scholarly journals Analysis of Crosslinked Natural Rubber by Spin-spin Relaxation Spectra

2012 ◽  
Vol 48 (4) ◽  
pp. 121-126 ◽  
Author(s):  
Hitoshi IWABUKI ◽  
Sigeki HIKASA
Keyword(s):  
Natural Rubber ◽  
Spin Relaxation ◽  
Relaxation Spectra

SPIN RELAXATION SPECTRA OF Γ8 QUARTET

1976 ◽  
Vol 37 (C6) ◽  
pp. C6-85-C6-88
Author(s):  
G. K. SHENOY ◽  
B. D. DUNLAP ◽  
S. DATTAGUPTA ◽  
L. ASCH
Keyword(s):  
Spin Relaxation ◽  
Relaxation Spectra

Investigation of Un-Vulcanized Natural Rubber by Means of Temperature Scanning Stress Relaxation Measurements

2013 ◽  
Vol 718-720 ◽  
pp. 117-123 ◽  
Author(s):  
Miao Wu ◽  
Michael Heinz ◽  
Norbert Vennemann
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Natural Rubber ◽  
Branch Points ◽  
Relaxation Spectra ◽  
Green Strength ◽  
Testing Method ◽  
Relaxation Measurements ◽  
Different Types ◽  
Temperature Scanning

Two different types of un-vulcanized natural rubber, air dried sheets (ADS) and SVR-3L block rubber, were investigated by a new testing method and the results are compared with other mechanical properties. It was found that green strength is strongly reduced if the sample is ther­mal­ly treated before testing. Presumably, the decrease of strength is caused by a decrease of branch points, mainly composed of phospholipids, which are linked to the a - terminal groups of the rubber molecules. The existence of two different types of branch points is indicated by relaxation spectra, obtained from temperature scanning stress relaxation (TSSR) measurements.

scholarly journals Gaussian Expansion of Spin-spin Relaxation for Mastication of Natural Rubber

2010 ◽  
Vol 46 (9) ◽  
pp. 326-331
Author(s):  
Hitoshi IWABUK ◽  
Koji MURAKAMI ◽  
Sigeki HIKASA ◽  
Katsushi NISH
Keyword(s):  
Natural Rubber ◽  
Spin Relaxation

Determination of Crosslink Density and Network Structure of NR Vulcanizates by Means of TSSR

2013 ◽  
Vol 844 ◽  
pp. 482-485 ◽  
Author(s):  
Norbert Vennemann ◽  
Christina Schwarze ◽  
Claudia Kummerlöwe
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Network Structure ◽  
Crosslink Density ◽  
Relaxation Spectrum ◽  
Strong Impact ◽  
Relaxation Spectra ◽  
Peak Separation ◽  
Temperature Scanning

Unfilled vulcanizates based on natural rubber (NR) were investigated by temperature scanning stress relaxation (TSSR) measurements. Different sulfur based cure systems, i.e. conventional (CV), semi-efficient (SEV) and efficient (EV) vulcanization system, were used to prepare the vulcanizates. It was found that sulfur/accelerator - ratio has a strong impact on the shape of the relaxation spectrum, deduced from TSSR measurements. By deconvolution of the relaxation spectra, peak separation was performed and 3 different peaks were found in case of CV - cured samples. In contrast, only a single peak was found, in case of the EV-cured sample. After thiolamine treatment the shape of the relaxation spectra altered significantly in case of the CV-cured sample whereas the spectra of the SEV-and EV-cured sample exhibited only slight differences. Additionally, the crosslink density of the samples decreased after thiolamine treatment. This is due to selective cleavage of polysulfidic crosslinks. It has been concluded, that the significant peak in the relaxation spectrum at about 120 °C can be attributed to the cleavage of polysulfidic crosslinks. Furthermore, a linear relationship between the percentage of polysulfidic crosslinks and the sulfur/accelerator - ratio is assumed.

Polystyrene-Natural-Rubber Mixtures: Preparation and Properties

1993 ◽  
Vol 66 (1) ◽  
pp. 14-18
Author(s):  
S. Valić ◽  
M. Topić ◽  
M. Andreis ◽  
F. Ranogajec ◽  
Z. Veksli ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Spin Relaxation ◽  
Thermoplastic Elastomers ◽  
Depolarization Current ◽  
Thermally Stimulated Depolarization Current ◽  
Polystyrene Surface ◽  
Mechanical Measurements ◽  
Relaxation Measurements ◽  
Thermally Stimulated Depolarization

Abstract Thermoplastic elastomers were prepared from mixtures of polystyrene and natural-rubber latexes. The mechanical measurements, thermally stimulated depolarization current measurements, and NMR spin-spin relaxation measurements have shown that the properties of prepared thermoplastic elastomers depend on the composition and the interface created by changing the size of the accessible polystyrene surface.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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