發(fā)布時(shí)間：2018-01-30 23:37

  本文關(guān)鍵詞： 復(fù)合碳納米管 納米流體 懸浮穩(wěn)定性 導(dǎo)熱率　出處：《武漢理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：碳納米管具有質(zhì)輕、導(dǎo)熱性高等優(yōu)點(diǎn),由其制備的納米流體是一類新型強(qiáng)化傳熱流體,在材料、機(jī)械、電子等等領(lǐng)域具有巨大的應(yīng)用前景。目前,阻礙碳納米管納米流體工程應(yīng)用的重大瓶頸之一是碳納米管與基液相容性差、難以分散成均勻懸浮液,產(chǎn)生團(tuán)聚、沉淀,堵塞流通管道。因此,研究提高碳納米管流體的穩(wěn)定性和導(dǎo)熱率的工藝和機(jī)理,具有重要理論意義和應(yīng)用價(jià)值。本文針對(duì)碳納米管與基液乙二醇(EG)相容性差,懸浮穩(wěn)定性差的問題,探索了一種通過在碳納米管的表面接枝聚乙二醇支鏈,合成復(fù)合碳納米管的新方法。首先,通過配制濃硫酸與濃硝酸混合溶液處理碳納米管,制備表面功能化碳納米管;然后,通過在表面功能化碳納米管表面接枝聚乙二醇,得到復(fù)合碳納米管。并采用紅外光譜,掃描電鏡,熱重分析,XRD,比表面積和元素分析等等手段對(duì)復(fù)合碳納米管表面結(jié)構(gòu),表面性質(zhì),表面接枝有機(jī)物含量,晶型,比表面積及元素種類等進(jìn)行表征。實(shí)驗(yàn)結(jié)果表明:碳納米管表面成功接枝了聚乙二醇分子,其接枝量大于20%,粒徑增大約5-10nm。并且,通過表面接枝沒有改變碳納米管的晶體結(jié)構(gòu)。以合成的聚乙二醇原位接枝改性的復(fù)合碳納米管和乙二醇為原料,制備了乙二醇基復(fù)合碳納米管流體。采用熒光顯微鏡,觀察到復(fù)合碳納米管能夠較好地分散在基液乙二醇中;采用旋轉(zhuǎn)流變儀分析其流變特性;采用導(dǎo)熱率測(cè)試儀測(cè)試其導(dǎo)熱率和穩(wěn)定性。實(shí)驗(yàn)結(jié)果表明:復(fù)合碳納米管納米流體的穩(wěn)定性和導(dǎo)熱率得到顯著增強(qiáng)。其導(dǎo)熱率增強(qiáng)率隨體積分?jǐn)?shù)的增加而升高,并且隨溫度升高而顯著提高,粘度隨溫度升高而明顯降低。分析復(fù)合碳納米管納米流體的穩(wěn)定性和導(dǎo)熱率增強(qiáng)的機(jī)理,其中最重要的機(jī)制是碳納米管表面接枝聚乙二醇后,賦予碳納米管表面與基液乙二醇相同的分子結(jié)構(gòu),碳納米管表面接枝的聚乙二醇支鏈可以與基液乙二醇相容,并伸展到基液乙二醇中,從而提高了碳納米管和基液的分散穩(wěn)定性,并且減少了團(tuán)聚和纏繞,因此,碳納米管在基液乙二醇中的布朗運(yùn)動(dòng)就更快,導(dǎo)致導(dǎo)熱率升高。
[Abstract]:Carbon nanotubes (CNTs) have the advantages of light weight and high thermal conductivity. The nanofluids prepared by CNTs are a new type of enhanced heat transfer fluids, which have great application prospects in the fields of materials, machinery, electronics and so on. One of the major bottlenecks hindering the engineering application of CNTs is the poor compatibility between CNTs and the base solution, which makes it difficult to disperse into uniform suspensions, to produce agglomeration, to precipitate, and to block the flow pipes. It is of great theoretical significance and practical value to study the process and mechanism of improving the stability and thermal conductivity of carbon nanotubes. In this paper, the compatibility of carbon nanotubes with ethylene glycol (EGG) is poor. A new method of synthesizing composite carbon nanotubes by grafting polyethylene glycol branched chain onto the surface of carbon nanotubes was explored. Surface functionalized carbon nanotubes were prepared by preparing concentrated sulfuric acid and concentrated nitric acid mixed solution to treat carbon nanotubes. Then, the composite carbon nanotubes were prepared by grafting polyethylene glycol onto the surface of the functionalized carbon nanotubes, and were characterized by infrared spectroscopy, scanning electron microscope and thermogravimetric analysis (TGA). Specific surface area and elemental analysis were used to analyze the surface structure, surface properties, surface grafted organic content and crystal form of composite carbon nanotubes (CNTs). The experimental results showed that the surface of carbon nanotubes was grafted with polyethylene glycol, the grafting amount was more than 20 and the particle size increased about 5-10 nm. The crystal structure of carbon nanotubes was not changed by surface grafting. The composite carbon nanotubes and ethylene glycol modified by in situ grafting of polyethylene glycol were used as raw materials. The ethylene glycol based composite carbon nanotube fluid was prepared and the fluorescence microscope was used to observe that the composite carbon nanotube could be dispersed in the base liquid ethylene glycol. The rheological characteristics were analyzed by rotating rheometer. The thermal conductivity and stability of composite carbon nanotube nanofluids were measured by thermal conductivity tester. The results showed that the stability and thermal conductivity of composite carbon nanotube nanofluids were significantly enhanced, and the enhancement rate of thermal conductivity increased with the increase of volume fraction. The stability and thermal conductivity of composite carbon nanotube nanofluids were analyzed. The most important mechanism is that the surface of carbon nanotubes is grafted with polyethylene glycol and the surface of carbon nanotubes is endowed with the same molecular structure as the base liquid ethylene glycol. The branched polyethylene glycol chains grafted on the surface of carbon nanotubes can be compatible with the base liquid ethylene glycol and extend to the base liquid ethylene glycol, thus improving the dispersion stability of carbon nanotubes and the base solution, and reducing the agglomeration and winding. The Brownian motion of carbon nanotubes in the base liquid ethylene glycol is faster, resulting in higher thermal conductivity.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ127.11;TB383.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 江盛玲;齊士成;員榮平;張孝阿;李娟;呂亞非;;碳納米管功能化的途徑、機(jī)理和表面特征[J];當(dāng)代化工;2014年08期

