Nitrogen plasma effect on the structural, thermal, and dynamic mechanical properties of PVA/starch/graphene oxide nanocomposite

In this paper, polyvinyl alcohol/starch/graphene oxide nanocomposites containing glycerol were prepared via the solution-casting technique. The effect of different times (10, 20, 30, and 40 min) of nitrogen plasma irradiation on the structural, thermal, and dynamic mechanical properties of nanocomposites was studied. The dominancy of the chain scission process over crosslinking after irradiation for 10 min compared to the crosslinking at higher exposure times specifically at 30 min was proven by XRD. Also, field emission scanning electron microscopy confirmed these findings, where the most improved interface compatibility in nanocomposites shown after irradiation for 30 min. Thermogravimetric analysis indicated that after irradiation, the lowest thermal stability in nanocomposites shown in the sample irradiated for 10 min, while the highest thermal stability was shown in the sample irradiated for 30 min. It was found that the dynamic mechanical properties of nanocomposites were dependent on exposure time. The maximum storage modulus value was achieved after 30 min compared to the lowest value obtained after 10 min. Also, the calculated crosslinking density was increased by 49.8% after nanocomposite irradiation for 30 min compared to the unirradiated sample. Furthermore, the effect of plasma irradiation on both storage modulus and loss modulus of nanocomposites and their dependencies on temperature and frequency were studied.