Interphase amorphous-crystalline phases

The half-widths of 37-39 and 78-88 Hz, respectively, for the crystalline and amorphous phases are significantly larger than 18 and 38 Hz for those of the bulk-crystallized linear polyethylene (cf. Table 1). This is caused by incorporation of minor ethyl branches. The molecular alignment in the crystalline phase is slightly disordered, and the molecular mobility in the amorphous phase will therefore be promoted. With broadening of the crystalline and amorphous resonances, the resonance of the interphase also widens in comparison to that of bulk-crystallized linear polyethylene samples. This shows that the molecular conformation is more widely distributed from partially ordered trans-rich, conformation to complete random conformation, characteristic as the transition phase from the crystalline to amorphous regions. 

The mass fraction of each phase that was obtained by the line shape analysis of the CH2 resonance line at different temperatures is summarized in Table 12 with Tic. It can be seen that the mass fraction of the crystalline phase (degree of crystallinity) stays unchanged at 0.57 over the wide temperature range from room temperature to 110 °C, while the amorphous phase increases and the interphase decreases with increasing temperature. The Tic of the CH2 carbon in each phase is mostly unchanged over the temperature range examined 65 70 s for the crystalline phase, 0.18 0.21 s for amorphous phase, and 7.0-7.5 s for the interphase. This shows that the molecular motion of each phase in the Tic time frame is almost the same either in the glassy or rubbery state. 

As pointed out above with relation to the data at 87 °C, the Tic of the crystalline-amorphous interphase is appreciably longer than that of the amorphous phase, suggesting the retention of the helical molecular chain conformation in the interphase. We also note that a Tic of 65-70 s for the crystalline phase is significantly shorter than that for other crystalline polymers such as polyethylene and poly-(tetramethylene oxide), whose crystalline structure is comprised of planar zig-zag molecular-chain sequences. In the crystalline region composed of helical molecular chains, there may be a minor molecular motion in the TiC frame, with no influence on the crystalline molecular alignment that is detected by X-ray diffraction analyses. Such a relatively short TiC of the crystalline phase may be a character of the crystalline structure that is formed by helical molecular chain sequences. 

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... 

The degree of molecular mobility in the interphase lies between that in the rigid crystalline phase and that in soft amorphous phase. The fraction of the intermediate phase was found to depends on the employed technique, the temperature and the method of data evaluation. In many respects, the intermediate phase has a kinetic origin and may not be regarded as a true thermodynamical phase. It would apparently be more correct to define the third phase as an interface or a semi-rigid fraction of the amorphous phase. 

However, in addition to the three phases indicated above, there are interphase zones which may contribute significantly to the gas permeation. The interphases that connect the crystalline PA phase to the amorphous PA phase and to the molten polyether phase could behave as a quasi-crystalline phase, or as a liquid-like phase. In polyethylenes, the constraints due to the crystallites reduce the molecular diffusion, and make it more selective [32]. In a recent study, we pointed out the significant contribution of these constrained interphases to the permeation in nanocomposite materials with a semi-crystalline polyamide 12 matrix [33]. Although the existence of such an interphase can be hardly proven, the result analysis based on the idea of coexistence of two amorphous fractions ( real ... 

The permeation of gases in such a complex structure is very difficult to model due to the lack of information on the phase structures and properties, as well as the complexity of such modelling. Qualitatively, the reduced mobility and the chain orientation in semi-ordered interphases due to the stiff and ordered crystallites would make the permeability smaller. For the Pebax grades with shorter polyether blocks and longer polyamide blocks, the tortuosity of the diffusion path will increase sharply when the polyether and amorphous PA phases become finely divided by the crystalhne phase. Nevertheless, we tried to use the PA phase crystallinity to simulate the CO2 and nitrogen permeabilities in Pebax films with the simple resistance model [35] to estimate the influence of the Pebax structure on the permeability. 

PP thus strength and heat resistance depend on the PE content [63,64]. Blends of PE and PP were immiscible in either the amorphous or the crystalline phase [65]. The two polymers tend to form mixtures of crystal structures, and each affects the crystallization of the other [66-70]. Studies on mechanical properties gave mixed results. Improvements in modulus, ultimate tensile strength, and heat deflection temperature [71] suggested good binding in the amorphous interphase [72] but use of HDPE to improve low temperature impact strength and environmental stress rack resistance required a compatibilizer such as 5% of ethylene-propylene rubber [42]. 

The temperature dependence of also shows additional inflections as a result of superposition of the relaxation processes associated with the glass transitions of the soft phase, the interphase, and the amorphous phase of the hard blocks, as well as with melting of the P04 block crystalline phase. The inflections of all curves at high temperatures, associated with the rapid decrease of modulus or increase of damping, characterize the softening point (plasticity),... 

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