Melt-processable high acrylonitrile copolymers

High acrylonitrile homo- and copolymers (PAN) are unique because of chemical, ultraviolet, and corrosion resistances. Historically, because of the atypical processing and thermal behavior of solution-processable PAN, consensus regarding the actual microstructure and paracrystalline order was elusive -- it has been described as `two-dimensional liquid crystalline-like structure with many defects.' New, sequence-structured copolymers rendered PAN for the first time melt-processable before degradation and are providing new insight into the solid state conformation. Solution $^{13}$C nuclear magnetic resonance was used to compare the new and historical comonomer sequence lengths. Optimal processing conditions were obtained using capillary rheometry as a function of dwell time and melt temperature. A filament extrusion investigation was conducted and wide angle x-ray diffraction, differential scanning calorimetry thermograms and mechanical properties of the filaments were used to characterize the nonequilibrium melt transitions and paracrystal morphology as a function of processing parameters.