scholarly journals c-Perpendicular Orientation of Poly(ʟ-lactide) Films

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1572
Author(s):  
Baku Nagendra ◽  
Paola Rizzo ◽  
Christophe Daniel ◽  
Lucia Baldino ◽  
Gaetano Guerra
Keyword(s):  
Low Temperature ◽  
Film Plane ◽  
Wide Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Amorphous Films ◽  
High Transparency ◽  
X Ray ◽  
Crystalline Forms ◽  
Induced Crystallization

Poly(ʟ-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline α phases with their chain axes preferentially perpendicular to the film plane (c⊥ orientation) have been obtained. This c⊥ orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA α-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films.

Effect of Network-Chain Length on Strain-Induced Crystallization of NR and IR Vulcanizates

2004 ◽  
Vol 77 (4) ◽  
pp. 711-723 ◽  
Author(s):  
Masatoshi Tosaka ◽  
Shinzo Kohjiya ◽  
Syozo Murakami ◽  
Sirilux Poompradub ◽  
Yuko Ikeda ◽  
...  
Keyword(s):  
Small Strain ◽  
Crosslinking Density ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Elongation Ratio ◽  
Network Chain ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Induced Crystallization ◽  
Isoprene Rubber

Abstract Strain-induced crystallization of natural rubber (NR) and synthetic isoprene rubber (IR) with various crosslinking densities was investigated by wide angle X-ray diffraction using a synchrotron radiation and simultaneous tensile measurements. The elongation ratio at the onset of crystallization (αc) was almost independent of crosslinking density. IR samples showed larger αc values than NR because of the lower stereoregularity of IR. These results suggest that the onset of crystallization is determined by increased melting temperature by strain due to an entropic reason. The amount of oriented amorphous component changed approximately linearly with strain, and was a little larger in IR than in NR when compared at the same elongation ratio. At small strain (and stress), crystallinity in IR was lower than in NR. These results indicate that, at small strain region, the more stress is assigned to oriented amorphous in IR than in NR.

scholarly journals CHARACTERISTICS OF STRAIN-INDUCED CRYSTALLIZATION IN NATURAL RUBBER DURING FATIGUE TESTING: IN SITU WIDE-ANGLE X-RAY DIFFRACTION MEASUREMENTS USING SYNCHROTRON RADIATION

2014 ◽  
Vol 87 (1) ◽  
pp. 184-196 ◽  
Author(s):  
S. Beurrot-Borgarino ◽  
B. Huneau ◽  
E. Verron ◽  
D. Thiaudière ◽  
C. Mocuta ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Stretch Ratio ◽  
Fatigue Tests ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Number Of Cycles ◽  
Induced Crystallization

ABSTRACT Strain-induced crystallization of carbon black-filled natural rubber is investigated by wide-angle X-ray diffraction (WAXD) during in situ fatigue tests using synchrotron radiation. Thanks to an original experimental method, we measure the evolution with the number of cycles of: (i) the index of crystallinity, both (ii) size and (iii) orientation of the crystallites, and finally (iv) the lattice parameters. It is shown that when the minimum stretch ratio of the fatigue test is lower than the onset of melting of the crystallites, then the index of crystallinity and the size of the crystallites decrease, whereas they increase when the minimum stretch ratio is higher than the onset of melting. For all the fatigue tests, the misorientation of the crystallites slightly decreases and the lattice parameters remain constant with the number of cycles.

scholarly journals Structure Development during Shear Flow Induced Crystallization of i-PP:  In Situ Wide-Angle X-ray Diffraction Study

2001 ◽  
Vol 34 (17) ◽  
pp. 5902-5909 ◽  
Author(s):  
Rajesh H. Somani ◽  
Benjamin S. Hsiao ◽  
Aurora Nogales ◽  
Hitesh Fruitwala ◽  
Srivatsan Srinivas ◽  
...  
Keyword(s):  
Shear Flow ◽  
Diffraction Study ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Structure Development ◽  
X Ray ◽  
Induced Crystallization ◽  
Flow Induced Crystallization

scholarly journals A mini-goniometer for X-ray diffraction studies down to 4 K on four-circle diffractometers equipped with two-dimensional detectors

