| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 106 === The first topic of this thesis is the development of polymer with anti-yellowing property. The development of durable paint is investigated continuously to meet industrial needs. The yellowing phenomenon over paint is resulted from the UV-photolysis of polymer. In this study, graphene oxide and surface-modified graphene oxide were grafted onto polymethyl methacrylate (PMMA) to improve its yellowing resistance due to the graphene oxide exhibits the excellent UV-absorption property. The work was divided into three stages. Firstly, the graphene oxide was modified with glycidyl methacrylate to improve its degree of dispersion. Secondly, the graphene/PMMA copolymer with an appropriate molecular weight was synthesized via a free-radical copolymerization method. Finally, the characteristics of the copolymer coatings and properties of modified graphene oxide were studied in detail, such as dispersion, absorption of ultraviolet light, yellowing resistance, thermal stability, and salt resistance. The results showed that the modified graphene oxide/PMMA film with obvious UV-absorption property exhibited the good yellowing resistance reasonably. Moreover, this copolymer coating also improved the salt resistance of iron plates.
The silicone conductive paste was the second topic of this thesis. The influence of electromagnetic waves on electronic components need to be reduced for the enhancement of stability and operation speed for various types of communications, electronic devices and products. Therefore, the development of electromagnetic shielding materials with high efficiency and thermal stability is an important issue. The preparation procedure of conductive paste with using silicone resin and silver-coated copper powder was investigated herein. The silver-coated copper powder with flake and spherical shape were respectively added to the silicone resin, and the contents of other additives were adjusted to obtain the optimal formula and process. The effects of solvents, silane coupling agents, reinforcing agents and manufacture process on conductive properties, electromagnetic shielding, and structural strength were studied systematically. It was found that the content of silver-coated copper powder should be more than 70 wt% for good conductive property. The conductive path made of conductive particles will be formed in the silicone rubber in the presence of appropriate amount of solvent. The dispersion of conductive particles was increased by using an isothermal agitation device. After using the pressurized filtration to remove the excess solvent, a conductive paste with a resistance less than 0.45 Ω and an electromagnetic shielding effect of 80 dB can be obtained, which is meet the industrial specification.
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