Processing, structure and mechanics of fibres of heteroaromatic oxazole polymers

An analysis of deformation process on poly-p-phenylenebenzobisoxazole fiber and a structural study of the new high-modulus type PBO HM+ fiber

“…1). In general the fiber modulus for these super fibers is controlled by molecular orientation; 5,6 it has already been found that the HM fiber takes highly oriented molecular structure, which exceeds poly-p-phenylene terephthalamide (p-Aramid). 3 But it was also confirmed by using a small-angle X-ray scattering (SAXS) method that the HM fiber includes periodical density fluctuation along the fiber axis.…”

A Novel Random Preferential Orientation of the Crystal A‐axis Along the Radial Direction Confirmed on the Poly‐<i>p</i>‐phenylenebenzobisoxazole (PBO) Fiber Made with a Water

“…The fiber can be spun from dope (concentrated solution) made from PBO molecules and poly-phosphoric acid, then coagulated, washed, dried and heat-treated if necessary. Because the PBO molecule take a relatively straight conformation in the fiber, the molecular orientation is proved to be very high along the fiber axis, whereas the interaction between molecules normal to the fiber direction is not so strong [4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Therefore, the fiber shows relatively small crystallite size, especially along the a-and b-axes.…”

The Effect of Non-Aqueous Coagulation in the Structure of Poly-<i>p</i>-phenylenebenzobisoxazole (PBO) Fibers

“…To improve this mechanical properties much higher, we have been looking into the structural formation of fiber during coagulation and found that a non-aqueous coagulant gives a different fiber structure 1 . The fiber is expected to have a higher molecular orientation with less structural inhomogeneity along the fiber axis, which has been revealed by small and wide-angle X-ray diffraction (SAXS and WAXS) techniques and high-resolution transmission electron microscope (HREM) observation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Figure 1 shows the relationship between fiber modulus and the crystallite orientation of the (200) diffraction of the PBO crystal estimated by X ray, in which the three fibers show high molecular orientation to the fiber axis than other conventional fibers 19 .…”