Effect of Amine Molecular Chain Length on the Mechanical and Thermal Properties of Functionalized Graphene Oxide/Polyurea Nanocomposites

Abstract

To improve the overall performance of polyurea, linear diamines with three different chain lengths (1,2-ethylenediamine (EDA) and amino-terminated polyoxypropylenes D230 and D2000) were reacted with graphene oxide (GO) by reaction of amines with carboxyl groups, and three different amino-functionalized graphene oxide (AGO) nanosheets (EDA-GO, D230-GO and D2000-GO) were prepared. Subsequently, an AGO flake was bonded to a polyurea (PUA) substrate by an in situ chemical process. Analytical tests, including X-ray photoelectron spectroscopy (XPS), showed that diamines were attached to the GO flake. The reinforcement properties of the nanocomposites were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile testing. AGO nanosheets, especially EDA-GO, result in a certain degree of enhancement in the thermal and mechanical properties of nanocomposites formed with polyurea. The TGA and DSC results indicated that the T5% and Tg of the nanocomposites at low AGO loading were increased compared with those of pure polyurea. Meanwhile, the elongation at break of the nanocomposite film with 0.1 wt% EDA-GO loading was 240% higher than that of pure polyurea, and tensile strength was increased by 80% over that of pure polyurea. We provide a new approach to the chemical conversion of GO/PUA nanocomposites by preparing AGO and complexing it with polyurea.