MAGNETIC ALIGNMENT AND CRYSTALLIZATION BEHAVIOR OF ISOTACTIC POLYSTYRENE

摘要

Magnetic alignment and crystallization behavior of isotactic polystyrene (iPS) was studied using DSC, POM, FT-IR, and birefringence measurements. The onset temperature for crystallization during the cooling process depended on the melting temperature. From observations using a polarized optical microscope, the number of spherulites decreased when melting occurred at temperatures greater than 265 ℃. These results suggested that melt memory effect existed in iPS when melting at under 265 ℃. The maximum value of transmitted light intensity observed by birefringence measurements depended on the melting temperature. The high nucleation density obtained by melting under 265 ℃ was suitable to achieve a higher orientation. In-situ infrared measurements in a magnetic field have been made in a home-built apparatus, in which an autorotation polarizer unit was installed to simultaneously obtain automatically polarized infrared spectra that are both parallel and perpendicular to the magnetic field. Orientation was confirmed for a crystalline band, while no orientation was confirmed for an amorphous band. The dichroic difference increased with increasing crystallinity during isothermal crystallization. In the present study, orientation was not observed in the melting state.