Effect of MWCNT content on thermal and shape memory properties of epoxy nanocomposites as material for morphing wing skin M. H. Mat Yazik 1 • M. T. H. Sultan 1,2,3 • Ain U. M. Shah 1,2 • M. Norkhairunnisa 1,2 Received: 29 June 2018 / Accepted: 8 May 2019 Ó Akade ´miai Kiado ´, Budapest, Hungary 2019 Abstract In the present study, a shape memory epoxy polymer (SMEP) system was prepared from commercially available EPON 826 and NGDE, and then, 0.5%, 1.0% and 1.5% mass percentage of multi-walled carbon nanotubes (MWCNTs) were incorporated into it so as to prepare nanocomposites. The inclusion of the nanofiller into the SMEP system was expected to enhance its properties. Then, experimental analyses were conducted to study the effect of incorporating different amounts of MWCNTs on the thermal properties of the obtained nanocomposites, namely dynamic mechanical analysis, thermo- gravimetric analysis (TGA) and shape memory cyclic testing. It was found that the increasing content of MWCNTs in the SMEP system decreased the glass transition temperature of the developed nanocomposites (SMEPCs). TGA results indicated that the incorporation of MWCNTs into the SMEP decreased its thermal stability. The authors explained these results by the lack of interaction between the MWCNTs and the epoxy matrix. In consideration of the use of the SMEP for morphing applications, the increment in MWCNT content was found to improve the shape recovery properties of the SMEP. Thus, the study demonstrates that the incorporation of a MWCNT nanofiller can help enhance the properties of the SMEP system and overcome its limitations, revealing the high potential of the developed shape memory composite materials to be used for various industrial applications. Keywords Carbon nanotubes Á Nanofillers Á Shape memory epoxy Á Composites Á Morphing Introduction The shape memory effect is the ability of a material to exhibit shape memory when reacting towards an external stimulus. Shape memory materials (SMMs) can be classi- fied into three types, namely shape memory alloy (SMA), shape memory ceramic (SMC) and shape memory polymer (SMP). Each type has a different shape memory enabler, which endows the material with the shape memory ability. In the SMA, the martensitic–austenitic phase transforma- tion enables the shape memory properties. On the other hand, the SMP realizes the shape memory ability by the dual-domain mechanism (a hard domain and a soft one), representing both the glassy and rubbery states of the shape memory polymer. Meanwhile, for the SMC, the underlying mechanism can be either phase transformation, similar to SMA, or the dual-domain mechanism as in SMP. Research on shape memory polymers can be traced back to 1940, when L.B. Vernon claimed that a dental material (methacrylic acid ester resin) had an ‘elastic memory’ property [1]. Interestingly, the patent was recorded even before the invention of the shape memory alloy [2]. However, the research on shape memory polymers did not receive much attention until 1960, when the polyethylene tube and film were invented [3, 4]. Regardless of the early history of the SMP, research results on the SMA and SMC are currently widely used in the industry, while the SMP remained alien to the scientific community until recently, & M. T. H. Sultan thariq@upm.edu.my 1 Department of Aerospace Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia 2 Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia 3 Aerospace Malaysia Innovation Centre (944751-A), Prime Minister’s Department, MIGHT Partnership Hub, Jalan Impact, 63000 Cyberaya, Selangor Darul Ehsan, Malaysia 123 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-019-08367-6