Molecular Mobility of Unfilled and Carbon-Black-Filled Isoprene Rubber: Proton NMR Transverse Relaxation and Diffusion

2007 ◽  
Vol 80 (5) ◽  
pp. 854-872 ◽  
Author(s):  
Ximei Sun ◽  
Avraam I. Isayev ◽  
Tirtha R. Joshi ◽  
Ernst von Meerwall
Keyword(s):  
Molecular Mobility ◽  
Solid State Nmr ◽  
T2 Relaxation ◽  
Transverse Relaxation ◽  
Network Chain ◽  
Short T2 ◽  
Gradient Diffusion ◽  
And Diffusion ◽  
Relaxation Decay ◽  
Isoprene Rubber

Abstract In an effort to understand the effect of ultrasound on the devulcanization of gum and filled isoprene rubber vulcanizates, solid state NMR 1H transverse relaxation (T2) was employed to analyze rubber molecular mobility. The T2 relaxation decay of the unfilled and the black filled IR was successfully described by a two-component model. The short T2 component arose from the chemically crosslinked (gel) and physically entangled (heavy sol) network. The long T2 decay came from the unentangled sol and dangling network chain ends. Vulcanization decreased the molecular mobility; however, ultrasound devulcanization partially reversed this effect. Addition of processing oil in the filled IR significantly altered the dependence of T2 on the sol fraction. T2 and pulsed-gradient diffusion experiments were carried out on IR melt specimens after sonication with or without subsequent vulcanization. The lowered and broadened M-distribution produced results quantitatively related to earlier work in natural rubber.

T2 Relaxation and Diffusion of Collagen Gel Oriented.

2005 ◽  
Vol 29 (3) ◽  
pp. 347-350
Author(s):  
M. Takeuchi ◽  
M. Sekino ◽  
N. Iriguchi ◽  
S. Ueno
Keyword(s):  
Collagen Gel ◽  
T2 Relaxation ◽  
And Diffusion

Biexponential parameterization of diffusion and T2 relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments

2005 ◽  
Vol 54 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Zaid Ababneh ◽  
Helene Beloeil ◽  
Charles B. Berde ◽  
Giulio Gambarota ◽  
Stephan E. Maier ◽  
...  
Keyword(s):  
Decay Curve ◽  
T2 Relaxation ◽  
Rat Muscle ◽  
Water Compartments ◽  
Edema Model ◽  
Muscle Edema ◽  
Relaxation Decay

A solid-state NMR study of the structure and molecular mobility of α-keratin

2003 ◽  
Vol 5 (13) ◽  
pp. 2894-2899 ◽  
Author(s):  
Melinda J. Duer ◽  
Nicky McDougal ◽  
Rachel C. Murray
Keyword(s):  
Solid State ◽  
Molecular Mobility ◽  
Solid State Nmr ◽  
Nmr Study

A method for imaging nuclei with short T2 relaxation and its application to boron-11 NMR imaging of a BNCT agent in an intact rat

1990 ◽  
Vol 88 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Peter Bendel ◽  
Mark Davis ◽  
Elisha Berman ◽  
George W Kabalka
Keyword(s):  
Nmr Imaging ◽  
T2 Relaxation ◽  
Short T2

Molecular Mobility in Swollen Cross-linked Rubbers. Viscoelasticity and Diffusion Measurements

1971 ◽  
Vol 2 (2) ◽  
pp. 274-282 ◽  
Author(s):  
Chiu-Ping Wong ◽  
John L. Schrag ◽  
John D. Ferry
Keyword(s):  
Molecular Mobility ◽  
And Diffusion

Molecular Mobility in Ultrasonically Devulcanized Unfilled Butadiene Rubber

2004 ◽  
Vol 77 (4) ◽  
pp. 745-758 ◽  
Author(s):  
Jeong Seok Oh ◽  
A. I. Isayev ◽  
E. von Meerwall
Keyword(s):  
Silicone Rubber ◽  
Mean Diffusivity ◽  
Nmr Relaxation ◽  
Butadiene Rubber ◽  
Nmr Studies ◽  
Transverse Relaxation ◽  
Gradient Diffusion ◽  
Before And After ◽  
Rubber Recycling ◽  
Crosslinked Networks

Abstract We have used NMR relaxation and pulsed-gradient diffusion measurements at 70 °C in unfilled butadiene rubber (BR) before and after crosslinking, and after subsequent devulcanization by intense ultrasound. In an effort to support this method of rubber recycling, characterization has been performed at the molecular level. The transverse relaxation (T2) decay was successfully described using a three-component model. The components are attributed to entangled and crosslinked networks; light sol and dangling network fragments; and partially unreactive oligomers. All component molecular mobilities and the relative contributions of the components to the echo were investigated. Devulcanization decreases the diffusivity of the oligomer remnants and increases mean diffusivity of the light sol. The additional amount of extractable sol produced by devulcanization of BR is more than that of silicone rubber, indicating that the ultrasonic devulcanization of BR is more efficient than that of silicone rubber. The present results are compared with our previous NMR studies of devulcanized rubbers.

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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