2 王振;武衛(wèi)東;周志剛;;納米流體強(qiáng)化微尺度換熱的研究進(jìn)展[J];應(yīng)用化工;2014年07期

3 楊波;王姣;劉軍;;碳納米流體強(qiáng)化傳熱研究[J];強(qiáng)激光與粒子束;2014年05期

4 宣益民;;納米流體能量傳遞理論與應(yīng)用[J];中國(guó)科學(xué):技術(shù)科學(xué);2014年03期

5 周登青;吳慧英;;乙二醇基納米流體黏度的實(shí)驗(yàn)研究[J];化工學(xué)報(bào);2014年06期

6 何欽波;汪雙鳳;曾社銓;鄭兆志;;直接吸收式太陽能集熱納米流體輻射特性實(shí)驗(yàn)研究[J];制冷學(xué)報(bào);2014年01期

7 ;Carbon nanotube glycol nanofluids: Photo-thermal properties, thermal conductivities and rheological behavior[J];Particuology;2012年05期

8 陳立飛;;含碳納米管納米流體制備及其性能研究[J];上海第二工業(yè)大學(xué)學(xué)報(bào);2011年02期

9 溫春婭;李光磊;孫雪玲;;碳納米管的改性及其應(yīng)用[J];當(dāng)代化工;2010年02期

10 陳立飛;吳峰;張暉;沈松峰;;碳納米管表面羥基化及其納米流體的導(dǎo)熱性能研究[J];上海第二工業(yè)大學(xué)學(xué)報(bào);2009年02期

相關(guān)博士學(xué)位論文 前3條

1 趙江;高質(zhì)量多壁碳納米管的制備方法和應(yīng)用研究[D];上海交通大學(xué);2013年

2 楊應(yīng)奎;聚合物修飾多壁碳納米管的合成、結(jié)構(gòu)與性質(zhì)[D];華中科技大學(xué);2007年

3 李強(qiáng);納米流體強(qiáng)化傳熱機(jī)理研究[D];南京理工大學(xué);2004年

相關(guān)碩士學(xué)位論文 前8條

1 楊雯瑾;布朗運(yùn)動(dòng)影響下二維及三維方腔內(nèi)納米流體自然對(duì)流換熱數(shù)值研究[D];蘭州理工大學(xué);2014年

2 賈濤;水基納米流體的制備及其熱物理特性實(shí)驗(yàn)研究[D];北京建筑大學(xué);2014年

3 趙展;碳納米管分散性的研究[D];東華大學(xué);2014年

4 高宇飛;碳納米管導(dǎo)熱性能的分子模擬研究[D];哈爾濱工業(yè)大學(xué);2009年

5 倪楊;納米強(qiáng)化傳熱導(dǎo)熱油的制備研究[D];南京理工大學(xué);2009年

6 蘇小紅;碳納米管類流體的制備及特性研究[D];武漢理工大學(xué);2007年

7 鄭立國(guó);碳納米管—水納米流體重力熱管傳熱性能研究[D];浙江大學(xué);2007年

8 楊畫春;納米流體強(qiáng)化傳熱特性的研究[D];青島科技大學(xué);2007年

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