Synchrotron X-Ray Studies of Vulcanized Rubbers and Thermoplastic Elastomers

2006 ◽  
Vol 79 (3) ◽  
pp. 460-488 ◽  
Author(s):  
Shigeyuki Toki ◽  
Benjamin S. Hsiao ◽  
Shinzo Kohjiya ◽  
Masatoshi Tosaka ◽  
Andy H. Tsou ◽  
...  
Keyword(s):  
Hybrid Structure ◽  
Thermoplastic Elastomers ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Strain Induced Crystallization ◽  
Different Strains ◽  
Induced Crystallization

Abstract Synchrotron X-ray diffraction technique has revealed strain-induced crystallization and molecular orientation in vulcanized rubbers and thermoplastic elastomers (TPE) during deformation in real time. The stress-strain curves and wide angle X-ray diffraction (WAXD) patterns in vulcanized rubbers and TPE were measured simultaneously. In-situ WAXD patterns were taken not only at different strains during uniaxial deformation but also at different temperatures at a constant strain. Results lead to several new insights. (i) Strain-induced crystallization is a common phenomenon in vulcanized rubbers, except SBR (styrene-butadiene rubber), and in TPE (with crystalline hard segments). (ii) Strain-induced crystallization decreases the stress and increases the elongation in the strained rubber. (iii) The hybrid structure of chemical networks and strain-induced crystallites is responsible to the tensile strength and elongation at break for both systems. (iiii) Some original crystal fraction (hard segment domain) in TPE is destroyed. During deformation, strain-induced crystallization increases with strain. Upon retraction even to stress zero, the majority of oriented strain-induced crystallites remains in tack with preferred orientation.

Strain-Induced Molecular Orientation and Crystallization in Natural and Synthetic Rubbers under Uniaxial Deformation by In-situ Synchrotron X-ray Study

2004 ◽  
Vol 77 (2) ◽  
pp. 317-335 ◽  
Author(s):  
Shigeyuki Toki ◽  
Igors Sics ◽  
Shaofeng Ran ◽  
Lizhi Liu ◽  
Benjamin S. Hsiao ◽  
...  
Keyword(s):  
Molecular Orientation ◽  
Amorphous State ◽  
Butadiene Rubber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
The Relationship ◽  
Induced Crystallization ◽  
Natural And Synthetic

Abstract In-situ synchrotron wide-angle X-ray diffraction (WAXD) studies and simultaneous measurements of stress and strain during uniaxial stretching of various vulcanized rubbers were carried out (at room temperature and 0°C) to reveal the strain-induced molecular orientation and crystallization relationships. Rubbers evaluated included natural rubber (NR), synthetic poly-isoprene rubber (IR), poly-cis-1,4-butadiene rubber (BR) and butyl rubber (IIR). Some universal features were observed in these systems: (i) At high strains (> 5.0), the majority of the chains (up to 50 ≈ 75%) in natural and synthetic rubbers remained in the un-oriented amorphous state with only a small amount of crystalline fraction formed (10–20%). The rest of the chains were in the oriented amorphous state. (ii) During deformation, the oriented amorphous chains acted as precursors to strain-induced crystallization. A network of micro-fibrillar crystallites is formed within the closely populated vulcanization points, leading to the enhancement of mechanical properties at high strains. Different rubbers exhibited different behaviors during strain-induced crystallization. For example, poly-isoprenes (NR and IR vulcanized with sulfur and peroxide) showed strain-induced crystallization at a low strain of 2.5, resulting in larger crystalline but smaller oriented amorphous fractions. In contrast, BR and IIR crystallized at a higher strain of 4.0 lead to higher molecular orientation, higher oriented amorphous, but smaller crystalline fractions. The relationship between the molecular orientation and crystallization in strained rubber depends on the intrinsic crystallizability of the chains and the topology of the crosslinked network.

scholarly journals Influence of Temperature on Mechanical Properties of P(BAMO-r-THF) Elastomer

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2507
Author(s):  
Jinxian Zhai ◽  
Hanpeng Zhao ◽  
Xiaoyan Guo ◽  
Xiaodong Li ◽  
Tinglu Song
Keyword(s):  
Mechanical Properties ◽  
X Ray Diffraction ◽  
Polymeric Chains ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
Strain Induced Crystallization ◽  
Thermal Histories ◽  
Static Conditions ◽  
The Relationship ◽  
Induced Crystallization

