Thermal Decomposition Behavior of Carbon Nanotube Reinforced Thermotropic Liquid Crystalline Polymers Sang Ho Park, 1 Seung Goo Lee, 2 Seong Hun Kim 1 1 Department of Fiber and Polymer Engineering, College of Engineering, Hanyang University, Sungdong-gu, Seoul 133-791, Korea 2 Department of Advanced Organic Materials and Textile System Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764, Korea Received 5 November 2010; accepted 22 January 2011 DOI 10.1002/app.34200 Published online 13 June 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Thermotropic liquid crystalline polymers (TLCP), 4-hydroxybenzoic acid (HBA)/6-hydroxyl-2-naph- thoic acid (HNA) copolyester, and HNA/hydroxylbenzoic acid (HAA)/terephthalic acid (TA) copolyester reinforced by carbon nanotube (CNT) were prepared by melt com- pounding using Hakke internal mixer. The thermal behav- ior and degradation of CNT reinforced HBA/HNA copolyester and HNA/HAA/TA copolyester have been investigated by dynamic thermogravimetric analysis under nitrogen atmosphere in the temperature range 30 to 800  C to study the effect of CNT on the thermal decomposition behavior of the TLCP/CNT nanocomposites. The thermal decomposition temperature at the maximum rate, residual yield, integral procedural decomposition temperature, and activation energy for thermal decomposition was studied to investigate thermal stability of TLCP/CNT nanocompo- sites. The thermal stability of CNT reinforced HBA/HNA copolyester was increased by addition of a very small quantity of CNT and the residual weight was 42.4% and increased until 50.8% as increasing CNT contents. How- ever, the thermal stability of CNT reinforced HNA/HAA/ TA copolyester was decreased initially when a very small quantity of CNT added. The residual weight was decreased from 50.4% to 45.1%. After addition of CNTs in the TLCP matrix, the thermal stability of CNT reinforced HNA/HAA/TA copolyester increased as increasing con- tent of CNT and the residual weight was increased until 53% as increasing CNT contents. The activation energy was calculated by multiple heating rate equations such as Friedman, Flynn-Wall-Ozawa, Kissinger, and Kim-Park methods to confirm the effect of CNT in two different TLCP matrices. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2060–2070, 2011 Key words: activation energy; degradation; liquid crystalline polymer; nanoparticles; thermogravimetric analysis (TGA) INTRODUCTION Polymer nanocomposites reinforced by nanofillers have received a great deal of attention from both sci- entific field and industry because of their outstand- ing improvements in the physical properties despite of low filler contents. There were various attempts to develop advanced polymer nanocomposites by incorporating various nanofillers into polymer ma- trix. Among many fillers, carbon nanotubes (CNTs) have been considered as promising agents in poly- mer matrix reinforcement because of its excellent properties such as high mechanical strength, electri- cal, and thermal conductivity with a high aspect ra- tio and a small size. 1–4 However, because of its high cost, there were only a few applications in the indus- trial fields. Therefore, the fabrication of the polymer nanocomposites reinforced by CNT should be required at cheap manufacturing costs. 5 There were a few processing techniques in common use to fabri- cate CNT/polymer nanocomposites: solution mixing or film casting, in situ polymerization, and melt com- pounding. 6–9 Among these processing techniques, melt compounding process has been considered as the most simple and effective technique because it was economic and industrial perspective to fabricate advanced nanocomposites at low cost. 10 Thermotropic liquid crystalline polymers (TLCPs) have outstanding mechanical properties, stiffness, good chemical resistance, and dimensional stabil- ity. 11–13 Because of these properties, TLCPs have been utilized as high-performance engineering plas- tics in various industrial fields where high thermal stability is required. 14,15 The thermal stability of polymers was very important for determining their processing and applications because it influences the final properties, such as dimensional stability and the upper limit use temperature. Therefore incorpo- ration of a small quantity of expensive CNTs into TLCP matrix with low processing cost provides a good possibility to improve the thermal stability and other physical properties of CNT reinforced polymer composites. 16,17 Correspondence to: S. H. Kim (kimsh@hanyang.ac.kr). Contract grant sponsor: National Research Foundation of Korea; contract grant number: 2010-0028182. Journal of Applied Polymer Science, Vol. 122, 2060–2070 (2011) V C 2011 Wiley Periodicals, Inc.