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Photo-Curable Electrical Contact Stabilization Materials

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2017, Doctor of Philosophy, University of Akron, Polymer Engineering.
Electrical contact surfaces can never be perfectly smooth or flat regardless of its manufacturing process. Due to the inevitable surface roughness, when areas of metal surfaces are meant to mate with other metal surfaces, the connection between them is less than ideal; there is only a small portion of the surface area truly connected. Electrical signal current can only flow through those actual connected areas, which generates surface resistance. This less than ideal connection causes the current flow to be unstable since any kind of vibration or movement can “break and re-attach” the connection points. As a result, the electrical noise and dynamic variations in resistivity of the connection are generated. Currently, there are some existing products which can act as electrical contact stabilization materials between two contact surfaces to improve the actual connection. However, they are either applied in a liquid state, which tends to be leaky and runny, or in the form of solutions with organic solvents, which causes large amount of chemical release and elongates the processing time. Hence, a series of photo-curable materials that were comprised of 100% reactive components were developed in this study. The first part of this study presents the development of photo-curable electrical contact stabilization materials along with their effects on the contact resistance of electrical connectors. The developed materials in this study were found to exhibit very comparable electrical performance as the traditional materials, which were able to decrease the contact resistance of custom-made gold-steel connections by approximately 5%. However, they are able to be cured to a gel state via UV-radiation, which stay permanently on the contact surfaces to prevent fluid problems. Furthermore, a series of LED-curable systems, which maintained similar electrical performance, were also developed for visible light curing options. The second part further investigates the photo-curing behavior of developed photo-curable electrical contact stabilization materials, with emphasis on their rheological properties, since they are the key factors determining the electrical performance. The effects of reactive diluents, including functionalities, molecular weight, and composition were investigated via a combination of dynamic rheological measurements and real time Fourier transform infrared (FT-IR) spectroscopy. The rheological properties including gel points and relaxation exponents were also classified by means of Winter-Chambon criteria and a gelation mechanism was proposed. The third study reveals the conduction mechanism of thin PEG-b-PPG-b-PEG dimethacrylate films, which is the major component of developed electrical contact stabilization materials. A systematic study about the effects of film thickness and temperature on the current (I)-voltage (V) characteristic of this material was carried out, which illustrated that its resistance significantly dropped to around 60 O when the film thickness reached 35.7 nm, which was ascribed to electron emission associated with high applied electric field. This significant increase in conductivity (compared to over 106 O at 141.2 nm) was proved to be the result of Schottky emission. The final study demonstrates the molecular structure of the developed ultraviolet (UV) curable electrical contact stabilization materials, which contain polyethylene glycol (PEG)-block-polypropylene glycol (PPG)-block-polyethylene glycol (PEG) capped with methacrylate functional groups on both ends as the reactive oligomers and a methacrylated PEG as the reactive diluent. The effects of reactive diluents, including functionalities and compositions were investigated via a combination of dynamic mechanical analysis, differential scanning calorimetry, FT-IR spectroscopy and wide angle X-ray diffraction. It was concluded that the molecular structure, along with the mechanical properties, glass transition temperature, degree of heterogeneity, and crystallization behavior of the cross-linked network was able to be manually adjusted by the proper selection of reactive diluents.
Miko Cakmak, Dr. (Advisor)
Mark Soucek, Dr. (Committee Chair)
Younjin Min, Dr. (Committee Member)
Darrell Reneker, Dr. (Committee Member)
Yilmaz Sozer, Dr. (Committee Member)
233 p.

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Citations

  • Wang, E. (2017). Photo-Curable Electrical Contact Stabilization Materials [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510574243243684

    APA Style (7th edition)

  • Wang, Enmin. Photo-Curable Electrical Contact Stabilization Materials . 2017. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1510574243243684.

    MLA Style (8th edition)

  • Wang, Enmin. "Photo-Curable Electrical Contact Stabilization Materials ." Doctoral dissertation, University of Akron, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510574243243684

    Chicago Manual of Style (17th edition)