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The analysis of the dielectric relaxations of two main chain liquid crystalline polymers, derived from hydroxybibenzoic acid and (R,S)- and (R)-2-methyl-1,3-propanediol, is reported. These polymers can be obtained in their glassy amorphous, glassy liquid crystalline or in the crystalline state depending on their thermal history. The effect of the morphology of the sample on the dielectric spectra...
Poly(trimethylene oxy-2 methyl trimethylene p–p′ bibenzoate) is a linear thermotropic liquid crystal polymer that may or may not develop anomalous orientation depending on the applied strain rate. X-ray diffraction patterns show that macromolecular chains tend to align perpendicularly to the deformation direction for the slowest analysed strain rates and in parallel to the deformation direction for...
The high temperature dielectric relaxation process, observed above the glass transition temperature in poly(ε-caprolactone) is studied by Thermally Stimulated Depolarization Currents experiments. The characterization is made by using the windowing polarization technique, decomposing the complex high temperature relaxation into Debye-like peaks. The profile of each peak is then analyzed by using a...
The relaxation behavior of high density polyethylene functionalized with diethylmaleate has been determined by dynamic mechanical method and thermally stimulated depolarization technique. The transitions observed have been related to the structural parameters as well as the α-olefin comonomer content and degree of grafting, and compared with previous TSDC results on LLPE functionalized with the same...
Restricted conformational transitions in oxyethylene chains have been investigated using a molecular mechanics approach. Geometries and energies of transition pathways have been evaluated for kink inversion and formation, and for crankshaft type motions which are feasible in anisotropic glassy matrices. Barrier heights for these processes are found to be similar to those determined for the corresponding...
The relaxations occurring in poly(triethylene oxide terephthaloyl bis(4-oxybenzoate)), PTrETOB, were studied by thermally stimulated depolarization currents technique (TSDC), and dynamic mechanical analysis (d.m.a.), and the results compared with those obtained by differential scanning calorimetry, thermo-optical analysis and wide angle X-ray diffraction. The low temperature relaxation observed by...
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