scholarly journals Structural Evolution Mechanism of Crystalline Polymers in the Isothermal Melt-Crystallization Process: A Proposition Based on Simultaneous WAXD/SAXS/FTIR Measurements

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1316 ◽  
Author(s):  
Tashiro ◽  
Yamamoto
Keyword(s):  
Spectral Data ◽  
Vinylidene Fluoride ◽  
Structural Evolution ◽  
Evolution Process ◽  
Helical Chain ◽  
Melt Crystallization ◽  
Time Resolved ◽  
X Ray ◽  
Crystalline Polymers ◽  
Polymer Species

Time-resolved simultaneous measurements of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) (and FTIR spectra) were performed for various kinds of crystalline polymers in isothermal melt-crystallization processes, from which the common features of the structural evolution process as well as the different behaviors intrinsic to the individual polymer species were extracted. The polymers targeted here were polyethylene, isotactic polypropylene, polyoxymethylene, aliphatic nylon, vinylidene fluoride copolymer, trans-polyisoprene, and poly(alkylene terephthalate). A universal concept of the microscopically viewed structural evolution process in isothermal crystallization may be described as follows: (i) the small domains composed of locally regular but more or less disordered helical chain segments are created in the melt (this important information was obtained by the IR spectral data analysis); (ii) these domains grow larger as the length and number of more regular helical segments increase with time; (iii) the correlation among the domains becomes stronger and they approach each other; and (iv) they merge into the stacked lamellar structure consisting of the regularly arranged crystalline lattices. The inner structure of the domains is different depending on the polymer species, as known from the IR spectral data

scholarly journals Elucidating the Structural Evolution of a Highy Porous Responsive Metal-Organic Framework (DUT-49(M)) upon Guests Desorption by Time-Resolved In-Situ Powder X-Ray Diffraction

2020 ◽  
Author(s):  
Bikash Garai ◽  
Volodymyr Bon ◽  
Francesco Walenszus ◽  
Azat Khadiev ◽  
Dmitri Novikov ◽  
...  
Keyword(s):  
Adsorption Isotherms ◽  
Metal Organic Framework ◽  
Structural Evolution ◽  
Structural Transformations ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Metal Organic ◽  
Subcritical Fluid

Variation in the metal centres of M-M paddle-wheel SBU results in the formation of isostructural DUT-49(M) frameworks. However, the porosity of the framework was found to be different for each of the structures. While a high and moderate porosity was obtained for DUT-49(Cu) and DUT-49(Ni), respectively, other members of the series [DUT-49(M); M= Mn, Fe, Co, Zn, Cd] show very low porosity and shapes of the adsorption isotherms which is not expected for op phases of these MOFs. Investigation on those MOFs revealed that those frameworks undergo structural collapse during the solvent removal at the activation step. Thus, herein, we aimed to study the detailed structural transformations that are possibly occurring during the removal of the subcritical fluid from the framework.

scholarly journals Microscopic identification of the order parameter governing liquid–liquid transition in a molecular liquid

2015 ◽  
Vol 112 (19) ◽  
pp. 5956-5961 ◽  
Author(s):  
Ken-ichiro Murata ◽  
Hajime Tanaka
Keyword(s):  
Order Parameter ◽  
Structural Evolution ◽  
Characteristic Size ◽  
Number Density ◽  
Time Resolved ◽  
X Ray ◽  
Molecular Liquid ◽  
X Ray Scattering ◽  
Liquid Transition ◽  
Scattering Measurements

A liquid–liquid transition (LLT) in a single-component substance is an unconventional phase transition from one liquid to another. LLT has recently attracted considerable attention because of its fundamental importance in our understanding of the liquid state. To access the order parameter governing LLT from a microscopic viewpoint, here we follow the structural evolution during the LLT of an organic molecular liquid, triphenyl phosphite (TPP), by time-resolved small- and wide-angle X-ray scattering measurements. We find that locally favored clusters, whose characteristic size is a few nanometers, are spontaneously formed and their number density monotonically increases during LLT. This strongly suggests that the order parameter of LLT is the number density of locally favored structures and of nonconserved nature. We also show that the locally favored structures are distinct from the crystal structure and these two types of orderings compete with each other. Thus, our study not only experimentally identifies the structural order parameter governing LLT, but also may settle a long-standing debate on the nature of the transition in TPP, i.e., whether the transition is LLT or merely microcrystal formation.

