guoups arranged in a planar, zigzag conformation. The conformational torsion angle within the unit cells are calculated from the Gaussian98 of the KISTI supercomputing center. The neighboring chains in the case of 1,5-Naph-PBO and 2,6-Naph-PBO are shifted by c/4 along the chain axis and assumed to arrange along the ıīo plane. |
