Use of hybrid fillers as a reinforcing agent for polymers is found to be critical step toward developing a high-performance composite material. However, limited know-how on the nature of interaction of the hybrid fillers with the polymer chains resulted in a major impediment toward large-scale transmissibility of such a technology. Herein, we report about a strategy, wherein the polymer composite (free of curatives), comprising of hybrid filler and its gel was leveraged to effectively understand the physics involved toward reinforcement. Styrene-butadiene random copolymer as the matrix, and combination of expanded graphite and carbon black (N220) as the model hybrid filler were selected. The hybrid filler containing composite (SG22) demonstrated significant improvement in terms of the physico-mechanical properties such as tensile strength, modulus and so forth compared to the neat carbon black-filled system (S22). Stress-relaxation studies indicated that SG22 registered minimal decay in the force with time compared to S22. SG22 demonstrated a gel fraction of 68 ± 1% while 56 ± 1% was noted for S22. Further, rheometric studies like strain sweep, frequency sweep, complex viscosity of the gel fragments indicated the formation of fractal network of the hybrid fillers inside the polymer matrix. Small angle X-ray studies corroborated the crucial role played by the expanded graphite sheets in determining the microstructure of the composite owing to their lubrication effect and segregation of carbon black agglomerates by cutting through their sharp edges resulting in a well-distributed filler network.
The petroleum heavy oils or residual oils are known to contain large amounts of sulfur, causing significant environmental concerns during the partial or complete combustion of these oils. The removal of sulfur species from such oil fractions is extremely difficult due to the recalcitrant nature of the sulfur species. The present work describes a novel process for sulfur removal from high boiling, high viscosity petroleum fractions, wherein a sulfur removal efficiency as high as 95% is observed. The process also sees a reduction in the asphaltene content of the treated oils by more than 50%. Further, the viscosity of the desulfurized oil was found to be significantly reduced by more than 90% as compared to that of the untreated or raw oil fraction. It is envisaged that utilization of this process for desulfurization of residual oils will result in much reduced SOx emissions, with accompanying environmental benefits.
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