Effect of carbon nanotube on PA6/ECO composites: Morphology development, rheological, and thermal properties Elnaz Esmizadeh , 1 Abdollah Irani, 2 Ghasem Naderi, 2,3 Mir Hamid Reza Ghoreishy, 2 Charles Dobious 3 1 Department of Polymer Science and Engineering, Faculty of Engineering, University of Bonab, Bonab 5551761167, Iran 2 Department of Rubber Processing and Engineering, Iran Polymer and Petrochemical Institute, Tehran 14965/115, Iran 3 Department of Chemical Engineering, Ecole Polytechnique Montr eal, Center for Applied Research on Polymers and Composites, CREPEC, Montreal, Quebec, Canada Correspondence to: G. Naderi (E - mail: G.Naderi@ippi.ac.ir) ABSTRACT: Thermoplastic elastomer (TPE) nanocomposites based on polyamide-6 (PA6)/poly(epichlorohydrin-co-ethylene oxide) (ECO)/multiwall carbon nanotube (MWCNTs) were prepared by melt compounding process. Different weight ratios of ECO (20, 40, and 60 wt %) and two kinds of functionalized and non-functionalized MWCNTs were employed to fabricate the nanocomposites. The morphological, rheological, and mechanical properties of MWCNTs-filled PA6/ECO blends were studied. The scanning electron microscopy of PA6/ECO blends showed that the elastomer particles, ECO, are well-dispersed within the PA6 matrix. The significant improvement in the dispersibility of the carboxylated carbon nanotubes (COOH-MWCNTs) compared to that of non-functionalized MWCNTs (non-MWCNTs) was confirmed by transmission electron microscopy images. The tensile modulus of samples improved with the addition of both types of MWCNTs. However, the effect of COOH-MWCNTs was much more pronounced in improving mechanical properties of PA6/ECO TPE nanocomposites. Crystallization results demonstrated that the MWCNTs act as a nucleation agent of the crystallization process resulted in increased crystallization temperature (T c ) in nanocomposites. Rheological characteriza- tion in the linear viscoelastic region showed that complex viscosity and a non-terminal storage modulus significantly increased with incorporation of both types of MWCNTs particularly at low frequency region. The increase of rheological properties was more pro- nounced in the presence of carboxylic (COOH) functional groups, in the other words by addition of COOH-MWCNTs. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45977. KEYWORDS: morphology; nanocomposites; polyamide-6; poly(epichlorohydrin-co-ethylene oxide); rheology; thermoplastic elastomers Received 20 July 2017; accepted 26 October 2017 DOI: 10.1002/app.45977 INTRODUCTION In the recent years, plastic and rubber blends known as thermo- plastic elastomeric materials (TPEs) have become commercially significant to use in order to that they have the combined prop- erties of thermoplastics and elastomers. 1,2 Actually TPE materi- als provide the properties of elastomers such as elasticity, high toughness, and low compression set in low temperature as well as the properties of plastics such as processability at high tem- perature. 3 Since these materials are not vulcanized so they can be recycle and re-shape via a re-melting process similar a ther- moplastic materials. 4 Reinforcing polymer matrix with various fillers continues to be one of the most important methods to overcome the shortages of polymer materials, which limit their applications, such as poor mechanical and thermal properties. 5–7 Carbon nanotubes (CNTs) are known as the ideal reinforcing fillers to produce high- performance nanocomposites with excellent mechanical, thermal, and electrical properties 8,9 compared with other fillers such as glass fiber, talc, calcium carbonate, carbon black, and carbon nanofiber. 10 The supreme reinforcing effect of this one- dimensional filler (CNTs) is due to their unique mechanical, elec- trical, and structural properties, that is, very high aspect ratio, typically in the range of several thousand. 11,12 Because of their fine size, high surface energy, and strong intrinsic van der Waals forces, non-functionalized CNTs tend to aggregate, and entangle together spontaneously. 13,14 To overcome high CNT–CNT inter- action as the main factor which hinders the optimal dispersion of CNTs in any polymer matrixes, is still a big challenge. 15,16 Nylon-6/elastomers nanocomposite-TPEs exhibit high modulus, high distortion temperature, high heat resistant, great electrical conductivity, and good barrier properties of gas and water. 17–19 V C 2017 Wiley Periodicals, Inc. J. APPL. POLYM. SCI. 2017, DOI: 10.1002/APP.45977 45977 (1 of 9)