- 學位論文
吸收型電磁波遮蔽奈米高分子複合材料之製備與研究
The Manufacture and Investigation of Nano-Polymeric Composites for Electromagnetic Interference Shielding by Absorption Electromagnetic Wave
摘要
本研究利用化學氧化聚合法，並加入陽離子界面活性劑溴化十六烷三甲基銨(CTAB)製備多層管壁奈米碳管(MWNT)-聚咇咯(PPy)複合材料，經由四點探針測試此複合材料具有高導電性之特點。故應用多層管壁奈米碳管-聚咇咯複合材料之導電特性，以混煉方式將其添加入高分子基材（Ethylene-Vinyl Acetate, EVA）中形成導電高分子複合材料，而具備電磁波遮蔽之效果。 針對改變複合材料之填充料含量、填充料之種類和試片厚度在電磁波遮蔽之影響。並利用SEM、FE-SEM、Raman、FTIR和TEM等分析，探討導電顆粒之導電性與粒徑大小及顆粒於基材內之分散情況等，來解釋導電性高分子複合材料於電磁遮蔽值之變化。 由實驗結果顯示，當多層管壁奈米碳管添加量為12phr於高分子基中，電磁波遮蔽值大約12dB。再利用多層管壁奈米碳管-聚咇咯複合材料添加入高分子基材中，此時聚咇咯含量75phr，多層管壁奈米碳管添加量保持12phr，其電磁波遮蔽值大幅提升至48~58 dB，且在入射波能量有10％之吸收效果。在相同多層管壁奈米碳管-聚咇咯複合材料添加量時，電磁波遮蔽值隨著試片厚度增加而增加，而電磁波反射損失則隨著試片厚度增加而減少；當試片厚度增加至4mm，電磁波遮蔽值可55-60 dB。
並列摘要
In this study, the Multiwalled carbon nanotube (MWNT)-Polypyrrole (PPy) composites were synthesized by chemical oxidative polymerization using cetyltrimethylammonium bromide (CTAB) as the cationic surfactant. The high electric conductivity of the composites could be affirmed by the measurement of 4-point-probe method. Then the MWNT-PPy conductive composites were used as conductive fillers and were blended with EVA (ethylene-vinyl acetate) pellets by the mixer (Brabender Plasti-Corder PLE-330) to form polymeric composites which owned the Electromagnetic Interference Shielding Effectiveness (EMI SE). The influences of filler contents, types of filler and sample thickness on the EMI SE of composites were investigated. The resistance, structural analysis and particle sizes of fillers, cross section morphology and MWNT-PPy composites dispersion and EMI SE of polymeric composites were detected by 4-point-probe method, SEM, FE-SEM, Raman, FTIR, EMI measurements, respectively. In this investigation, the EMI SE of the composite containing 18phr MWNT could reach 12 dB. However, EMI SE value could be improved obviously to 48~58dB as 75phr PPy was coated on 18phr MWNT; meanwhile, 10% of the power of the incident wave was absorbed by the composite. Under the same MWNT-PPy contents, the EMI shielding of the MWNT-PPy/EVA composite increased with an increasing thickness of composites, and its EMI SE was 50~60 dB at a sample's thickness of 4 mm. When the sample thickness increased, the reflection loss of electromagnetic wave was decreased; on the contrary, the transition loss of electromagnetic wave was increased.