Polyoxymethylene/Reduced Graphene Oxide-g-Melamine Nano-composites With Low Formaldehyde Emission: Intercalation Structure and Synergistic Thermal Oxidative Stabilization Effect

Formaldehyde emission produced by polymer degradation would cause serious environment pollution. Melamine (MA) as highly efficient formaldehyde scavenger has been widely applied in polyoxymethylene (POM) industry. However, the volatilization, migration and physical loss of MA during processing and application have become a serious problem for POM production. In this work, MA was first grafted onto graphene oxide (GO) surface through amidation reaction, and reduced graphene oxide-g-melamine (rGO-MA) hybrid was prepared by subsequent reduction. The POM/rGO-MA nano-composite was then manufactured via conventional melt processing. By incorporation of MA, hydrogen bonding was enhanced for composite, and POM molecules were intercalated into reduced graphene oxide (rGO) layers effectively with high intercalation ratio, while rGO was exfoliated and uniformly distributed in POM matrix. Compared with neat POM, the formaldehyde emission amount (FEA) of POM/rGO-MA decreased notably by 50.8%, and the thermal degradation temperature and degradation activation energy (E-a) were improved significantly. Meanwhile, the retention of mechanical property of POM/rGO-MA remained stable, while melt index increased much slowly during thermo-oxygen aging process. By grafting MA onto rGO surface, both the thermal migration resistance of MA and radical scavenging ability of GO were enhanced, while rGO-MA exhibited excellent synergistic removal effect of formaldehyde generated by POM degradation. Besides, the composite showed extraordinary oxygen barrier property, and thermal oxidation degradation of POM was delayed effectively. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a reduced graphene oxide-melamine hybrid was prepared by grafting melamine onto the surface of graphene oxide and subsequent reduction. The hybrid was then used to manufacture a polyoxymethylene/reduced graphene oxide-melamine (POM/rGO-MA) nanocomposite. The incorporation of melamine improved the hydrogen bonding and intercalation of POM molecules in the composite, resulting in a significant decrease in formaldehyde emission and improved thermal degradation properties. The mechanical property of the composite remained stable, and the melt index increased slowly during thermo-oxygen aging. The grafting of melamine onto the graphene oxide surface enhanced the thermal migration resistance of melamine and radical scavenging ability of graphene oxide, leading to an excellent synergistic removal effect of formaldehyde and remarkable oxygen barrier property.