延伸ポリプロピレンフィルム内の分散染料拡散と二色性配向係数

抄録

Diffusion of a disperse dye (C. I. Disperse Yellow 7) in polypropylene film was studied in the absence of water by a desorption sublimation method at 100°C. The films were stretched at 130 or 140°C in polyethyleneglycol and subsequently heat-treated with or without restraint at 150°C, and or immersed in cyclohexane at 68°C. Dichroic orientation factor (f_D) of the films dyed with the same dye was used as an orientation parameter and its effect on the diffusion coefficient (D) was studied. One found that D was monotonically decreased with increasing draw ratio (v) or f_D, where the D vs. v plots were curves convex toward the v axis, while the D vs. f_D plots were comparatively linear; it is suggested that the dye diffusion process is more directly associated with the orientation of the amorphous region in which the dye molecule penetrates. D of the variously treated films with equal value of f_D (0.37-0.40) decreases in the order from the swollen film to the heat-treated one with constraint, and a good linear relationship between log D and log E'' (loss modulus) was observed within some of the samples including above films with equal f_D value. It is explained that, even though the films have the same degree of amorphous chain orientation, free volume produced by segmental motions in oriented samples varies as a change of effective amorphous chain length which may be resulted in partial melting of metastable quasicrystallites by heat-treatment or swelling, and hence the diffusivity of the dye also changes among these samples.