導電性及導磁性之電磁波屏蔽複合材料研究

The study of Conductive and Magnetic Composite Materials for Electromagnetic Shielding

邱瑞宗(Ruei-Tzung Chiue)

指導教授 ： 陳志恆

國立臺北科技大學/工程學院/材料及資源工程系所/碩士(2006年)

摘要

近年來，電子的產品及設計朝向電路高積體化、高速化、省功率化及小型化，使得產品在使用過程會產生高密度的電磁環境，因此對於產品的抗靜電、靜電放電（Electrostatic Disharge, ESD）防護及防電磁波干擾（Electromagnetic Interference, EMI）之功能要求相對的提高。因此，產品的設計須考量電磁相容性（Electromagnetic Compatibility, EMC），使系統不受雜訊影響，不產生雜訊，使其在正常的電磁環境下，才發揮應有之功能。特別是電磁波的干擾會造成工作元件產生錯誤訊號，降低產品的功能，另外，這些電磁波也可能對人體健康造成影響。
本研究為製備出具有導磁性及導電性之電磁波屏蔽複合材料。首先，以2-(4-chlorosulfonylphenyl)矽烷系偶合劑CTCS進行氧化鐵粉末（MP）及碳黑（CB）表面的改質，使用自行組裝單分子沉澱法使CTCS上的氯化矽chlorosilyl（-SiCl3）官能基與氧化鐵（MP）及碳黑（CB）表面的氫氧hydroxyl（-OH）官能基會反應形成Si-O-Fe或Si-O-C鍵結，在MP及CB表面接上CTCS，形成MP-CTCS及CB-CTCS，因此氧化鐵及碳黑表面帶有chlorosulfonyphenyl (-SO2Cl)官能基。
MP-CTCS表面帶有chlorosulfonyphenyl（-SO2Cl）官能基，所以可以適用於銅金屬調節的原子轉移自由基聚合法（ATRP）反應中，使氧化鐵表面接枝上聚甲基丙烯酸甲酯（PMMA），形成MP-PMMA，當聚合時間達24小時，PMMA之重量平均分子量Mw為37,209，數量平均分子量Mn為34,124，則分子量分布指數（polydispersity index, PDI）約為1.09。此時MP-PMMA具足夠的PMMA鏈長，使氧化鐵可穩定的分散在聚甲基丙烯酸甲酯（PMMA）之單體（MMA）中。
MP-PMMA末端的官能基再與MMA單體進行聚合反應而形成具有導磁性之電磁波屏蔽複合材料。經CTCS改質之碳黑在MMA單體中獲得良好的潤濕效果，藉由MP-PMMA的支撐下，在MMA中可達到足夠的穩定性分散。再以起始劑AIBN引發MMA單體的聚合反應而形成具有導電性及導磁性之電磁波屏蔽複合材料。

關鍵字

原子轉移自由基聚合法(ATRP) ； 碳黑 ； 氧化鐵 ； 導電性 ； 導磁性 ； 電磁波屏蔽複合材料

並列摘要

In recent year, the developments of electronic products and design are toward high level of integration, high speed, low power, and miniaturization. Consequently, the effects of high density electromagnetic noise on the performance of electronic products has become a major issue. Therefore, antireflection, electrostatic discharge (ESD) protection, and preventing electromagnetic interference (EMI) are important for better product performance. In order to avoid the interference of electromagnetic noise on system performance, the electromagnetic compatibility (EMC) needs to be considered during the design of the products. In addition, the high density electromagnetic wave may cause the health concerns.
In this study, the preparation of conductive and magnetic composite materials for electromagnetic shielding was investigated. The surfaces of magnetic ferric oxide particles (MP) and carbon black (CB) were first modified with CTCS (2-(4-chlorsulfonylphenyl)ethytrichlorosilane) by the self-assembled monolayer- deposition method. The surface hydroxyl groups of MP and CB can chemically bond with CTCS on particle surfaces to provide chlorsulfonylphenyl group for further living free radical polymerization of PMMA.
The chlorsulfonylphenyl groups are suitable for copper-mediated atom transfer radical polymerization (ATRP). Methyl methacrylate (MMA) was successfully grafted onto MP surfaces to form MP-PMMA. As the polymerization time is up to 24 hours, the number average molecular weights of grafts PMMA is 34,124, and the polydispersity index is 1.09. Due to the stabilization effect of grafted PMMA. MP-PMMA can be dispersed in MMA monomer solution with good stability.
The end functional group of MP-PMMA is chlorsulfonylphenyl groups form CTCS, which can carry on living free radical polymerization with MMA monomers to form magnetic composite materials for electromagnetic shielding. The surface of CB also can be modified with CTCS. Modified CB can posses good wetability in MMA solution. With the support of MP-PMMA, CB can be dispersed in PMMA to form conductive and magnetic composite materials for electromagnetic shielding.

並列關鍵字

Atom Transfer Radical Polymerization (ATRP) ； carbon black ； ferric oxide ； conductivity ； permeability ； composite materials of electromagnetic shielding

參考文獻

[3] Wenderoth K. J., Petermann K. D., Kruse and Haseborg J. L., ” Synergism on electromagnetic inductance (EMI)-shielding in metal- and ferroelectric-particle filled polymers,” polymer composites, Vol. 10 ,1989, pp. 67-82.

[13] Novak. I., Krupa. I., Chodak. I., “Investigation of the correlation between electrical conductivity and elongation at break in polyurethane-based adhesives,” Synthetic Metals., Vol. 131, 2002, pp. 93-98.

[15] Plastics Additives & Compounding, “New conductive carbon blacks offer electrostatic discharge and improved mechanical properties,” Plastics, Additives and Compounding, Vol. 5, no1, January-February 2003, pp. 28-33

[19] Cornelis Klein, MINERAL SCIENCE, Canada: John Wiley & Sons, 2002, pp374-375.

[20] 劉伊郎等，「氧化鐵（Fe3O4）薄膜與超晶格」，物理雙月刊，22卷6期，2000，十二月，第592-605頁。