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Vadodara, India

CEAT Ltd | Date: 2007-02-27


Kumar S.,Indian Institute of Technology Kharagpur | Chattopadhyay S.,Indian Institute of Technology Kharagpur | Padmanabhan R.,Indian Institute of Technology Kharagpur | Sreejesh A.,CEAT Ltd | And 3 more authors.
Materials Research Express | Year: 2015

In the present work, we have attempted to study the effects of graphene nanoplatelets (GNPs) on various properties with a focus on the air and water vapor barrier properties of novel rubber nanocomposites. Bromobutyl rubber (BIIR) was blended with a highly impermeable polyepichlorohydrin rubber (CO) and thereafter hybrid filler-based nanocomposites were prepared with a commercially viable technique. Shear thinning and lower die swell (up to 30% reduction) invokes better processability of the nanocomposites. The tensile modulus increases by up to 20% in the nanocomposites. It has been found that the addition of GNPs markedly increases the thermal stability, but considerably decreases air permeability (up to 20%) and water vapor transmission rate (up to 20%) of the nanocomposites. This has been achieved because of the high degree of reinforcement as well as due to the increasingly tortuous paths created by the novel nanostructure of the fillers. Maxwell-Wagner polarization at lower frequency also provides an insight into such nanostructures leading to improved electrical conductivity. This unique scheme has been exclusively developed to understand the structural effect of GNPs on the barrier properties. It infers that air permeability is tortuosity dependent, whereasWVTRis polarity dependent on the rubber nanocomposites. Dispersion of GNPs is pivotal in imparting the overall performance of the nanocomposites, suggesting that a lower dosage of GNPs (up to 3 phr) is better. © 2015 IOP Publishing Ltd.

Sankaran K.,Indian Institute of Technology Kharagpur | Manoharan P.,Indian Institute of Technology Kharagpur | Chattopadhyay S.,Indian Institute of Technology Kharagpur | Nair S.,CEAT Ltd | And 3 more authors.
RSC Advances | Year: 2016

The present work provides extensive insight into the effect of hybridization of organoclay with carbon black and their structure-property relationships on nanocomposites based on bromobutyl rubber (BIIR)/epoxidized natural rubber (ENR) blends. Morphology studies reveal well-dispersed nanoclay with the formation of hybrid nanostructures. Synergistic interaction between carbon black and nanoclay increases the tensile modulus and tear strength of the nanocomposites. The effect of layered clay platelets on the transport properties invokes a drastic reduction in the air permeability of up to 25% and in the water vapor transmission rate of up to 35%, and an increment in the electrical and thermal conductivity of the rubber nanocomposites. The peel strength with the rubberized fabric is found to be good for the nanocomposite with a lower elastic modulus. These unique attributes were found to stem from the formation of well dispersed hybrid nanostructures. Rubber formulations with such suitably tailored nanostructures will find applications in next generation rubber-based industrial products. © The Royal Society of Chemistry 2016.

Kumar S.,Indian Institute of Technology Kharagpur | Chattopadhyay S.,Indian Institute of Technology Kharagpur | Sreejesh A.,CEAT Ltd | Nair S.,CEAT Ltd | And 2 more authors.
Materials Research Express | Year: 2015

This work focuses on analyzing the barrier properties of novel Bromobutyl (BIIR)- Polyepichlorohydrin (CO) rubber nanocomposites and developing a unique model to ease the underst and ing of the water vapor transmission rate (WVTR) properties. Air permeability,WVTR and morphology of BIIR-CO nanocomposites were investigated and compared with the st and ard BIIR vulcanizate. From the morphological studies using AFM imaging technique and HR-TEM measurements, the developed BIIR-CO nanocomposites were considered to have a mostly intercalated structure. However, the dispersion of the nanoclay in the composites was very good. Air permeability of BIIR-CO nanocomposites decreased dramatically by 64% as compared to that of the st and ard BIIR vulcanizate. Considerable reduction in WVTR up to 25% was also achieved for BIIR-CO nanocomposites. Attempts were made to fit the experimental data of the relative gas permeability of nanocomposites with various models predicted earlier. It was observed that the nanoclay orientation ranged from perfect to r and om, which was decisive in improving the gas barrier properties. A basic model has been developed to predict the water vapor ingress by considering the polarity factor along with tortuosity factor which has been presented schematically. It reiterates the dependency of water vapor ingress on the polarity of the BIIR-CO rubber nanocomposites. © 2015 IOP Publishing Ltd.

Unnikrishnan G.,Indian Institute of Technology Kanpur | Tiwari N.,Indian Institute of Technology Kanpur | Saraswat A.,CEAT Ltd | Goyal S.,CEAT Ltd | Kumar U.,CEAT Ltd
INTER-NOISE 2015 - 44th International Congress and Exposition on Noise Control Engineering | Year: 2015

In this work we propose a computational model to predict the noise produced in rolling tires by the phenomena of air pumping. The model uses pitch sequence, pitch length, pitch width, pitch angle, speed of vehicle, length of contact patch, and compression of tread as input parameters and then predicts the noise generated by treads in time and frequency domains. The model uses all these parameters to compute volume velocity associated with the phenomena of air-pumping. This volume velocity function is subsequently numerically processed to compute sound pressure level at a given distance in free-field conditions in both dB and dB(A) units. The predicted pressure results are compared with limited experimental data. Using such a prediction model, sensitivity studies are conducted to explore the influence of change in various tread parameters on the tread noise generated by a moving tire. © 2015 by ASME.

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