Poly amorphous gauche

Poly(ethylene 2,6-naphthalate) (PEN) film containing alpha, beta and amorphous phases were prepared, and the amorphous contribution digitally subtracted to yield the characteristic spectra of the amorphous, alpha, and beta phases. In other words, the amorphous spectrum is determined by melting the polymer, so after subtraction, one knows the spectrum of all of them. The alpha crystal form adopts an all-rran conformation, while the beta crystal form adopts a conformation with appreciable gauche character. Conformational changes in PEN occur due to the rotation of the naphthalene ring as well as rotation of the ethylene glycol units. The normalised absorbances of the bands at 824 and 814 cm were correlated to polymer density, and can be used to represent the amorphous and alpha crystalline phases, respectively (56). 

The mechanical loading on a polymeric item not only changes its shape and sizes but also affect substantially its supramolecular structure. The mechanical loading on the amorphous-crystalline polymer (polyolefins) substantially influences first of all on the amorphous phase of the polymer. The stretching strain results in the conformational transitions the number of gauche conformations decreases and the number of trans conformations increases (polyethylene, poly(ethylene terephthalate)). Under strain chains of macromolecules are additionally oriented and the rotation of the rad-... 

Poly(l-butene) exists in three different helical conformations in the solid state [34] (Fig. 9.11). The CP-MAS spectra of the three crystalline polymorphs and the amorphous polymer of poly(l-butene) (Fig. 9.12) have been reported, and the spectra were interpreted by using a y-gauche shielding parameter that is dependent on the dihedral angle. The y-gauche shielding parameter is reduced to half its standard value when the angle is increased to 82 1°. 

Poly(oxymethylene) (POM) exists in two crystallographie forms a trigonal form with a 95 helical (all-gauche) eonformation and an orthorhombic form with a 21 helical conformation. The chemical shifts for the orthorhombic form are displaced upheld by about 2 ppm compared with the trigonal form [36]. The C-NMR spectrum of trigonal POM shows a sharp peak at 88.3 ppm, and the noncrystalline peak is displaced downheld to 89.6 ppm [37]. The crystalline and amorphous peaks can... 

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