Crystal and Crystallites Structure of Natural Rubber and Synthetic cis-1,4-Polyisoprene by a New Two Dimensional Wide Angle X-ray Diffraction Simulation Method. I. Strain-Induced Crystallization

2013 ◽  
Vol 46 (11) ◽  
pp. 4520-4528 ◽  
Author(s):  
Justin Che ◽  
Christian Burger ◽  
Shigeyuki Toki ◽  
Lixia Rong ◽  
Benjamin S. Hsiao ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Simulation Method ◽  
Wide Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

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.

scholarly journals The Orientation of Strain-Induced Crystallites in Uniaxially-Strained, Thin and Wide Bands Made from Natural Rubber

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 294 ◽  
Author(s):  
Konrad Schneider ◽  
Matthias Schwartzkopf
Keyword(s):  
Natural Rubber ◽  
Pure Shear ◽  
Orientation Distribution ◽  
Thin Strip ◽  
X Ray Diffraction ◽  
Reinforcing Effect ◽  
X Ray ◽  
Crack Tips ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Vulcanized natural rubber (unfilled and filled with 20 phr carbon black) is strained. We suppress the macroscopic formation of fiber symmetry by choosing strip-shaped samples ("pure-shear geometry") and investigate the orientation of the resulting crystallites by two-dimensional wide-angle X-ray diffraction (WAXD), additionally rotating the sample tape about the straining direction. Indications of a directed reinforcing effect of the strain-induced crystallization (SIC) in the thin strip are found. In the filled material fewer crystallites are oriented and the orientation distribution of the oriented crystallites is less perfect. The results confirm, that it is important for the evaluation of crystallinity under deformation to check, whether fiber symmetry can be assumed. This has consequences in particular on the quantitative interpretation of space-resolved scanning experiments in the vicinity of crack tips. Furthermore it raises the question, whether there is an asymmetric reinforcing effect of the SIC in the vicinity of crack tips inside natural rubber.

scholarly journals STRAIN-INDUCED CRYSTALLIZATION OF NATURAL RUBBER: A REVIEW OF X-RAY DIFFRACTION INVESTIGATIONS

2011 ◽  
Vol 84 (3) ◽  
pp. 425-452 ◽  
Author(s):  
Bertrand Huneau
Keyword(s):  
Natural Rubber ◽  
Mechanical Response ◽  
Strain Curve ◽  
Fatigue Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Temperature Strain ◽  
Kinetics Of ◽  
Induced Crystallization

Abstract Strain-induced crystallization of natural rubber was discovered in 1925 by the means of x-ray diffraction and has been widely investigated by this technique until today. The studies devoted to the structure of the crystalline phase of natural rubber are first reviewed. This structure is strongly anisotropic and can be related to the exceptionally good strength and fatigue properties of this material. The relationships between strain-induced crystallization of natural rubber and its mechanical response, during static or tension-retraction tests, are also reviewed and discussed; in particular, the hysteresis of the stress-strain curve is mainly explained by strain-induced crystallization. The kinetics of crystallization under both static and cyclic deformation is also discussed, as well as the influence of different factors, depending either on material composition (crosslink density, carbon black fillers) or on external parameters (temperature, strain rate…).

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.

INFLUENCE OF STRAIN-INDUCED CRYSTALLIZATION ON STRESS SOFTENING OF SULFUR CROSS-LINKED UNFILLED GUAYULE AND DANDELION NATURAL RUBBERS

2019 ◽  
Vol 92 (2) ◽  
pp. 388-398
Author(s):  
P. Junkong ◽  
Y. Matsushima ◽  
T. Phakkeeree ◽  
K. Cornish ◽  
Y. Ikeda
Keyword(s):  
Natural Rubber ◽  
Cyclic Deformation ◽  
X Ray Diffraction ◽  
Key Factors ◽  
Average Volume ◽  
X Ray ◽  
Stress Softening ◽  
Strain Induced Crystallization ◽  
Stretching Ratio ◽  
Induced Crystallization

ABSTRACT The stress softening behaviors of sulfur cross-linked unfilled guayule natural rubber (S-GR) and sulfur cross-linked unfilled dandelion natural rubber (S-DR) under cyclic deformation were characterized by simultaneous wide angle X-ray diffraction and tensile measurements under cyclic deformation. The behaviors were found to be affected by their strain-induced crystallization (SIC) phenomena and aggregated nonrubber components. The stress softening degree at stretching ratio = 8.0 of S-DR was almost two times larger than that of S-GR. Additionally, the hysteresis loss and residual strain of S-DR were much higher than those of S-GR in the same cycle. The key factors that caused the increase in their degree of stress softening were the increase in average volume and the decrease in average number of strain-induced crystallites upon cyclic deformation, not the insignificant decrease in crystallinity. The breakage of the aggregated nonrubber components is a main origin of stress softening behaviors for S-GR and S-DR because their SIC behaviors also were significantly influenced by the aggregates of nonrubber components in the rubber matrixes. Both the effects of nonrubber components and SIC on stress softening were more dominant in S-DR than in S-GR, probably owing to the larger amount of aggregated nonrubber components in the former than in the latter. The results will be useful in effectively using guayule and dandelion natural rubbers as alternatives to Hevea natural rubber in the rubber industry.

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