奈米無機物包覆碳奈米管/環氧樹脂複合材料之製備及其性質之研究

Preparation and characterization of nano-inorganic materials coated carbon nanotube /epoxy composites

楊士億(Shin-Yi Yang)

指導教授 ： 馬振基

國立清華大學/工學院/化學工程學系/碩士(2009年)

摘要

本研究主要分成三部分，第一部分為探討介面絕緣之多壁碳奈米管(MWCNTs)包覆技術，首先藉由Friedel-Crafts Acylation對多壁碳奈米管進行表面改質，分別接枝上Benzenetricarboxylic acid (BTC)與gallic acid (GA)，並藉由拉曼光譜 (Raman Spectrum)、高解析電子能譜儀 (XPS)、紅外線光譜儀(FT-IR) 進行定性分析，以TGA作定量分析，接者藉由醯胺化反應使BTC-MWCNT與GA-MWCNT接枝上(3-Isocyanatopropyl) triethoxysilane (ICPES)，進一步以3-Aminopropyl trimethoxysilane (APTES) 與Aluminium isopropoxide(ALIP)來進行不同無機氧化物之溶膠凝膠法包覆碳奈米管以達到絕緣性之目的， 在此部分探討(1)Friedel-Crafts Acylation　對碳奈米管的結構影響，(2)接枝上不同單體對後續無機物包覆型態之影響，(3)包覆奈米無機物之碳奈米管對其電性與分散性質之影響。
　　由Raman光譜的分析可知未改質的碳奈米管有最低的D band/G band積分面積相對比值(1.08)，因其結構性最為完整，而經過酸氧化改質碳奈米管其由於酸洗改質碳奈米管表面時，穩定六員環會被硝酸氧化破壞造成環型開環，使得D band/G band積分面積相對比值大幅上升(1.29)。而Friedel-Crafts acylation改質之碳奈米管的D band/G band積分面積與未改質碳奈米管之相對比值上並沒有明顯的變化(1.12與1.09)，表示其除了可以有效改質碳奈米管，更可以保持碳奈米管之結構完整性 。
　　由TEM觀察可知，經由接枝ICPES的碳奈米管可以有效提升碳奈米管與無機前驅物水解後之膠體粒子的化學親合性，使得改質之碳奈米管導入膠體溶液後可以形成奈米級無機物包覆之碳奈米管，而深入比較兩系統之不同的官能基對ICPES的反應性差異，進而之對後續無機前驅物膠體粒子之親合性不同，使得在無機物包覆型態上的完整性出現差異，二氧化矽與三氧化二鋁包覆ICPES-BTC-MWCNT 的厚度約為7~20nm，並呈現部分連續性的包覆，而二氧化矽與三氧化二鋁包覆ICPES-BTC-MWCNT 的厚度約為5~15nm，並呈現部分均勻且連續性的包覆型態。
由溶劑分散性測試可知，無機物包覆之碳奈米管可以在THF溶劑中保持良好之懸浮分散性，本研究之介面包覆技術除了可以包覆奈米級無機氧化物於碳奈米管表面亦可以同時官能基化碳奈米管。
　　由導電性量測分析可知，無機物包覆在碳奈米管表面可以有效抑制粉末之導電性，在二氧化矽與三氧化二鋁包覆ICPES-BTC-MWCNT粉末電阻上升約106Ω*cm，而二氧化矽與三氧化二鋁包覆ICPES-BTC-MWCNT粉末電阻上升約108Ω*cm。

　　第二部分主要在導入一系列改質之碳奈米管於環氧樹脂之中，製備碳奈米管/環氧樹脂複合材料，並比較不同種類之碳奈米管在不同添加量下(0、1、3、5phr)對於複合材料之熱傳導性質、電性質與熱膨脹性質之影響。
本研究使用三氧化二鋁包覆之碳奈米管導入環氧樹脂形成複合材料後，在導電度測量方面，環氧樹脂在導入5phr三氧化二鋁包覆之碳奈米管其體積電阻可維持在1.29*1014~5.78*1015Ω*cm ；加入5phr包覆之碳奈米管其介電常數可以維持在3.72~4.56；玻璃態熱膨脹係數由66.44 ppm/oC下降到52.5~45.1ppm/oC (下降21~32%)，橡膠態熱膨脹係數由253.1 ppm/oC下降到215~201.1ppm/oC (下降15%~20.5%)；在熱傳導測量方面，其導熱度由0.13 W/mK上升到1.01~1.1W/mK(上升677~746%)。

　　第三部分的研究旨在將三氧化二鋁包覆之碳奈米管添加在三氧化二鋁/環氧樹脂形成三成分複合材料，以製備絕緣導熱之熱介面材料，並在此部分與商業化配方之無機粉添加量去做比較，探討包覆碳奈米管導入三氧化二鋁/環氧樹脂複合材料對其三元摻混複合材料之熱傳導性質、電性質與熱膨脹性質之影響。