Structural Evolution of Aqueous Zirconium Acetate by Time-Resolved Small-Angle X-ray Scattering and Rheology

2015 ◽  
Vol 119 (22) ◽  
pp. 12660-12667 ◽  
Author(s):  
Martin Bremholm ◽  
Henrik Birkedal ◽  
Bo Brummerstedt Iversen ◽  
Jan Skov Pedersen
Keyword(s):  
Small Angle ◽  
Structural Evolution ◽  
Time Resolved ◽  
X Ray ◽  
Zirconium Acetate ◽  
X Ray Scattering ◽  
Ray Scattering

New Insight of Isothermal Melt Crystallization in Poly(aryl ether ether ketone) via Time-Resolved Simultaneous Small-Angle X-ray Scattering/Wide-Angle X-ray Diffraction Measurements

1995 ◽  
Vol 28 (20) ◽  
pp. 6931-6936 ◽  
Author(s):  
Benjamin S. Hsiao ◽  
Bryan B. Sauer ◽  
Ravi K. Verma ◽  
H. Gerhard Zachmann ◽  
Soenke Seifert ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Melt Crystallization ◽  
Aryl Ether ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ether Ether Ketone ◽  
Ether Ketone

Evaporation-induced structural evolution of the lamellar mesophase: a time-resolved small-angle X-ray scattering study

2019 ◽  
Vol 52 (5) ◽  
pp. 1169-1175 ◽  
Author(s):  
Jitendra Bahadur ◽  
Avik Das ◽  
Debasis Sen
Keyword(s):  
Structural Evolution ◽  
Water Molecules ◽  
Second Phase ◽  
Lamellar Thickness ◽  
Ambient Conditions ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Head Groups ◽  
Gel Phase

Time-resolved small-angle X-ray scattering (SAXS) measurements have been carried out using the newly developed SAXS beamline at the Indus-2 synchrotron source to study the evaporation-induced structural evolution of the lamellar mesophase. An aqueous dispersion of sodium dodecyl sulfate (SDS) of ∼0.60 volume fraction at room temperature results in a gel phase due to random jamming of the lamellar structured entities. Thermal analysis of SDS in the powder phase shows three distinct phenomena corresponding to evaporation of free and bound water, followed by thermal dissociation of SDS molecules. Time-resolved in situ SAXS measurements during evaporation of the gel under ambient conditions reveal two regimes of structural evolution of the lamellar phase. The evaporation rate in the first phase of evaporation up to 60 min is roughly six times faster than that in the second phase. A plausible mechanism is proposed to explain this behaviour. The intrusion of water molecules into layers sandwiched between polar head groups forms an additional 7 Å thick layer of water molecules, leading to an increase in the distance between the head groups. The evaporation of the water molecules in the first phase up to 60 min causes a reduction in the lamellar thickness of ∼3 Å. Subsequent evaporation of water molecules in the second phase is quite slow owing to the higher binding energy of these water molecules and the low permeability caused by the reduced lamellar thickness after the first phase of evaporation. The swelling behaviour of the lamellar structure under ambient conditions is found to be reversible and the powder-phase structure is observed after a few days of evaporation of the gel phase.

scholarly journals Phase Morphology and Molecular Structure Correlations in Model Fullerene-Polymer Nanocomposites

2012 ◽  
Vol 714 ◽  
pp. 63-66 ◽  
Author(s):  
David G. Bucknall ◽  
Gabriel Bernardo ◽  
Meisha L. Shofner ◽  
Deb Nabankur ◽  
Dharmaraj Raghavan ◽  
...  
Keyword(s):  
Polymer Nanocomposites ◽  
Vinylidene Fluoride ◽  
Acid Methyl Ester ◽  
Phase Morphology ◽  
X Ray ◽  
Crystalline Polymers ◽  
Acid Methyl ◽  
Structure Correlations ◽  
Poly Vinylidene Fluoride ◽  
Atactic Polystyrene

In this work we have performed a systematic study of blends of [6,-phenyl C61 butyric acid methyl ester (PCBM) with the following amorphous and semi-crystalline polymers: atactic polystyrene (PS), syndiotactic polystyrene (syn-PS), poly (2-vinyl-naphthalene) (P2VN), poly (9-vinyl-phenanthrene) (P9VPh), poly (vinylidene-fluoride) (PVdF) and poly (3-hexyl-thiophene) (P3HT). Experimental measurements using DSC, x-ray and neutron scattering coupled with molecular modeling (MD and DFT) have been utilized to determine the solubility and phase morphology of these model polymer-fullerene blends.

