DYE DESORPTION BEHAVIOR OF POLYPROPYLENE AND POLYSTYRENE

The following samples of polypropylene and polystyrene were prepared. Disperse dye (1, 4-diamino anthraquinone) was sandwiched between two films and hot-pressed, and then quenched (quenched film) or cooled gradually (annealed film). Quenched film was heat-treated at 150°C for 5 hr (heat-treated film). The dye desorption in boiling water for above samples was measured.For polystyrene, the desorption rate was very low, and slightly differed by the dye content, the hotpressed temperature and the hot-pressed time. The crystallization of dye molecule was recognized by X-ray measurement for heat-treated film and annealed film, and the desorption rate of these films increased. For polypropylene, dye content available for desorption increased and the desorption rate decreased by increasing the hot-pressed time and the hot-pressed temperature. By annealing, the crystallinity measured by densitymethod increased and the desorption rate decreased. The value of the diffusion constant in desorption for polypropylene is 200 times larger than that for polystyrene, and is nearly half of that in absorption for polypropylene. Some discussion was made on these dye desorption behaviors.