Study of the dielectric heating of graphite oxide and its effect on the microwave‐assisted synthesis of Nylon‐6/graphite oxide polymeric hybrid nanocomposites

Abstract

The present research focuses on the study of the microwave dielectric heating (DH) of graphite oxide (GrO) during the synthesis of Nylon-6/GrO hybrid polymeric nanocomposites (HPNCs) employing different microwave input powers and two GrO morphologies. In this regard, we evaluated GrO powder (GrOP) with dimensions ranging from nanometers to microns and GrO films (GrOF) with millimeter lengths and micron thicknesses. Both morphologies show the same oxidation degree and concentration of functional groups. However, they differ in the number of stacked graphene oxide sheets, thus modify their surface area. The results indicated that the morphology of GrO plays a determining role in its DH behavior in the microwave-assisted polymerization (MAP).On one hand, GrOF contains a high concentration of graphene sheets that induce both an increase in DH and the formation of hot spots. In addition, GrOF has a greater attractive force between its sheets, since its interlamellar space is smaller than 8.4 Å, which makes its exfoliation more difficult. The aforementioned effects significantly reduce the exfoliation and hybridization of GrOF. On the other hand, the larger interlamellar spacing in GrOP weakens the attractive forces compared to GrOF. The lower concentration of graphene oxide lamellae prevents the formation of hot spots, and homogeneously dissipates DH in the reaction medium, maximizing its exfoliation and hybridization. In addition, its behavior presents a defined trend concerning time. These results highlight the importance of considering the GrO morphology in the synthesis of HPNCs as it globally affects the MAPs process, as well as GrO reduction, exfoliation, and hybridization.

Microwave dielectric heating affects the in‐situ polymerization process of Nylon‐6/Ag‐NPs hybrid polymer nanocomposite

“…First, at 50°C, HR increases, which is related to the melting of the ε‐caprolactam monomer 41 . Then, at 200°C, a temperature behavior reduction is observed due to the beginning of polymerization, which consumes part of the monomer and reduces the heat generated 41–43 . Finally, a drastic change in temperature occurred.…”