ABSTRACT
The surface state of a semicrystalline polymer, according to the three-phase model of semicrystalline polymers, consists of (1) a crystalline phase, (2) an amorphous (noncrystalline) phase, and (3) the transition phase between crystalline and amorphous phases. The macromolecules in the crystalline phase are considered immobile. The macromolecules in the amorphous phase are mobile, depending on (TTg). The macromolecules in the transitional phase have restricted mobility due to the tie molecules to the crystalline phase. The transitional phase does not extend far from the surfaces of crystals, but the volume fraction of the transitional phase, though small, is proportional to the volume fraction of the crystalline phase. Thus, the higher the crystallinity, the higher is the effect of the transitional phase. The most widely used two-phase model ignores the presence of the transitional phase. However, for the integrity of the surface state, the role of the transitional phase seems to be very important because molecules cannot move as freely as in the amorphous phase (highly restricted mobility) but do not have well-assembled matrix as in the crystalline phase. Accordingly, the transitional phase acts as the weak boundary in the surface state.
