Rigid-rod Benzobisazole Polymers Containing Benzothiazole Pendent Groups

Abstract

Novel polybenzobisazoles containing benzothiazole pendent groups were prepared by the reaction of 2-benzothiazole or 2,5-dibenzothiazole terephthalic acids with the appropriate aminomercapto, aminohydroxy or tetraamino -nonomers in poly phosphoric acid at elevated temperatures. The polymerizations were carried out at concentrations (10-18%) which would promote anisotropic reaction mixtures. Intrinsic viscosities in the range of 4-19 dl/g were measured in methanesulfonic acid at 30°C. Thermogravimetric-mass spectral analysis in vacuo showed that the pendent benzothia zole group was the initial product of thermal degradation, maximizing at 590°C. Anisotropic polymerization mixtures could be wet-spun into fibres with modulus values between 25-30 Msi and tenacity values up to 350 Ksi.