Polyethylene liquid-like amorphous phase

Our broad-line XH NMR analysis showed that this type of sample generally consists of the phase structure of lamellar crystallites and noncrystalline overlayer with a negligible amount of the noncrystalline amorphous phase [16,62]. In broad-line H NMR spectra of solution-grown linear polyethylene samples, a narrow component that suggests the existence of a liquid-like amorphous phase is hardly recognized. In Table 2, the three-component analysis of the broad-line XH NMR spectra of linear polyethylene samples with different molecular weights that were crystallized isothermally from 0.08% toluene solution at 85 °C for 24 hours under a nitrogen atmosphere is summarized. 

To elucidate the phase structure in detail it is necessary to characterize the molecular chain conformation and dynamics in each phase. However, it is rather difficult to obtain such molecular information, particularly of the noncrystalline component, because it is substantially amorphous. In early research in this field, broad-line H NMR analysis showed that linear polyethylene crystallized from the melt comprises three components with different molecular mobilities solid, liquid-like and intermediate molecular mobility [13-16]. The solid component was attributed to molecules in the crystalline region, the liquid component to... 

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 ... 

---