Sodium Alginate/Graphene Nanoplatelet Nanocomposites: Effect of Crosslinker and Graphene Nanoplatelet Loading

Abstract

In this article, the effect of crosslinker and filler loading on the properties of sodium alginate/graphene nanoplatelet (SA/GNP) nanocomposites is investigated. The nanocomposites samples were prepared using the solvent casting method. Swelling tests were performed to measure the degree of swelling. It was found that the degree of swelling increased with a longer immersion time in the 0.2M concentration of CaCl2. Interestingly, only a 12-minute immersion time in the 0.8M concentration of CaCl2 resulted in the lowest degree of swelling, which was 93.69%. Analysis of the gel fraction showed an increase in gel content at higher CaCl2 concentrations. To crosslink the SA/GNP nanocomposites, a concentration of 0.8 M CaCl2 and an immersion time of 12 minutes were selected. When the mechanical properties of SA with different CaCl2 concentrations were investigated, it was found that SA crosslinked at the 0.8M concentration had a higher elastic modulus than the 0.2M concentration of CaCl2, which was probably due to the higher crosslinking density. The mechanical properties of SA/GNP nanocomposites were found to decrease with decreasing GNP loading, which can be attributed to the presence of GNP. In addition, higher GNP loading resulted in improved electrical conductivity of the SA/GNP nanocomposites. X-ray diffraction (XRD) analysis proved that the crystallinity of SA increased with longer immersion times and the addition of GNP. Fourier transform infrared spectroscopy (FTIR) showed no significant changes in the peak characteristics of SA when the concentration of CaCl2, immersion time and GNP loading increased.