AB polybenzoxazole monomer

4 amino 3 hydroxybenzoic acid hydrochloride was synthezised from methyl(or ethyl)4 hydrobnezoate.High molecular weight poly benzoxazole (ABPBO)was synthesized through condensation polymerization of above monomer in poly (phosphoric acid).Apparent stiropalescene

the characteristic of lyotropic liquid crystal polymer

was observed at the later stage of the polymerization.ABPBO film was extruded and ABPBO fiber was spinned by dry jet wet spinning from ABPBO/PPA dope.Specific viscosity of ABPBO was measured in MSA.The structure of ABBBO films and fiber were studied by elemental analysis(EA)

X-ray photograph

X-ray diffraction

FTIR

TGA and Rheoribron.The tensile strength of ABPBO fiber is 1.44GPa

tensile modulus is 90GPa

and it begin to decompose at 657.3℃ in nitrogen

at 583.6℃ in air.It suggests that rigid lyotropic crystal ABPBO is a new kind of high performance polymer materials.