IMPROVED STABILITY OF GRAPHENE OXIDE-SILICA NANOHYBRIDS AND RELATED POLYMER-BASED NANOCOMPOSITES

Abstract

Although its promising properties make the graphene oxide (GO) very interesting as filler for polymer matrices, some problems related to its thermal stability in the region which ranges from 80 to 200 °C, are crucial for the possibility to melt process GO together with practically all the polymers [1,2]. Moreover, above 100 °C GO lamellae were found to become stacked. In this work, two different ways to preserve the GO structure and ensure its dispersion within different polymer matrices have been investigated and schematized in Fig. 1. Exfoliation plays a key-role in the achievement of good mechanical properties since it preserves the GO from both stacking phenomena. The capability of silica to exfoliate the GO lamellae is confirmed by SEM analysis and probably this feature leads to the achievement of a better morphology in terms of exfoliation/intercalation thus resulting in a better load transfer. Moreover, the presence of silica results in an increased thermal stability of the GO, as confirmed by Raman analysis and TGA. The nanocomposites prepared by incorporating GO-silica nanohybrids within PA6, EVA and PC showed mechanical properties higher than those directly melt mixed with GO. Furthermore, the GO-silica-polymer nanocomposites were found to have mechanical performance similar or better than GO-polymer prepared via solvent casting.