A new technique for the study of phase transitions by means of energy dispersive x-ray diffraction. Application to polymeric samples

Albertini, V. Rossi; Bencivenni, L.; Caminiti, Ruggero; Cilloco, F.; Sadun, Claudia

doi:10.1080/00222349608212381

Cited by 39 publications

(24 citation statements)

References 8 publications

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“…Molecular dynamics (MD), combined with large angle X‐ray scattering (LAXS) and with NMR spectroscopy, has recently been used by us for the determination of structural parameters (molecular assembly, interatomic and intermolecular distances) in the bulk,3, 12–14 and of stereochemistry in solution,15 respectively, of phosphazenic systems. Energy dispersive X‐ray diffraction (EDXD) is a LAXS modification that has been recognized to be useful for rapid derivation of the coherent scattering intensity curve 16–18…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics (MD) Simulations and Large‐Angle X‐ray Scattering (LAXS) Studies of the Solid‐State Structure and Assembly of Isotactic (R)‐Poly(2,2′‐dioxy‐1,1′‐binaphthyl‐)phosphazene in the Bulk State and in the Cast Film

Carriedo

Alonso

Alvarez

et al. 2004

Chemistry A European J

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The intrachain conformation, molecular structure and interchain assembly of isotactic (R)-poly(2,2'-dioxy-1,1'-binaphthyl)phosphazene (P-DBNP) both in the bulk state (I) and in the cast film (II) were studied by molecular dynamics (MD) simulations of models, as implemented by a bias potential for the analysis of the radial distribution function (RDF) obtained from large-angle X-ray scattering (LAXS) data. The microscopic structure and order extension of the polymer changed from I to II, as qualitatively shown in the shapes of their experimentally measured RDF curves. With the use of a bias potential, the MD simulations provided a much more accurate analysis of the models, as seen in the reproduction of the RDFs. The chiral P-DBNP chain was found to be consistent with helix conformations in both the I and the II samples. The predominant interchain clustering motif was best reproduced with a seven-chain model. In the case of I, the maximum chain length was 18 monomeric -R(2)NP- units, while in the case of the cast film II the chain was more elongated, up to distances of approximately 100 A, equivalent to over 48 monomeric -R(2)NP- units. The seven-chain assembly was accounted for in terms of nonbonded interactions favouring the minimum voids area between the seven tubular structures of the material. The results validate our earlier finding that MD analysis with implementation of a biasing potential for the RDFs can provide quantitative information on the structural and conformational features of amorphous solids. The combined theoretical and experimental approach was found to be a useful tool to detect, locate and evaluate the intra- and intermolecular modifications of materials subsequent to their phase transformation and, as in the present case, changes in their microscopic structures or preparation methods.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics (MD) Simulations and Large‐Angle X‐ray Scattering (LAXS) Studies of the Solid‐State Structure and Assembly of Isotactic (R)‐Poly(2,2′‐dioxy‐1,1′‐binaphthyl‐)phosphazene in the Bulk State and in the Cast Film

Carriedo

Alonso

Alvarez

et al. 2004

Chemistry A European J

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“…The X-ray experiments (WAXS) were carried out on a new energy-dispersive diffractometer recently set up in our lab at the University "La Sapienza" of Rome. The instrument has a novel horizontal design that allows to perform the data acquisitions at the three/four xed angular congurations needed by the technique [55][56][57] very rapidly and at large momentum transfer range (0.5-24Å À1 ). Owing to the marked increase of the intensity, in fact, a complete diffraction pattern (see below) at high statistics viz.…”

Section: Methodsmentioning

confidence: 99%

Bio ionic liquids and water mixtures: a structural study

et al. 2017

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“…The temperature range explored was 25–140 °C at a heating rate of 0.1 K min −1 . The diffraction experiments were carried out in transmission geometry by using an energy‐dispersive X‐ray diffractometer assembled in our laboratory22 on a Seifert and Rich high‐voltage power supply, whose stability is better than 0.1%. A diffraction angle of 5° was used, corresponding to 1 < q < 4 Å −1 and allowing the observation of the main diffraction peaks.…”

Section: Methodsmentioning

confidence: 99%

Poly(p‐phenylene sulfide) nonisothermal cold‐crystallization

Martinelli

D’Ilario

Caminiti

2005

J Polym Sci B Polym Phys

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The poly(p-phenylene sulfide) (PPS) nonisothermal cold-crystallization behavior was investigated in a wide heating rate range. The techniques employed were the usual Differential Scanning Calorimetry (DSC), and the less conventional FT-IR spectroscopy and Energy Dispersive X-ray Diffraction (EDXD). The low heating rates (Phi) explored by EDXD (0.1 K min(-1)) and FT-IR (0.5-10 K min(-1)) are contiguous and complementary to the DSC ones (5-30 K min(-1)). The crystallization temperature changes from 95 degrees C at Phi = 0.05 K min(-1) to 130 degrees C at Phi = 30 K min(-1). In such a wide temperature range the Kissinger model failed. The model is based on an Arrhenius temperature dependence of the crystallization rate and is widely employed to evaluate the activation energy of the crystallization process. The experimental results were satisfactorily fit by replacing in the Kissinger model the Arrhenius equation with the Vogel-Fulcher-Tamann function and fixing U* = 6.28 k J mol(-1), the activation energy needed for the chains movements, according to Hoffmann. The temperature at which the polymer chains are motionless (T-infinity = 42 degrees C) was found by fitting the experimental data. It appears to be reasonable in the light of our previously reported isothermal crystallization results, which indicated T-infinity = 48 degrees C. Moreover, at the lower heating rate, mostly explored by FT-IR, a secondary stepwise crystallization process was well evidenced. In first approximation, it contributes to about 17% of the crystallinity reached by the sample. (c) 2005 Wiley Periodicals, Inc

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A new technique for the study of phase transitions by means of energy dispersive x-ray diffraction. Application to polymeric samples

Cited by 39 publications

References 8 publications

Molecular Dynamics (MD) Simulations and Large‐Angle X‐ray Scattering (LAXS) Studies of the Solid‐State Structure and Assembly of Isotactic (R)‐Poly(2,2′‐dioxy‐1,1′‐binaphthyl‐)phosphazene in the Bulk State and in the Cast Film

Molecular Dynamics (MD) Simulations and Large‐Angle X‐ray Scattering (LAXS) Studies of the Solid‐State Structure and Assembly of Isotactic (R)‐Poly(2,2′‐dioxy‐1,1′‐binaphthyl‐)phosphazene in the Bulk State and in the Cast Film

Bio ionic liquids and water mixtures: a structural study

Poly(p‐phenylene sulfide) nonisothermal cold‐crystallization

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