Enhancement of thermal and mechanical performances of epoxy nanocomposite materials based on graphene oxide grafted by liquid crystalline monomer with Schiff base

Liquid crystal (LC) monomer with Schiff base-grafted functionalized GO (M2-g-GO) sheets was successfully prepared to enhance the dispersion and interfacial interaction between additives (M2-g-GO) and the epoxy matrix (E-51), resulting in the enhancement of thermal and mechanical performances of epoxy nanocomposites. The structures and performances of neat epoxy, GO/epoxy nanocomposite, and M2-g-GO/epoxy nanocomposites were characterized by a few analytical tests, such as Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, dynamic mechanical analyzer, differential scanning calorimetry, and thermogravimetric analysis. Meanwhile, the polarized optical microscope test displayed LC monomer with Schiff base-grafted GO has been successfully synthesized. The T_g and thermal performance of M2-g-GO/epoxy nanocomposites were distinctly promoted compared with those of the neat epoxy and GO/epoxy nanocomposite. Meanwhile, mechanical tests demonstrate the M2-g-GO/epoxy nanocomposites possess greater impact strength, flexural strength, and flexural modulus than those of the neat epoxy and GO/epoxy nanocomposite. It is also worth mentioning that the flexural strength with the adding content of 3 wt% increased by 62.1%, and the flexural modulus with the adding content of 3 wt% increased by 19.1%. Moreover, T_d1% of M2-g-GO/epoxy nanocomposites were all higher than the neat epoxy (170 °C), and the T_d5% of epoxy composites were around 385 °C, which were nearly 15 °C higher than that of neat epoxy. Meanwhile, the char yield of M2-g-GO/epoxy nanocomposites at 650 °C is 1.4% higher than that of 3 wt% GO/epoxy nanocomposites. Hence, the M2-g-GO exhibits predominant feasibility as effective increased thermal and toughness additives for leading to the enhancement of thermal and mechanical performances of nanocomposites.