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Kankroli, India

Ghosh P.,Indian Institute of Technology Madras | Ghosh P.,Tyre Research Institute | Stocek R.,PRL Polymer Research Laboratory | Gehde M.,TU Chemnitz | And 2 more authors.
International Journal of Fracture

Tyre tread directly comes in contact with various road surfaces and is prone to damage due to cuts from sharp objects during service. As tyres undergo millions of fatigue cycles, these cuts propagate continuously and lead to catastrophic failure. Therefore fatigue crack growth (FCG) characteristics should be an essential criterion for tread compound selection. The present study investigates FCG behavior of blends comprising of Natural Rubber (NR) and Polybutadiene Rubber (BR) over a wide range of tearing energy. Pure shear specimens with a notch on both edges were tested in a Tear Analyser. Rapid increase in FCG rate after a certain strain level was observed. This transition point appeared in a strain range of 20-35 %, depending on the blend composition. The higher BR containing compounds exhibited better FCG characteristics below the transition point but reversal of ranking was seen above this point. The influence of temperature, R ratio, waveforms and cure system on FCG characteristics was also investigated in NR and 60-40 NR/BR blend compounds. Higher FCG rate was achieved under pulse loading compared to the sine waveform. The relaxation time between pulse cycles played an important role. With an increase in relaxation time, FCG rate decreases significantly. The higher sensitivity towards R ratio was observed in NR compound. The 60-40 NR/BR blend showed higher FCG rate with increase in temperature compared to the NR compound. The NR compound with high Sulfur/Accelerator (S/Ac) ratio showed better FCG characteristics whereas for 60-40 NR/BR blend with low S/Ac ratio achieved superior FCG characteristics. © 2014 Springer Science+Business Media Dordrecht. Source

Chakraborty S.,Tyre Research Institute | Kar S.,Tyre Research Institute | Ameta R.,Tyre Research Institute | Dasgupta S.,Tyre Research Institute | Mukhopadhyay R.,Tyre Research Institute
Rubber World

The quantitative application of Modern Fourier Transform Infrared (FTIR) in rubber is described. When infrared light is passed through a sample of an organic compound, some of the frequencies are absorbed, while other frequencies are transmitted through the sample without being absorbed. FTIR instruments are normally based on Michelson's interferometer, in which the radiation from an infrared source is split into two beams by a half silvered 45° mirror in such a way that the resulting beams are at right angles to each other. EVA is extensively used in the rubber industry as a wrapping poly for different rubbers like SBR and IIR. EVA is also used in the form of a bag to prepare a weighing bag for rubber chemicals. The correlation coefficient was 0.99. The ACN content of the unknown NBR rubber was calculated from the correlation equation. The acrylonitrile content calculated from the equation showed good agreement with the actual value. Source

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