關鍵字

奈米碳管 ； 環氧樹脂 ； 奈米複合材料 ； 熱介面材料

並列摘要

The objectives of this research are the preparation and characterization of poymer composite for the use in thermal interfacial materials (TIM). There are three parts in this study.
The first part of this research is to develope the surface coating technologies for using these MWCNTs to template the assembly of silica and alumina nanoparticle. At first, the functionalized multi-walled carbon nanotubes (MWCNTs) were prepared via Friedle-Crafts acylation with Benzenetricarboxylic acid and Gallic acid. Raman spectra and X-ray photoelectron spectroscope (XPS) were utilized to characterize the functionalization of MWCNT.Thermogravimetric analysis (TGA) was used to calculate the organic contents of Benzenetricarboxylic acid and Gallic acid grafted MWCNT (BTC-MWNT and GA-MWCNT), which were 20.1wt% and 7.03wt%, respectively. Second, silane functionalized BTC-MWCNT and GA-MWCNT were prepared via amidation with (3-isocyanatopropyl) triethoxysilane. Raman spectra and X-ray photoelectron spectroscope (XPS) were utilized to characterize the functionalization of MWCNT. The ICPES-BTC-MWCNT and ICPES-GA-MWCNT were utilized as the nano-catchers for inorganic nanoparticles by the covalent incorporation between the silane functionalized MWCNTs and inorganic nanoparticles. The nano silica layer and nano alumina layer coated on the surface of MWCNTs can prohibit the conductive path of electrons. This part intends to investigate (1)the effect of functionalization on the structure of the MWCNTs by Friedel-Crafts modification；(2)the difference in the reactivity of functional groups on the surfaces of MWCNTs affect the morphology of inorganic nanoparticles coated on the MWCNTs；(3)the electrical properties and dispersion of inorganic nanolayer coated the MWCNTs.
The ID/IG area ratio of prinstine-MWCNTs, acid treated MWCNTs, BTC-MWCNTs and GA-MWCNTs are 1.08, 1.29, 1.12 and 1.09, respectively. The ID/IG values of BTC-MWCNTs and GA-MWCNTs indicate this modification will functionalize the MWCNTs with slightly or no damage on the structure of MWCNTs.
The morphology of inorganic nonoparticles coated on the surface of MWCNTs can be observed by TEM. The coating thickness of SiO2@BTC-MWCNT and Al2O3@BTC-MWCNT are about 7~20nm. The morphology exhibits partially continuous coating, and the silica layer is more smooth than alumina layer. The coating thickness of SiO2@GA-MWCNT and Al2O3@GA-MWCNT are about 5~15nm and the morphology exhibits more continuous coating than those of BTC-MWCNT series.
The volume resistivities of SiO2@BTC-MWCNT and Al2O3@BTC-MWCNT increased 106Ω*cm comparising with prinstine-MWCNT (4.71Ω*cm). The volume resistivities of SiO2@GA-MWCNT and Al2O3@GA-MWCNT increased 108Ω*cm comparising with prinstine-MWCNT. Results confirm that the nano silica layer and nano alumina layer coated on the surface of MWCNTs can prohibit the electrical conductive path　effectively.

The second part of this research discusses the preparation and characteration of functionalized MWCNTs/epoxy composites. This study investigates the electrical property, dielectrical property, thermal property and thermal conductivity of nanocomposites with various contents of MWCNTs in epoxy matrix.
The nanocomposite was prepared with 5phr Al2O3@MWCNTs. The volume resistivity and dielectrical constant of the Al2O3@MWCNTs/epoxy composite were 1.29*1014~5.78*1015Ω*cm and 3.72~4.56, respectively. The glass state CTE α1(coefficient of thermal expansion) and rubber state CTE of the Al2O3@MWCNTs/epoxy composite was decreased from 66.44 ppm/oC to 52.5~45.1ppm/oC (decreased 21~32%) and was decreased from 253.1 ppm/oC to 215~201.1 ppm/oC (decreased 15~20.5%), respectively. The thermal conductivity of the Al2O3@MWCNTs/epoxy composite was increased from 0.13 W/mK to 1.01~1.1W/mK (increased 677~746%).

The third part of this research illustrates the preparation and characterization of functionalized MWCNTs/ alumina/ epoxy composites. This study investigates the electrical property, dielectrical property, thermal property and thermal conductivity of the hybrid composites with nano and micro fillers.
The hybrid composite was prepared with 5phr Al2O3@MWCNTs、20Vol% alumina and 80Vol% epoxy matrix. The volume resistivity and dielectrical constant of the Al2O3/Al2O3@MWCNTs/epoxy composite were 8.4723*1013~2.1991*1015Ω*cm and 4.41~4.69, respectively. The glass state CTE (coefficient of thermal expansion) and rubber state CTE of the Al2O3@MWCNTs/epoxy composite decreased from 50.16 ppm/oC to 40.27~40.58ppm/oC (decreased 21~32%) and decreased from 201.4 ppm/oC to 143~162.7 ppm/oC (decreased 19~29%), respectively. The thermal conductivity of the Al2O3@MWCNTs/epoxy composite increased from 0.13 W/mK to 1.52~1.95W/mK (increased 1069~1400%). The enhancement of thermal conductivity of hybrid composite was more significant comparising with 60Vol% alumina/ epoxy composite (1.58 W/mK). The overall performance of hybrid composite with nano and micro fillers exhibited sinficant improvement.

並列關鍵字

carbon nanotube ； epoxy ； nanocomposites ； thermal interficial material

參考文獻

[1] S. ijima, Helical microtubules of graphitic carbon Nature , 1991, 354

[5] 梁麗娜, 國立清華大學化學工程學系論文, 2007 馬振基教授指導

[6] 楊子慧, 國立清華大學化學工程學系論文, 2007 馬振基教授指導

[9] C. C. Riccardi, and R. J. J. Williams, Journal of Applied Polymer Science, 1986, 32, 3445,

[12] S. Ijima, Helical microtubules of graphitic carbon Nature 1991, 354