Measurement of orientation crystallization rates of linear polymers by means of dynamic X-ray diffraction technique. II. Frequency dispersion of strain-induced crystallization coefficient of natural rubber vulcanizates in subsonic range

1973 ◽  
Vol 8 (1-2) ◽  
pp. 101-126 ◽  
Author(s):  
Hiroaki Hiratsuka ◽  
Mitsuaki Hashiyama ◽  
Seisuke Tomita ◽  
Hiromichi Kawai
Keyword(s):  
Natural Rubber ◽  
Frequency Dispersion ◽  
Linear Polymers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

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…).

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.

Modified palm stearin compatibilized natural rubber/halloysite nanotubes composites: Reinforcement versus strain-induced crystallization

2020 ◽  
pp. 009524432092857
Author(s):  
Nureeyah Jehsoh ◽  
Indra Surya ◽  
Kannika Sahakaro ◽  
Hanafi Ismail ◽  
Nabil Hayeemasae
Keyword(s):  
Natural Rubber ◽  
Palm Stearin ◽  
Halloysite Nanotubes ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Strain Induced Crystallization ◽  
Diffraction Patterns ◽  
The Relationship ◽  
Induced Crystallization

Natural rubber (NR) is known as hydrophobic material and is incompatible with hydrophilic filler such as halloysite nanotubes (HNTs). To overcome this obstacle, the compatibilizer is a material of choice to incorporate in such compound. In this study, bio-based compatibilizer was used which was prepared by modification of palm stearin. The presence of special functionalities of modified palm stearin (MPS) was confirmed by Fourier transform infrared (FTIR) analysis. It was then varied from 0.5 phr to 2 phr to the NR matrix. Here, the properties were evaluated through the mechanical properties with special attention to the relationship between their reinforcement and crystallization behavior after stretching. It was found that the addition of MPS significantly enhanced the modulus, tensile strength, and tear strength of the composites. This clearly corresponded to interaction between NR and HNT promoted by MPS. The FTIR spectrum, X-ray diffraction patterns, and scanning electron microscopy images were also utilized to verify the behavior of MPS in the NR/HNT composites. As for the crystallization of the composites, the results obtained from stress–strain curves are in very good agreement to the outputs observed by the synchrotron wide-angle X-ray scattering. This corresponding interaction of MPS has greatly influenced on assisting the strain-induced crystallization of composites.

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