Synthesis and Properties of Melt Processable Acrylonitrile-N-vinylimidazole Copolymers and Fiber

Polyacrylonitrile (PAN) and acrylonitrile (AN) -N-vinylimidazole (VIM) copolymers [abbreviated as P(AN-co-VIM)] with various n(AN) : n((VIM) (93 : 7-80: 20) were synthesized by free-radical solution copolymerization in dimethyl formamide (DMF). The P (AN-co-VIM) copolymers (82 :18 and 80 : 20) possessed good melt processability, which were melt spun at the temperature of 210-220 degrees C. The crystallinity, thermodynamics behavior and the composition of P (AN-co-VIM) copolymers were studied and Characterized by ubbelodhe viscosimeter, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (H-1 NMR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analyses and hot stage microscope. The results revealed that P(AN-co-VIM) could be synthesized successfully by free-radical solution copolymerization. P(AN-co-VIM) could be melt processable as VIM molar fraction is higher than 10%. The melting temperature of P (AN-co-VIM) shifts continuously to the lower temperature with the comonomer contents increasing. When the molar fraction of VIM is increased to 20%, the melting point of P (AN-co-VIM) copolymer reduced from 317 degrees C to 180 degrees C. The highest decomposition temperature is 313.7 degrees C. The apparent morphology and mechanical properties of the P(AN-co-VIM) fibers were characterized by scanning electron microscope(SEM) and single fiber electronic tensile strength test. The results show that the fibers have smooth surface and compact cross section. As-spun P(AN-co-VIM) fiber gets the fracture strength of 1. 58 cN/dtex and the elongation at break attained 11. 2%. After post-treatment, the fiber is expected to be widely used in the field of carbon fiber.