Master of Science, University of Akron, 2019, Chemical Engineering

The next generation electronic devices are expected to be small in size and of magnified capacity. Denser packaging of the active components is important to miniaturize the electronic devices. Denser packaging is feasible only when heat generated by heat sources is quickly and effectively carried away to the heat sink. Next generation electronic devices with high performance microprocessors and integrated circuits along with diminished volume have led to major heat dissipation issue. Heat dissipation helps to control the temperature of the electronic devices at a desired level. Heat is dissipated to the heat sink from heat generator by the process of thermal conduction. Due to irregularities on the surfaces of the heat generator and heat sink, air is entrapped, and the air gap is formed in the path of thermal conduction. Air gap disturbs the thermal conduction as air is a really poor thermal conductor with a thermal conductivity of 0.026 W/mK at room temperature. Air acts as a thermal barrier preventing the effective heat transfer between the heat source and heat sink. Different kind of thermal interface materials are used to fill up the air gap between the heat generator and the heat sink to improve thermal conduction. Introduction of thermal interface material can significantly increase the performance of electronic device. In a typical power electronic package, a grease is used as thermal interface material. Thermal conductive paste with high thermal conductivity (much greater than air) fills up all the air gaps between the heat generator and the heat sink to improve the thermal conduction. Development of the thermal conductive paste with low thermal resistance, high thermal conductivity and low electric conductivity is challenging and the most important aspect in today's electronic industries. In the current study, we have tried to overcome this challenge by developing a thermally conductive grease with low thermal resistance, high thermal conductivity and low (open full item for complete abstract)

Committee: Jiahua Zhu PhD (Advisor); Rajeev Gupta PhD (Committee Member); Zhenmeng Peng PhD (Committee Member) Subjects: Chemical Engineering; Engineering; Polymers

Doctor of Philosophy, University of Akron, 2017, Polymer Science

Geckos are intriguing creatures, adhering to ceilings, to leafs, to glass and cement, all without glue. Instead, their adhesion is dependent on surface interactions between their hierarchical adhesive structure and the contacting substrates. These interactions on the nanoscale have significant macroscale influences. Changing the conditions between substrate and the nanostructures of the gecko adhesive affects the ability of geckos to adhere. Improving our understanding of how these conditions affect the adhesion of the natural gecko system can then inform our synthetic adhesive design efforts. Here, I have investigated how geckos perform on 'soft' substrates and on rough underwater substrates. Taking inspiration from the hierarchical nanostructure of the gecko adhesive, and its interactions with water, hierarchical rough carbon nanotube substrates were used to investigate the roles of roughness and surface chemistry on superhydrophobic stability. The 3D structure of CNTs was further used to investigate the influence of surface interactions on the macroscale thermal conductivity properties.

Committee: Ali Dhinojwala Dr. (Advisor); Yu Zhu Dr. (Committee Chair); Gary Hamed Dr. (Committee Member); Mesfin Tsige Dr. (Committee Member); Peter Niewiarowski Dr. (Committee Member) Subjects: Condensation; Experiments; Nanoscience; Physics; Polymers; Zoology