Eco-Friendly Produced Lightweight Structural Graphene/ Polyamide 12 Nanocomposite: Mechanical Performance and the Controlling Microstructural Mechanisms Marwa Adel, 1 Ossama El-Shazly, 2 El-Wahidy F. El-Wahidy, 2 Azza El-Maghraby, 1 Marwa A.A. Mohamed 1 1 Fabrication Technology Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA City), New Borg El-Arab, Alexandria 21934, Egypt 2 Physics Department, Faculty of Science, Alexandria University, Alexandria, Egypt The present study explores the potential use of graphene nanoplatelets (GL-GNPs), synthesized from glucose through a new chemical approach that is facile, economical, and eco- friendly alternative to the conventional Hummer’s method, as a nanoreinforcement in polymers for the production of light- weight structural polymer nanocomposites. Understanding the interface character of GL-GNPs/Polyamide 12 (PA12) nanocomposites with various nanofiller loadings and how this affects their tensile behavior, are focal points of interest. Results reveal that enhancements in polymer stiffness and strength are superior at low GL-GNPs content than higher contents. This is attributed to higher degree of GL-GNPs exfoliation and increased polymer phase crystallinity. Inter- estingly, abundant small/imperfect PA12 crystallites have grown on the GL-GNPs surface, strongly interlinking thus the polymer and graphene phases within nanocomposites. The intensity of such crystallites in interface region is the determi- nant of the nanocomposites’ Young’s modulus, assessed at small applied tensile stress. While the GL-GNPs-PA12 interfa- cial bonding is the determinant of yield and ultimate strengths, estimated at medium and high stress levels. Over- all, the 1 wt% GL-GNPs/PA12 nanocomposite is considered the optimum. Its low density and good mechanical perfor- mance among the previously developed graphene/Polyamide nanocomposites, propose promising future for GL-GNPs- based nanocomposites as ecofriendly and cost-effective lightweight structural material. POLYM. ENG. SCI., 00:000–000, 2017. V C 2017 Society of Plastics Engineers INTRODUCTION Polymer nanocomposites (PNCs) are defined as polymeric- based materials filled with inclusions, having at least one dimen- sion less than 100 nm. In contrast to the micro-scale fillers, incor- poration of nanofillers into polymers can result in substantial property enhancements beyond those of traditional polymers, at relatively low nanofiller loadings. This is due to the unique intrin- sic properties of nanomaterials and their high surface to volume ratio which enables strong interactions with polymer matrices. Thus, the advantage of PNCs is to provide value-added properties to the polymer without sacrificing its processability, elasticity, and light weight [1–3]. Accordingly, in recent decades PNCs have gained tremendous industrial interest. The potential engineering applications range from solar cells and electromagnetic interfer- ence shielding to drug delivery and bone replacements [4, 5]. In particular, PNCs are leading candidate structural materials when the structure light weight is a matter of concern in addition to rigidity, such as in aerospace, maritime, automotive, defense, and wind energy industries [6, 7]. Transportation vehicle light weight- ing is an important worldwide demand for fuel conservation [8]. Conversely, wind turbine blades should be as light as possible to maximize the electrical power harvesting from the wind energy [9, 10]. For this purpose, various types of nanofillers including sil- icates, clay, cellulose nanocrystals, and carbon-based nanomateri- als such as carbon black, exfoliated graphite, carbon nanotubes, carbon nanofibers, graphene oxide (GO), and graphene have been used to fabricate PNCs [6]. Among these materials, graphene is the most promising material due its intriguing properties including extraordinary mechanical properties with Young’s modulus of 1 TPa and ultimate strength of 130 GPa, extremely light weight (0.77 mg/m 2 ) and large specific surface area (2,600 m 2 /g), very high electrical conductivity (6,000 S cm 21 ), and exceptional ther- mal conductivity (5,000 Wm 21 K 21 ) [11, 12]. The bulk properties of graphene/PNCs is mainly dictated by the structural characteristics of graphene that control its intrinsic properties [7] and the interfacial interactions between graphene nanosheets and polymer matrix [13]. Stronger interfacial interac- tions between graphene and polymer matrix can be usually achieved by improving the dispersion and distribution of gra- phene nanosheets in the polymer matrix, integrating graphene nanosheets with larger aspect ratio within the polymer matrix [14] and enhancing covalent or non-covalent bonding at the filler-matrix interface through chemical modification of the gra- phene nanosheets and/or the polymer matrix [6, 7, 13–15]. Con- versely, the graphene synthesis strategy strongly affects its structural characteristics [7, 16]. Various methods have been regularly used for graphene synthesis, including micromechani- cal cleavage of graphite [12], epitaxial growth on SiC [17], chemical vapor deposition [18], and chemical exfoliation of graphite [19, 20]. The first three techniques can produce high quality graphene with excellent physical properties. However, they are limited by their low production yield. Thus, with these approaches, it is difficult to obtain a high graphene yield to sat- isfy the need as composite fillers [7]. At present, the most viable route to produce graphene in considerable quantities is the chemical exfoliation of graphite. The process is often proceeded through two approaches; (i) oxidation of graphite into graphite oxide, followed by exfoliation into GO and finally chemical or thermal reduction to graphene [19, 21, 22] or (ii) intercalation Correspondence to: M.A.A. Mohamed; e-mail: mmohamed@srtacity.sci.eg and marwa945@yahoo.com Contract grant sponsor: City of Scientific Research and Technological Appli- cations (SRTA City). Additional Supporting Information may be found in the online version of this article. DOI 10.1002/pen.24683 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2017 Society of Plastics Engineers POLYMER ENGINEERING AND SCIENCE—2017