The Preparation Of Nickel-Coated Conducive PET Fiber And The Application Study On EMI Shielding Properties

In this dissertation, two conductive PET fibers have been prepared by chemical plating nickel and electroplating nickel, and the composites with shielding electromagntic interference capacity have been prepared by blending conductive PET fibers with epoxy resin (EP) and cement matrix,respectively. The relations of mechanical properties and electromagnetic interference shielding properties to the conductive fiber content have been investigated. Simultaneously, surface component of the conductive fiber and surface tension of conductive fiber and matrix are measured. The main contents are as follow: 1.Electromagnetic interference shielding and conductive mechanism of the conductive composites were thoroughly reviewed, and some kinds of conductive fillers which were used to shield EMI were summarized. 2. Prepared methods of the conductive PET fibers and properties (electrical, mechanical and shielding EMI) of composites have been studied. It has been demonstrated that the ultrasonic chemical plating nickel could get better adhesion on the PET fiber than that of electroplating nickel. Excellent conductive properties and effectiveness for shielding EMI can be acquired by adding a spot of chemical plating nickel fibers in matrix. When the fiber content is 3 wt %, the mechanics properties of the conductive fiber/ EP composite is the best, and the composite also has good conductive ability. When conductive fiber content reaches 5 wt% ,the volume resistivity of composite is 0.43 Ω· cm and have good effectiveness for shielding EMI. 3. Surface components of nickel-coated fibers were determined by XPS. The content of nickel in the nickel coating which handled by ultrasonic electroless deposition techniques is over 99.5 wt %, and the conductive ability is better than conventional electroplate method. 4. The soakage ability of EP to the conductive fiber was improved by adding coupling agent (organic titanate and silane) to deal with conductive fibers. Research for the performance of composite showed that the mechanical properties of composite have been improved greatly, but the electrical conductive properties of composite have not been improved.5. The positive temperature coefficient (PTC) of nickel-coated PET fibers/EP composite has been studied, the composite have certain PTC effectiveness when adding 1.5 wt % conductive fibers to fill EP. Several hot circulating tests to composite have discovered the composites have very good thermal stability. 6. When using conductive fiber to fill cement matrix, the surface resistance of the composite material was 107 Ω, and its volume resistivity droped to 89 Ω · cm when the content of conductive fibers is 3 wt %, mechanical properties also have a certainty improved simultaneously. But because of the alkalescence of cement, the cement has very strong oxidation to the nickel coating, and reduced the conductivity properties of the composite.