scholarly journals Structural evolution of high energy density V3+/V4+ mixed valent Na3V2O2x(PO4)2F3−2x (x = 0.8) sodium vanadium fluorophosphate using in situ synchrotron X-ray powder diffraction

2014 ◽  
Vol 2 (21) ◽  
pp. 7766-7779 ◽  
Author(s):  
Paula Serras ◽  
Verónica Palomares ◽  
Teófilo Rojo ◽  
Helen E. A. Brand ◽  
Neeraj Sharma
Keyword(s):  
Structural Evolution ◽  
High Energy ◽  
High Energy Density ◽  
Sodium Ion Battery ◽  
Time Resolved ◽  
X Ray ◽  
Xrd Study ◽  
First Time ◽  
Synchrotron Xrd

The first time-resolved in situ synchrotron XRD study of a cathode in a functioning sodium-ion battery. We determine the reaction mechanism, lattice parameters, sodium evolution, and the maximum sodium extraction for the fresh and precycled cell.

Structural Evolution of Amorphous Ge2Sb2Te5 Thin Films in the Transition to the Crystalline Phase

2008 ◽  
Vol 1072 ◽  
Author(s):  
Riccardo De Bastiani ◽  
Alberto Maria Piro ◽  
Maria Grazia Grimaldi ◽  
Emanuele Rimini ◽  
Giuseppe Baratta ◽  
...  
Keyword(s):  
Thin Films ◽  
Crystalline Phase ◽  
Short Range ◽  
Structural Modification ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Kinetics Of

ABSTRACTThe crystallization kinetics of as-deposited amorphous Ge2Sb2Te5 thin films has been measured by in situ time resolved reflectivity. X-ray diffraction and Raman scattering analyses of partially transformed samples allowed to correlate the evolution of the transition to the structural modification in the long and short range configuration. The experimental results evidenced that during the early stages of crystallization there is a reduction of Ge-Te tetrahedral bonds, characteristics of the Ge coordination in amorphous Ge2Sb2Te5 films.

Beyond structure: ultrafast X-ray absorption spectroscopy as a probe of non-adiabatic wavepacket dynamics

2016 ◽  
Vol 194 ◽  
pp. 117-145 ◽  
Author(s):  
Simon P. Neville ◽  
Vitali Averbukh ◽  
Serguei Patchkovskii ◽  
Marco Ruberti ◽  
Renjie Yun ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Absorption Spectroscopy ◽  
Vacuum Ultraviolet ◽  
Chemical Shifts ◽  
Structural Evolution ◽  
Time Resolved ◽  
X Ray ◽  
Wavepacket Dynamics ◽  
X Ray Absorption

The excited state non-adiabatic dynamics of polyatomic molecules, leading to the coupling of structural and electronic dynamics, is a fundamentally important yet challenging problem for both experiment and theory. Ongoing developments in ultrafast extreme vacuum ultraviolet (XUV) and soft X-ray sources present new probes of coupled electronic-structural dynamics because of their novel and desirable characteristics. As one example, inner-shell spectroscopy offers localized, atom-specific probes of evolving electronic structure and bonding (via chemical shifts). In this work, we present the first on-the-fly ultrafast X-ray time-resolved absorption spectrum simulations of excited state wavepacket dynamics: photo-excited ethylene. This was achieved by coupling the ab initio multiple spawning (AIMS) method, employing on-the-fly dynamics simulations, with high-level algebraic diagrammatic construction (ADC) X-ray absorption cross-section calculations. Using the excited state dynamics of ethylene as a test case, we assessed the ability of X-ray absorption spectroscopy to project out the electronic character of complex wavepacket dynamics, and evaluated the sensitivity of the calculated spectra to large amplitude nuclear motion. In particular, we demonstrate the pronounced sensitivity of the pre-edge region of the X-ray absorption spectrum to the electronic and structural evolution of the excited-state wavepacket. We conclude that ultrafast time-resolved X-ray absorption spectroscopy may become a powerful tool in the interrogation of excited state non-adiabatic molecular dynamics.

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