Reactive copolymer functionalized graphene sheet for enhanced mechanical and thermal properties of epoxy composites

Abstract

Uniform dispersion of graphene nanosheets (GNS) in a polymer matrix with strong filler–matrix interfacial interaction, preserving intrinsic material properties of GNS, is the critical factor for application of GNS in polymer composites. In this work, a novel reactive copolymer VCz–GMA containing carbazole and epoxide group was designed, synthesized and employed to noncovalently functionalize GNS for preparing epoxy nanocomposites with enhanced mechanical properties. The presence of carbazole groups in VCz–GMA enables the tight absorption of copolymer on to graphene surface via π–π stacking interaction, as evidenced by Raman and fluorescence spectroscopy, whereas the epoxide segments chemically reacts with the epoxy matrix, improving the compatibility and interaction of graphene with epoxy matrix. As a result, the VCz–GMA–GNS/epoxy composite showed a remarkable enhancement in both mechanical and thermal property than either the pure epoxy or the graphene/epoxy composites. The incorporation of 0.35 wt % VCz–GMA–GNS yields a tensile strength of 55.72 MPa and elongation at break of 3.45, which are 42 and 191% higher than the value of pure epoxy, respectively. Increased glass transition temperature and thermal stability of the epoxy composites were also observed. In addition, a significant enhancement in thermal conductivity was achieved with only 1 wt % VCz–GMA–GNS loading. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2776–2785

Bio-Based Hyperbranched Toughener From Tannic Acid and Its Enhanced Solvent-Free Epoxy Resin with High Performance

“…NMR is a powerful tool to characterize the chemical structure of samples. As shown in the 1 H-NMR and 13 C-NMR spectra of AA, MPA, TA, and CATA ( Figs. 4 and 5), the 1 H-NMR spectrum of MPA and the corresponding proton assignments are shown in Fig.…”

“…However, the high crosslinking density of epoxy resins leads to inadequate toughness, thus limiting its use in applications requiring good impact strength [10]. Various materials such as clay [11], rubber, nanomaterial [12,13], hyperbranched polymers [11], and engineering plastic particles have been introduced into epoxy materials to improve mechanical properties, especially impact strength and tensile strength [2]. But the key point for these methods is to toughen epoxy resin without sacrificing mechanical strength and thermal properties [2].…”

Noncovalent functionalization of carbon nanotube using poly(vinylcarbazole)‐based compatibilizer for reinforcement and conductivity improvement in epoxy composite

“…Recently, epoxy composites with different nanomaterials (e.g., CNTs, graphene, clay, and nanoparticles) have demonstrated highly improved toughness, stiffness strength, and even multifunctional properties. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] So, combining modified CNTs with epoxy resin is gaining great interest for the development of new functional composite materials.…”

“…However, its highly cross‐linked structure of epoxy resin suffers from inherent brittle nature and poor crack resistance. Recently, epoxy composites with different nanomaterials (e.g., CNTs, graphene, clay, and nanoparticles) have demonstrated highly improved toughness, stiffness strength, and even multifunctional properties . So, combining modified CNTs with epoxy resin is gaining great interest for the development of new functional composite materials.…”

Dichlorobenzene: an effective solvent for epoxy/graphene nanocomposites preparation

“…By using DMF, a lot of works reported enhancements in the final properties of epoxy/graphene nanocomposites. Other solvents like tetrahydrofuran [ 21 – 24 ], acetone [ 25 – 28 ], dichloromethane [ 29 – 32 ], isopropyl alcohol [ 33 , 34 ], water [ 35 – 39 ], etc. have also been reported in the processing of epoxy/graphene nanocomposites.…”