Investigation of multi‐walled carbon nanotube‐reinforced high‐density polyethylene/carbon black nanocomposites using electrical,DSC and positron lifetime spectroscopy techniques |
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Authors: | Thimmaraju Jeevananda Nam Hoon Kim Joong Hee Lee Siddaramaiah Basavarajaiah MV Deepa Urs Chikkakuntappa Ranganathaiah |
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Affiliation: | 1. BIN Fusion Research Team, Department of Polymer and Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561‐756, South Korea;2. Department of Chemistry, R&D Centre, RNS Insttitute of Technology, Bangalore, 560 061, India;3. Department of Hydrogen and Fuel Cell Engineering, Chonbuk National University, Jeonju, Jeonbuk 561‐756, South Korea;4. Department of Polymer Science and Technology, Sri Jayachamarajendra College of Engineering, Mysore—570 006, India;5. Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore—570 006, India |
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Abstract: | BACKGROUND: The positive temperature coefficient (PTC) effect on material properties has attracted much attention in recent years due to the prospects of many applications like temperature sensors, thermistors, self‐regulating heaters, etc. It has been suggested that incorporation of multi‐walled carbon nanotubes (MWNTs) into carbon black (CB)‐filled polymers could improve the electrical properties of composites due to high conductivity and network structure and significantly reduce the required CB loading. RESULTS: We observed no change in melting temperature and crystalline transition temperature on addition of MWNTs. However, the heat of fusion decreases as the amount of conducting carboxylated MWNT (c‐MWNT) filler increases and the resistivity of the composite decreases. The free volume shows an increase up to 1.5 wt% of c‐MWNT content and then decreases. CONCLUSION: Well‐developed crystals could not be formed due to restricted chain mobility as filler content increases. This results in minimum intermolecular interactions, and thus a decreased heat of fusion. A composite with c‐MWNT content of 0.5 wt% showed the highest PTC and higher resistivity at 150 °C possibly due to the formation of flocculated structures at elevated temperature. For filler content greater than 1.5 wt%, the decrease in free volume may be due to restricted chain mobility. Copyright © 2009 Society of Chemical Industry |
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Keywords: | nanocomposite high‐density polyethylene carbon nanotubes positron annihilation free volume holes |
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