Between 1977 and 1985, the Air Force Materials Laboratory funded a series of contracts, whereby Hoechst Celanese Research, formerly the Celanese Research Company, demonstrated and developed processes for the formation of fibers and films from highly viscous, anisotropic dopes of PBZT polymer. Heat treatment of these products was found to have significant effects on the tensile properties, and comparisons will be shown between asspun fibers and ones heat-treated at up to 1335°F (725°C).
In the later stages of the program, sufficient materials were produced to permit characterization of a broad range of properties. Some data on environmental resistance will be given. Fibers were incorporated into aerospace- grade epoxy resins for measurement of composite properties.
In summary, the results show that PBZT can be processed into fibers and films with improved mechanical properties and environmental resistance compared to aramids. A high degree of orientation of the rigid-rod molecules can be achieved which provides outstanding axial properties but this results in deficiencies in transverse properties and composite compression strength.