THERMAL CONDUCTIVITY ENHANCEMENT OF MWNTS ON THE

THERMAL CONDUCTIVITY ENHANCEMENT OF MWNTS ON THE - Journal...

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Introduction Organic phase change materials (PCMs) are a kind of very important latent heat energy storage materials [1] and can be applied in lots of fields such as thermal energy storage [1], thermal protection [2] and heat transfer fluid [3], but their thermal conductivity is so low that limits their application. Numerous methods [4, 5] have been proposed to enhance their thermal conductivity but great efforts are still needed in this field. Carbon nanotubes (CNTs) possess wonderful thermal conductivity. Ultra-high thermal conductivity of single-walled carbon nanotubes (SWNTs) (~6600 W m –1 K –1 ) [6] and multi-walled carbon nanotubes (MWNTs) (3000 W m –1 K –1 ) [7] has been reported. The incredible high thermal conductivity of CNTs has induced great interest to apply it as thermal conductive filler [8–10]. But it was mainly focused on the field in which polymer or ceramic was used as matrix. To the best of our knowledge, though PCM/CNTs thermal interface materials were investigated [11], no bulky PCM/CNTs system has been reported because of the difficulty of maintaining the uniformity of CNTsdispersedinmeltedPCM . One feasible way to solve this problem might be dispersing the CNTs into form-stable PCMs. A form-stable PCM would keep its shape even it is heated to beyond the melting point of the solid-liquid PCM, which is dispersed in the supporting material [12]. When the CNTs are dispersed into it, the aggregation and the precipitation of CNTs would be negligible due to the existence of supporting material. We have found that PCM containing polyaniline (PANI) results in a new kind of form-stable PCM. Here we apply 1-Tetradecanol (TD) as PCM and PANI as supporting material, a series of form-stable PCM/MWNTs composites were prepared and the effect of the MWNTs on the thermal conductivity of the form-stable PCM was investigated. Experimental Materials The MWNTs with outer diameter of 10–30 nm and length of 5–15 m m were obtained from Shenzhen Nanotech Port Co., Ltd (Shenzhen, China). Aniline was redistilled under reduced pressure. All other reagents were of analytical grade and used as received. Preparation of the composites Aniline (1.0 g), concentrated HCl (1 mL) and cetyltrimethyl ammonium bromide (CTAB) (0.03 g) were dissolved in 90 mL water. Different amounts of MWNTs (0.01, 0.02, 0.05 and 0.1 g) were added to the solution and ultrasonicated for 1 h. Then 1.0 g TD was added to the above solution and the mixture was vigorously stirred for 2 h in a 50°C water bath to form an emulsion. The water bath was cooled to room temperature and replaced by an ice-water bath while the stirring continued. After the temperature of the mixture was cooled to 0–5°C, 10 mL of water solution containing 2.3 g ammonium persulfate was poured into it. The mixture was stirred 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2007 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 443–446 THERMAL CONDUCTIVITY ENHANCEMENT OF MWNT S ON THE PANI/TETRADECANOL FORM-STABLE PCM J. L. Zeng 1,2 ,Y .Y .Liu 1, 2 ,Z .X .Cao 1,2 , J. Zhang 1,2 , Z. H. Zhang
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This note was uploaded on 03/18/2012 for the course PHYSICS 303 taught by Professor Ihn during the Spring '12 term at Swiss Federal Institute of Technology Zurich.

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THERMAL CONDUCTIVITY ENHANCEMENT OF MWNTS ON THE - Journal...

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