Magnetic Orientation of Crystalline Polymers in View of Liquid Crystallinity during Induction Period of Crystallization

Magnetic orientation of poly(ethylene-2,6-naphthalate) (PEN) and isotactic polystyrene (iPS) has been reported. The orientation starts to occur during the induction period of isothermal melt crystallization process, i.e. during the initial stage of crystallization process where no crystal growth is yet observed with respect to the wide angle X-ray diffraction. In the case of PEN, the crystallites obtained at later stages of crystallization were aligned with its c-axis parallel to the magnetic field, while in the case of iPS, the crystallites obtained were aligned with its c-axis perpendicular to the magnetic field. X-ray, infrared, and magnetic birefringence measurements indicated that mesophases appearing during the induction period could be responsible for the magnetic orientation of these polymers.