SPP/o-dichlorobenzene gel

Fig. 27. Equilibrium DD/MAS 13C NMR spectrum of sPP/o-dichlorobenzene gel (13.6 wt%), obtained by a n/2 single pulse sequence with a repetition time of 300 s. In the lower part the equilibrium spectrum of the bulk sPP crystal in ttgg form is shown for reference. The arrows indicate the resonance of the amorphous component of each carbon...

Fig. 29. IR spectra of the tttt and ttgg bulk crystals and sPP/o-dichlorobenzene gel (13.6 wt%). The spectrum of the gel represents only the contribution from the sPP polymer that was obtained by subtracting the contribution from the solvent...

Fig. 30. Line shape analyses of the resonance lines of methine and methyl carbons in sPP/o-dichlorobenzene gel. A, B, and C indicate the crystalline, amorphous, and crystalline-amorphous interfacial components, respectively. (This figure was obtained by revising Fig. 7 in Ref. 25 whose horizontal chemical shift axis was somewhat shifted)...

As can be seen from the Table 15, 70 and 30% of the solvent are respectively in the bound and free state. The mass fractions of the bound and free solvents are in rough accordance with those of the crystalline-amorphous interphase and the amorphous phase in the two noncrystalline phases of the polymer. This result suggests that the solvent exists in the two noncrystalline phases of the polymer, as the bound solvent in the crystalline-amorphous interphase and as the free solvent in the amorphous phase, leaving the crystalline phase pure. It is concluded that the sPP/o-dichlorobenzene gel involves three phases, (1) the pure crystalline... 

Since two resonance lines at 39.0 and 47.7 ppm that correspond to those observed in the ttgg form and a resonance line at 49.0 ppm that corresponds to that in the tttt form are recognized in the gel spectrum, a coexistence of these two forms in the gel might be supposed. In an attempt to determine the possibility of the coexistence of the two forms in the gel, we measured the IR spectrum that is sensitive to the molecular conformation. The number of normal vibrational modes depends sensitively on the molecular conformation based on the selection rule of the symmetry species. Kobayashi et al. confirmed the vibrational modes assignable to the ttgg conformation in the IR spectrum for the gel from a sPP/carbon disulfide system [117]. However, since we used o-dichlorobenzene as solvent, we examined whether the gel structure depends on the solvent. 

Phase Structure as Revealed from the Mobility of the Solvent. The phase structure of the sPP crystal in the gel form, which was elucidated by the line-decomposition analysis of the DD/MAS 13C NMR spectrum, will reflect on the mobility of the solvent in the gel. The mobility of the solvent can be examined by the longitudinal relaxation of resonance lines assigned to the carbons of the solvent. Figure 31 shows the longitudinal relaxation for the line at 130 ppm of the o-dichlorobenzene. The open circles indicate the data of the pure solvent and the closed ones those of the solvent in the gel. As can be seen, the relaxation of the pure solvent evolves exponentially with a Tic of 3.0 s, whereas that of the solvent in the gel evolves nonexponentially. This indicates that there are some solvent molecules in the gel that differ in their mobility. We assume here that the longitudinal relaxation of each component of the solvent evolves exponentially. Then the longitudinal relaxation of the total solvent follows the relationship ... 

---