scholarly journals Assessing Fast Structure Formation Processes in Isotactic Polypropylene with a Combination of Nanofocus X-ray Diffraction and In Situ Nanocalorimetry

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2652
Author(s):  
Yaroslav Odarchenko ◽  
Martin Rosenthal ◽  
Jaime J. Hernandez ◽  
David Doblas ◽  
Emanuela Di Di Cola ◽  
...  
Keyword(s):  
Structure Formation ◽  
Isotactic Polypropylene ◽  
Crystallization Temperature ◽  
Alpha Phase ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Nucleation Time ◽  
Continuous Growth ◽  
X Ray

A combination of in situ nanocalorimetry with simultaneous nanofocus 2D Wide-Angle X-ray Scattering (WAXS) was used to study polymorphic behaviour and structure formation in a single micro-drop of isotactic polypropylene (iPP) with defined thermal history. We were able to generate, detect, and characterize a number of different iPP morphologies using our custom-built ultrafast chip-based nanocalorimetry instrument designed for use with the European Synchrotron Radiation Facility (ESRF) high intensity nanofocus X-ray beamline facility. The detected iPP morphologies included monoclinic alpha-phase crystals, mesophase, and mixed morphologies with different mesophase/crystalline compositional ratios. Monoclinic crystals formed from the mesophase became unstable at heating rates above 40 K s−1 and showed melting temperatures as low as ~30 K below those measured for iPP crystals formed by slow cooling. We also studied the real-time melt crystallization of nanogram-sized iPP samples. Our analysis revealed a mesophase nucleation time of around 1 s and the co-existence of mesophase and growing disordered crystals at high supercooling ≤ 328 K. The further increase of the iPP crystallization temperature to 338 K changed nucleation from homogeneous to heterogeneous. No mesophase was detected above 348 K. Low supercooling (≥ 378 K) led to the continuous growth of the alpha-phase crystals. In conclusion, we have, for the first time, measured the mesophase nucleation time of supercooled iPP melted under isothermal crystallization conditions using a dedicated experimental setup designed to allow simultaneous ultrafast chip-based nanocalorimetry and nanofocus X-ray diffraction analyses. We also provided experimental evidence that upon heating, the mesophase converts directly into thermodynamically stable monoclinic alpha-phase crystals via perfection and reorganization and not via partial melting. The complex phase behaviour of iPP and its dependence on both crystallization temperature and time is presented here using a time–temperature–transformation (TTT) diagram.

Time-resolved in situ X-ray diffraction study of MCM-41 structure formation from a homogeneous environment

1999 ◽  
Vol 1 (12) ◽  
pp. 3053-3057 ◽  
Author(s):  
Jiří Rathouský ◽  
Günter Schulz-Ekloff ◽  
Jiří Had ◽  
Arnošt Zukal
Keyword(s):  
Diffraction Study ◽  
Structure Formation ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Mcm 41 ◽  
Homogeneous Environment

Tautomeric polymorphism of the neuroactive inhibitor kynurenic acid

2019 ◽  
Vol 75 (6) ◽  
pp. 793-805
Author(s):  
Dorota Pogoda ◽  
Jan Janczak ◽  
Sylwia Pawlak ◽  
Michael Zaworotko ◽  
Veneta Videnova-Adrabinska
Keyword(s):  
Solid State ◽  
Kynurenic Acid ◽  
Variable Temperature ◽  
Neurological Diseases ◽  
Crystal Form ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Kynurenic acid (KYN; systematic name: 4-hydroxyquinoline-2-carboxylic acid, C10H7NO3) displays a therapeutic effect in the treatment of some neurological diseases and is used as a broad-spectrum neuroprotective agent. However, it is understudied with respect to its solid-state chemistry and only one crystal form (α-KYN·H2O) has been reported up to now. Therefore, an attempt to synthesize alternative solid-state forms of KYN was undertaken and six new species were obtained: five solvates and one salt. One of them is a new polymorph, β-KYN·H2O, of the already known KYN monohydrate. All crystal species were further studied by single-crystal and powder X-ray diffraction, thermal and spectroscopic methods. In addition to the above methods, differential scanning calorimetry (DSC), in-situ variable-temperature powder X-ray diffraction and Raman microscopy were applied to characterize the phase behaviour of the new forms. All the compounds display a zwitterionic form of KYN and two different enol–keto tautomers are observed depending on the crystallization solvent used.

In Situ Reflection High-Energy Electron Diffraction Study of Structure and Morphology Evolution of AlN Thin Films During Growth

1996 ◽  
Vol 449 ◽  
Author(s):  
F. Jin ◽  
G. W. Auner ◽  
R. Naik ◽  
P. Zatyko ◽  
U. Rao
Keyword(s):  
Electron Diffraction Study ◽  
High Energy ◽  
X Ray Diffraction ◽  
Continuous Growth ◽  
X Ray ◽  
Structure And Morphology ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Growth Methods

ABSTRACTAIN films were grown on Si (111) substrates using a PSMBE deposition system. Two types of growth methods were used: (i) a continuous growth at one temperature and (ii) a two stage growth where a buffer layer at low temperature is followed by deposition at higher temperature. The structure and morphology of the films grown at different temperatures are compared. The evolution of surface structure and morphology of the film during the growth were studied using in-situ RHEED, X-ray diffraction, and AFM.

In Situ FTIR Spectroscopy Study on the Crystallization Process of Isotactic Polypropylene in Isotactic Polypropylene/Polyethylene-Glycol Blends

2012 ◽  
Vol 476-478 ◽  
pp. 2223-2226 ◽  
Author(s):  
Xiu Yun Li ◽  
Li Yang ◽  
De Chun Liu
Keyword(s):  
Polyethylene Glycol ◽  
Isotactic Polypropylene ◽  
Crystallization Process ◽  
Helical Structure ◽  
Spectroscopy Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Onset Crystallization Temperature ◽  
Variation Tendency

The crystallization of isotactic polypropylene (iPP) and polypropylene/polyethylene-glycol （iPP/PEG） blends were investigated by in situ Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). It was found that the existence of polyethylene-glycol（PEG） does not destroy the helical structure of iPP in the melt, but changes the crystal structure of iPP in the bends. Moreover, the variation tendency of ratios of intensity A998 cm-1/A1460 cm-1 for iPP and iPP/PEG blends showed that the the onset crystallization temperature of iPP is improved by addition of PEG until the PEG content reaches to 5 wt%, and beyond this content, the crystallization point decreases.

scholarly journals In situ phase behaviour of a high capacity LiCoPO4 electrode during constant or pulsed charge of a lithium cell

2016 ◽  
Vol 52 (98) ◽  
pp. 14169-14172 ◽  
Author(s):  
Michael G. Palmer ◽  
James T. Frith ◽  
Andrew L. Hector ◽  
Andrew W. Lodge ◽  
John R. Owen ◽  
...  
Keyword(s):  
High Capacity ◽  
Phase Changes ◽  
Phase Behaviour ◽  
Pulsed Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lithium Cell

The phase changes that occur during lithium extraction from LiCoPO4 under constant or pulsed current were studied using synchrotron X-ray diffraction.

scholarly journals In situ observations of the mesophase formation of isotactic polypropylene—A fast time-resolved X-ray diffraction study

2011 ◽  
Vol 44 (1) ◽  
pp. 95-101 ◽  
Author(s):  
Koji Nishida ◽  
Kazuma Okada ◽  
Harutoshi Asakawa ◽  
Go Matsuba ◽  
Kazuki Ito ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Isotactic Polypropylene ◽  
Fast Time ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Mesophase Formation ◽  
In Situ Observations

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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