The relationship between temperature and the mechanical properties of an end cross-linked equal molar random copolyether elastomer of 3,3-bis(azidomethyl)oxetane and tetrahydrofuran (P(BAMO-r-THF)) was investigated. During this investigation, the performances of two P(BAMO-r-THF) elastomers with different thermal histories were compared at different temperatures. The elastomer as prepared at 20 °C (denoted as S0) exhibited semi-crystallization morphology. Wide angle X-ray diffraction analysis indicated that the crystal grains within elastomer S0 result from the crystallization of BAMO micro-blocks embedded in P(BAMO-r-THF) polymeric chains, and the crystallinity is temperature irreversible under static conditions. After undergoing a heating-cooling cycle, this elastomer became an amorphous elastomer (denoted as S1). Regarding mechanical properties, at 20 °C, break strains and stresses of 315 ± 22% and 0.46 ± 0.01 MPa were obtained for elastomer S0; corresponding values of 294 ± 6% and 0.32 ± 0.02 MPa were obtained for elastomer S1. At −40 °C, these strains and stresses simultaneously increased to 1085 ± 21% and 8.90 ± 0.72 MPa (S0) and 1181 ± 25% and 10.23 ± 0.44 MPa (S1), respectively, owing to the strain-induced crystallization of BAMO micro-blocks within the P(BAMO-r-THF) polymeric chains.

In situ characterization of strain-induced crystallization of natural rubber by synchrotron radiation wide-angle X-ray diffraction: construction of a crystal network at low temperatures

Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 734-743 ◽  
Author(s):  
Pinzhang Chen ◽  
Jingyun Zhao ◽  
Yuanfei Lin ◽  
Jiarui Chang ◽  
Lingpu Meng ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
In Situ Characterization ◽  
X Ray ◽  
Crystal Network ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

The structural evolution of NR during stretching at −40 °C and in the strain–temperature space.

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.

Probing the Nature of Strain-Induced Crystallization in Polyisoprene Rubber by Combined Thermomechanical and In Situ X-ray Diffraction Techniques

2005 ◽  
Vol 38 (16) ◽  
pp. 7064-7073 ◽  
Author(s):  
Shigeyuki Toki ◽  
Igors Sics ◽  
Benjamin S. Hsiao ◽  
Masatoshi Tosaka ◽  
Sirilux Poompradub ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

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…).

Polysilicon Films Formed on Metal Sheets by Aluminium Induced Crystallization of Amorphous Silicon: Barrier Effect

2009 ◽  
Vol 1153 ◽  
Author(s):  
Prathap Pathi ◽  
Ozge Tüzün ◽  
Abdelilah Slaoui
Keyword(s):  
Amorphous Silicon ◽  
Electron Beam Evaporation ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coated Metal ◽  
Metal Sheets ◽  
Different Temperatures ◽  
Si Films ◽  
Induced Crystallization

AbstractPolycrystalline silicon (pc-Si) thin films have been synthesized by aluminium induced crystallization (AIC) of amorphous silicon (a-Si) at low temperatures (≤500°C) on flexible metallic substrates for the first time. Different diffusion barrier layers were used to prepare stress free pc-Si films as well as to evaluate the effective barrier against substrate impurity diffusion. The layers of aluminum (Al) and then amorphous silicon with the thickness of 0.27 μm and 0.37 μm were deposited on barrier coated metal sheets by means of an electron beam evaporation and PECVD, respectively. The bi-layers were annealed in a tube furnace at different temperatures (400-500°C) under nitrogen flow for different time periods (1-10hours). The degree of crystallinity of the as-grown layers was monitored by micro-Raman and reflectance spectroscopies. Structure, surface morphology and impurity analysis were carried out by X-ray diffraction, scanning electron microscopy (SEM) and EDAX, respectively. The X-ray diffraction measurements were used to determine the orientation of grains. The results show that the AIC films on metal sheets are polycrystalline and the grains oriented in (100) direction preferentially. However, the properties of AIC films are highly sensitive to the surface roughness.

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.

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