A process is disclosed for the production of biaxially oriented liquid crystal films. The process comprises:(i) forming an anisotropic dope from a polymerization solution of rigid rod heterocyclic liquid crystalline polymers such as poly{[benzo(1,2-d:4,5-d′)bisthiazole-2,6-diyl] 1,4 - phenylene}, its cis isomer or mixtures thereof, and poly{[benzo(1,2-d:4,5-d′)bisoxazole-2,6-diyl] 1,4-phenylene}, its cis isomer or mixtures thereof, and a solvent such as polyphosphoric acid;(ii) extruding the dope to form a film;(iii) imparting biaxial orientation to the film to increase the transverse strength thereof;(iv) solidifying the biaxially oriented film; and(v) washing the solidified film to remove the solvent. Also disclosed is a liquid crystal film produced by the above process.展开▼