2007 ◽  
Vol 40 (3) ◽  
pp. 526-531 ◽  
Author(s):  
Pierre Fertey ◽  
Roger Argoud ◽  
Pierre Bordet ◽  
Jacques Reymann ◽  
Cyril Palin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Mechanical Design ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Original Design ◽  
Data Set ◽  
X Ray ◽  
Density Analysis ◽  
Data Collections

A `universal' low-temperature device for laboratory X-ray diffractometers equipped with two-dimensional detectors has been developed. Single-crystal data collections can be performed down to 4 K. Owing to its original design, the completeness of the data set is not affected by the limited number of accessible orientations of the sample. Classical structure analysis can therefore be performed as well as high-resolution (high-angle) studies for electron-density analysis. Derived from an idea of Argoud & Muller [J. Appl. Cryst.(1989),22, 584–591], the sample is mounted on a holder magnetically coupled to the diffractometer φ axis. The coupling is achieved by mounting a master magnet in place of the usual goniometer head. This magnet drives a slave magnet fixed on the crystal holder: a two-axis mini-goniometer. This low-temperature arrangement is adaptable to any kappa-geometry single-crystal diffractometer equipped with a two-dimensional detector, and can be placed into various types of cryostat. This paper reports the home-made mechanical design and the performance of this device.

Two-dimensional Wide-Angle X-ray Scattering on a Cm-doped borosilicate glass in a beryllium container

2021 ◽  
Vol 28 (1) ◽  
pp. 214-223
Author(s):  
Olivier Bouty ◽  
Laure Ramond ◽  
Kathy Dardenne ◽  
Jörg Rothe
Keyword(s):  
Borosilicate Glass ◽  
Structural Changes ◽  
Glass Network ◽  
High Energy ◽  
Wide Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Diffraction Patterns

The two-dimensional wide-angle X-ray diffraction technique was applied to a Cm-doped borosilicate glass in a beryllium container. The experiment involved a high-energy X-ray beam and an image plate. It is shown that it is possible to extract the structure factor of the radioactive glass successfully from diffraction patterns and compare it with that of the pristine one. Striking differences appear under the first diffraction peak, revealing new sub-structures for the radioactive glass. It is suggested that they could be related to structural changes in the medium-range order, in particular the size distribution of rings or chains under the influence of mixed interactions between the glass network, α-particles and recoil nuclei.

Study on Mechanical Properties of PP Modified by β Nucleating Agent under the Low Temperature

2013 ◽  
Vol 710 ◽  
pp. 97-101
Author(s):  
Jiang Zhu ◽  
Xiang Liu ◽  
Qiang Xu ◽  
Liang Cao
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Room Temperature ◽  
Bending Strength ◽  
Nucleating Agent ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
The Impact

The ethylene-propylene polymer (PP) was modified by using a rare earth β-nucleating agent (WBG-II). The crystallization characteristics of PP induced by WBG-II were investigated through the wide-angle X-ray diffraction (WAXD). The effect of β-nucleating agent on the mechanical property of PP under low temperature was also researched. The results confirmed that β-nucleating agent WBG-II can change the crystal structure of PP and induce the β-form crystals in the PP to develop. Moreover, under the room temperature, with the increment of WBG-II, the tensile strength, bending strength and modulus of the modified PP increase, but the impact strength and elongation at break decrease; and especially at-10 °C, this tendency is more obvious.

Growth and Structure of Tungsten Carbide-Transition Metal Superlattices

1987 ◽  
Vol 103 ◽  
Author(s):  
T. D. Moustakas ◽  
J. Y. Koo ◽  
A. Ozekcin
Keyword(s):  
Low Temperature ◽  
Tungsten Carbide ◽  
Ceramic Materials ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Lattice Imaging ◽  
X Ray ◽  
First Time ◽  
Nanoscale Range ◽  
Low Temperature Process

ABSTRACTSuperlattices between ceramic materials, such as tungsten carbide, and transition metals have been synthesized for the first time. The growth and structure of these superlattices were investigated by low angle X-ray diffraction and TEM lattice imaging and microdiffraction. The data show that the low temperature process of forming these two dimensional composites leads to unique crystal structures and morphology in the nanoscale range.

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