Enhanced Mechanical Properties of Polyhydroxyamide/Graphene Nanosheets Nanocomposites

In this study, we prepared a series of polyhydroxyamide (PHA) nanocomposites containing graphene nanosheets (GNS) using solution-mixing and systematically investigated their morphology, structures, and mechanical properties as functions of the GNS content. As an effective reinforcing material for the nanocomposites, the GNS used in this study was applied by introducing a general acid treatment and rapid thermal expansion of natural graphite (NG), and was characterized as disordered with a diameter of tens of nanometers after ultrasonic dispersion treatment was applied for the solution-mixing. In addition, the morphological features and X-ray analysis clearly show that the GNS was dispersed homogeneously within the PHA matrix without the formation of any aggregates and generated a suitable network structure for the nanocomposites. As a result, the tensile mechanical properties of PHA/GNS nanocomposites increased noticeably with the increase in the GNS content as compared with PHA nanocomposites containing pristine NG. In particular, the tensile strength and initial modulus of a PHA/GNS nanocomposite film containing 2.0 wt% GNS were 110.7 MPa and 3.25 GPa, which are increases of 83 % and 150 % compared with a neat PHA film, respectively. In addition, the rate of increase in the initial modulus of this study shows much higher results than those of our previous studies on various PHA nanocomposites including multi-walled carbon nanotubes and/or clay nanoparticles as reinforcing materials, and it can be interpreted that the GNS applied in this study plays an optimal role in enhancing the physical properties of the PHA.