| Summary: | 博士 === 大同大學 === 材料工程研究所 === 90 === The high-coating-thickness electroless nickel carbon fiber (HENCF) with the designed structure which was composed of attached fragments on a dense layer has been fabricated. Owing to the lubricating behavior resulting from the attached fragments, HENCF absorbed most of the mechanical energy to avoid the fiber from breakage when they were compounded with plastics. The average aspect ratio of the HENCF, therefore, do not decreased significantly. Meanwhile, nickel/phosphorous (Ni/P) particles or flakes detached from the attached fragments of electroless nickel-coated carbon fibers (ENCF) were distributed uniformly in the zone between fibers and polymers; hence, a compact conductive network in the composite matrix was formed. Consequently, the mechanical properties and electromagnetic interference (EMI) shielding effectiveness (SE) were greatly improved. In addition, if the fibers were immersed into a dilute polymer solution immediately after the electroless plating processes, the mechanical properties and EMI SE of those conductive composites were enhanced.
Polytetrafluoroethylene (PTFE) powders were mounted in the electroless Ni/P film on the surface of carbon fiber (FENCF) by electroless co-deposit method. Although the adhesion between the electroless Ni/P-PTFE films and fiber was reduced, PTFE powders on the surface of FENCF reduced the torque values when compounded into the ABS matrix due to the self-lubricated effect. The 2-step FENCF composite had particularly significant benefits. Torque values of the 2-step FENCF/ABS composites were about one half of those for carbon fiber/ABS composites in compounding processes; in addition, the former had almost 2.5 times average mean fiber length than that of the later. The EMI SE of FENCF/ABS composites did not decrease significantly even though the PTFE powders form a discontinuous phase on electroless Ni/P films. The mechanical properties of FENCF composites were enhanced due to the larger fiber length.
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