Crystallization behavior, thermal property and enzymatic degradation of PVP/amylose in the presence of graphene oxide nanosheets

The PVP/amylose composite films with different amounts of graphene oxide (GO) were prepared by means of a solution casting method. The solution of PVP/amylose/GO was exposed to ultrasonic irradiation (10, 30, 50, and 70 W) and then prepared for casting. The crystallization behavior, thermal stability and enzymatic degradation of PVP/amylose were investigated with differential scanning calorimetry (DSC), X-Ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR spectroscopy. XRD patterns monitored that the addition of GO induced a layered structure to the PVP/amylose composite films. This result indicated that GO nanosheets were uniformly dispersed into the composite network. The thermal properties measured by DSC showed that the glass transition temperature (Tg) was shifted to a lower temperature with the humidity percent increasing. DSC thermograms for PVP/amylose/GO showed an endothermic reaction and reduction in peak temperature, revealing that GO increased the thermal stability of PVP/amylose composite films. FTIR analysis suggests that PVP/amylose composites become more resilient to enzymatic attacks as the content of GO reaches higher, being related to the reduction of Amylose-Amylose interactions in the presence of GO nanosheets. These results indicate that this approach is an efficient method to improve the properties of PVP/amylose.