A rigid-rod dihydroxy poly(p-phenylene benzobisoxazole) fiber with improved compressive strength

A series of dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO) were prepared by introducing binary hydroxyl groups, that is 2,5-dihydroxyterephthalic acid (DHTA) into poly(p-phenylene benzoxazole) (PBO) macromolecular chains and then DHPBO fibers were prepared by dry-jet wet-spinning method. As indicated by Fourier transform infrared spectrum (FTIR), hydroxyl groups were incorporated into DHPBO polymer chains successfully and intermolecular hydrogen-bonds had been formed. The effects of hydroxyl groups on the compressive property of PBO fibers were investigated by elastic loop test method. The test results showed that the compressive strength of DHPBO fibers with 10 mol% DHTA content were obviously higher than that of PBO fibers.