Faculty Publications

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Photomechanical actuation of polydimethylsiloxane/carbon black nanocomposite
(Institution of Engineering and Technology jbristow@theiet.org, 2020) Hiremath, S.; Kulkarni, S.M.
Materials such as carbon black (CB), carbon nanotube, graphene, etc. have been found to deform on exposure to the light source. Introducing these materials into polymers could convert them to photo-responsive composites. This is demonstrated by the experiment in which polydimethylsiloxane (PDMS) polymer containing CB nanofiller composites is prepared, and its photomechanical actuation from exposure to IR light source is recorded using a laser displacement sensor. The particle size analysis reveals the size of the CB, which is verified by the dynamic light scattering method. The UV-vis-IR spectrophotometer study shows that an increase in the light absorbance capacity of nanocomposites compared to the plain polymer. The PDMS/CB nanocomposite beam exhibited a significant deformation compared to plain PDMS. Deformation of the order of 10-11 mm is observed for a given IR source. The deformation found to have good repeatability but with some thermal hysteresis in cyclic actuation and de-actuation. © 2020 Institution of Engineering and Technology. All rights reserved.
Numerical analysis of polymer composites for actuation
(International Information and Engineering Technology Association, 2020) Hiremath, S.; Sangappa, V.; Rajole, S.; Kulkarni, S.M.
The design of a polymer composite actuator is essential for micro and nano applications. Thus, the composite material may deform or deflects as specific stimuli are applied, such as heat, electrical, light source, etc. The deformation of the composite material is caused by the type of stimulus applied. Hence, while it is heated, the expansion takes place quickly, and the heating is shut down, the material shrinks very slowly. In the present investigation, this phenomenon is mainly studied in the actuation of composite beams. Numerical analysis of carbon black filled polymer composite beam expansion, and contraction is being analyzed in this research. The structure of the beam has been created, and the composite properties are incorporated into the beam, and the uniform heat source is applied on to the surface of the beam. The heating and cooling of the composite material predict the increase and decrease in the temperature of the beam. The numerical analysis of the temperature-dependent expansion and contraction of the composite beam has been carried out successfully. An increase in temperature is observed to signify the slight expansion in the composite beam, whereas the contraction of the composite beam takes a longer time to reach room temperature. Also, the increase in the content of the filler leads to a decrease in the expansion of the composite beam. The numerical simulation of the polymer composite thus provides a solid platform for the experimental study of thermal actuators. © 2020 Lavoisier. All rights reserved.
Progression and characterization of polydimethylsiloxane-carbon black nanocomposites for photothermal actuator applications
(Elsevier B.V., 2021) Hiremath, S.; H, S.M.; Kulkarni, S.M.
The new development of polymer-based actuators triggers the progress of nanocomposites. Polymer materials are currently used in sensors, microfluidic devices, electrical and thermal actuators, and energy harvesting applications due to ease of availability, excellent tolerable properties, and customizable properties. The polymer-based nanocomposite can be driven by various stimuli, which is the actuator's emerging field. Thus, photothermal actuation is a thurst area of research transforming light energy into mechanical energy through the polymer material. The photo-responsive material can be prepared and tested for photo-actuation by incorporating the nanoparticles into the polymer. The present work focuses on developing polydimethylsiloxane (PDMS) and carbon black (CB) nanocomposite. The objective here is to investigate the photothermal actuator's performance by illuminating the infrared (IR) light source and studying its most influential characteristics, such as absorbance, thermal conductivity, and the thermal expansion coefficient. The PDMS / CB nanocomposite absorbs the IR light and then increases temperature, which is finally transformed into a beam deflection. Responses are measured as a result of time deflection using the Laser displacement sensor. It is noted that the deflection of the nanocomposite beam is linearly increased during illumination with light while it is exponentially decreasing when the light is turned off. The proposed polymer nanocomposite is approximately deflected by 9 mm in the duration of 16 s duration. Furthermore, the experimental deflection of the photothermal actuator is very close to theoretical results. The nanocomposite PDMS / CB reveals that there is an increase in absorbance by increasing the filler content. The nanocomposite conductivity is 35.2 % higher than the base material. As well, the thermal expansion coefficient decreases with an increase in carbon black content. The photothermal actuator's development is an ongoing process in which the material parameter, actuator geometry, and many more are modified. As a result, the photothermal bending performed can provide a means for various light-driven applications. © 2020 Elsevier B.V.

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