| Summary: | 碩士 === 淡江大學 === 機械工程學系 === 87 === In present research, ABS+20wt%PC/Al flakes metallized plastic pellets are produced by injection molding. Through the metallized plastic, the material microstructure and Al flakes distribution observations, mechanical properties and EMI shielding effectiveness tests are done under different conditions of melt temperature, injection parameter, coupling agent and Al flake width.
While the metallized plastic with 0.8mm Al flakes are injection molded in different melt temperatures (200℃, 240℃ and 270℃) and injection speeds (18%, 25% and 35%), it is found that aspect ratio is increased with the melt temperature and has no apparent relation with the injection speed. Then, according to the observation of the specimens for EMI shielding effectiveness test, low melt temperature and low injection speed gets small aspect ratio and well Al flake distributing in both core and skin layers of the matrix. On the contrary, high melt temperature and high injection speed forms big aspect ratio and bad distribution; namely, Al flakes distribute in the core more than in the skin layer of the matrix. According to the observation of the specimens for the tensile test, there are plenty of Al flakes clustered irregularly in the matrix because of the injection way of filling. The higher melt temperature is, the more seriously the situation of clustering is. According to the observation of the specimens for the impact test, the injection way of filling makes Al flakes in the matrix distribute in the shape of arc. High temperature makes the shape of Al flakes distribution irregular and the amount of Al flake different in the core and skin layers of the matrix.
Effects of different melt temperatures (270°C and 210°C), Al flakes widths (0.5mm and 0.8mm), and coupling agents (A-187 and A-1100) on the properties of ABS+20%PC/Al Flake metallized plastics are also discussed. According to experiments, it is found that aspect ratio is larger with the 270°C-melt temperature and 0.8mm Al flake, but it is decline with the A-187 coupling agent. 0.5mm Al flakes treated with A-1100 coupling agent at 270°C melt temperature has better distribution in matrix and EMI shielding effectiveness, but has smaller volume resistance. With 0.8mm Al flakes at 210°C melt temperature, and treated with A-1100 coupling agent has larger ultimate tensile strength and impact strength, respectively. At last, there is no relation between HDT and melt temperatures Al flake widths and coupling agents.
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