1,721,230 research outputs found
Characterization of Syndiotactic Polystyrene Nanofilms by PM-IRRAS Spectroscopy
No full textSummary Nano syndiotactic polystyrene (s-PS) films prepared by casting and spin-coating of diluted solutions have been characterized by Polarization Modulated Infra-red Reflection Absorption Spectroscopy (PM-IRRAS). In this work it will be shown that PM-IRRAS allows a complete characterization of s-PS nanofilms polymorphism. In particular PM-IRRAS is not only capable to investigate the polymeric chain conformational ordering but is also sensible to the crystalline chain packing. It will be also shown that PM-IRRAS allows the study of uniplanar orientation obtained in s-PS nanofilms
Thermal Behaviour of Syndiotactic Polystyrene Gels and Stoichiometry of Polymer-Solvent Compounds
No full textThe phase behavior of syndiotactic polystyrene (sPS)/1,2-dichloroethane (DCE) gels has been investigated by differential scanning calorimetry (DSC) and wide angle x-ray diffraction (WAXD) for different gel formation conditions. DSC data
show that the gel melting temperatures are independent of the cooling conditions leading to gel formation, whereas the melting enthalpies of the gels depend on the cooling history. WAXD measurements show that for low concentration gels the sPS/DCE clathrate structure is obtained, whereas for high concentration gels
both the clathrate structure and the solvent-free b phase can be obtained. Furthermore, the onset of formation of the b phase is dependent on the cooling rate. In light of combined DSC and WAXD data, the reliability of the DSC in evaluating the absolute stoichiometry of polymer-solvent compounds formed in sPS/DCE
gels is discussed
Nanoporous Crystalline Polymer Materials for Environmental Applications
No full textNanoporous crystalline phases can be obtained with syndiotactic polystyrene (s-PS) and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) materials characterized by a large variety of morphologies such as film, powder, or aerogel.
These nanoporous crystalline materials are characterized by a high sorption capacity of volatile organic compounds (VOC) also when present in traces in air and water and thus are potentially interesting for environmental applications such as air/water purification. Different aspects relative to the structure and the sorption properties of these innovative polymeric materials are presented in this report
Rev. Daniel Christophe Fives, The use of the optative Mood in the works of Theodoret, bishop of Cyrus (The catholic University of America patristic Studies, vol. L), 1937
No full textJuret A. Rev. Daniel Christophe Fives, The use of the optative Mood in the works of Theodoret, bishop of Cyrus (The catholic University of America patristic Studies, vol. L), 1937. In: Revue des Études Anciennes. Tome 40, 1938, n°1. p. 96
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