Temperature dependent reinforcement efficiency of carbon nanotube in polymer composite Dinesh Kumar Rathore n , Bhanu Pratap Singh, Sarat Chandra Mohanty, Rajesh Kumar Prusty, Bankim Chandra Ray Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008, India article info Article history: Received 20 June 2016 Received in revised form 16 August 2016 Accepted 18 August 2016 Keywords: Carbon nanotube Nanocomposite Interface/Interphase Elevated temperature abstract The transcendent mechanical properties of carbon nanotube (CNT) hold the promise of delivering con- tributory reinforcing effect in soft polymeric materials. But, the built-in-risk of the environmental sus- ceptibility of the CNT/polymer interface should be well explored before certifying it for a particular application. Present investigation reports the reinforcement efficiency of CNT in epoxy as a function of environmental temperature. Nanocomposite with 0.2% CNT, which shows maximum strength and modulus at room temperature, exhibits the poorest strength and modulus at 90 °C. Dynamic mechanical thermal analysis (DMTA) has also been carried out to study the variation of thermomechanical properties of nanocomposites with temperature. A decrement in the glass transition temperature (T g ) of the polymer was obtained due to CNT reinforcement upto 0.2%. Post-failure fracture surface analysis was done to underneath the dominating strengthening, toughening and weakening mechanisms. & 2016 Elsevier Ltd. All rights reserved. 1. Introduction Replication of the unique properties of the carbon nanotube in the polymer is the key target to achieve superior mechanical, thermal and/or electrical properties of the materials. Many re- search articles have reported the beneficial mechanical perfor- mance of CNT reinforced polymers at room temperature [1]. Var- ious environmental parameters have been reported to influence the mechanical behavior of polymeric composites [2]. Addition of CNT into polymeric materials has shown remarkably improved cryogenic mechanical performance [3]. But to the best of our knowledge there is a dearth of open literature on the mechanical performance of such CNT embedded polymer composite when the service temperature is relatively high. These nanocomposites are potential materials for applications like EMI shielding, where there is a significant chance of internal heat generation, leading to substantial temperature increment in the material [4]. So, the performance of the material must be well ensured to avoid any unprecedented failure. “Whether the strength enhancement me- chanism still remains valid at elevated temperatures and what is the role of CNT content in the nanocomposite on its elevated temperature durability”, these two questions have been tried to answer in the current paper. 2. Experimental procedure Epoxy resin used in this study was diglycidyl ether of Bisphenol A (DGEBA) and hardener was Triethylene tetra amine (TETA), both were supplied by Atul Industries, India under the trade name La- pox, L-12 and K-6 respectively. The MWCNT used has an outer diameter 6-9 nm, length 5 μm, purchased from Sigma Aldrich, USA. Preweighed amount of CNT (0.1, 0.2, 0.3wt% of epoxy) was added to acetone and then stirred at 1000 rpm for 30 min fol- lowed by 30 min sonication. This mixture was then added to epoxy and stirred at 70 °C and 1000 rpm until entire acetone was evaporated, followed by 1 h sonication at 70 °C. The suspension was kept under vacuum for 18 h. Then, to the suspension, required amount of hardener (10% of epoxy) was mixed properly and poured into moulds. Neat epoxy (with hardener) was also poured in similar moulds. These moulds were kept in vacuum for 10 min followed by room temperature curing for 24 h. The samples were removed from the moulds carefully and well-polished to have better surface finish and uniform geometry. The final samples were then post cured at 120 °C for 6 h. 3-point flexural tests were carried out (ASTM D790) using UTM (Instron 5967) attached with environmental chamber at various temperatures with loading rate 1 mm/min with 10 min holding at each temperature. In DMTA (Netzsch DMA242E) samples were loaded on a 3-point bending fixture and heated from 40 °C to Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/coco Composites Communications http://dx.doi.org/10.1016/j.coco.2016.08.002 2452-2139/& 2016 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail address: dineshrathore2603@gmail.com (D.K. Rathore). Composites Communications 1 (2016) 29–32