Graphene oxide as multi-functional initiator and effective molecular reinforcement in PVP/epoxy composites

• Published in: Journal of molecular structure 2021-04, Vol.1230, p.129873, Article 129873
• Main Authors: Jayan, Jitha S., Pal, Kaushik, Saritha, Appukuttan, Deeraj, B.D.S., Joseph, Kuruvilla
• Format: Article
• Language: English
• Subjects: Epoxy; Grafting from; Graphene oxide; Initiator; Polymerization; Toughening
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2021.129873

•Polymer is grafted onto the surface of GO by following “grafting from” technique.•The grafted filler is characterized by different analytical and morphological studies.•The grafted filler is incorporated in epoxy and analysed the mechanical, thermal and rheological properties.•The grafted filler showed an enhanced toughness without compensating other inherent properties of epoxy. In this work, grafting of Polyvinylpyrrolidone (PVP) onto the surface of Graphene Oxide (GO) by following the ‘grafting from’ technique was carried out by the GO-initiated cationic polymerization of N-Vinylpyrrolidone monomers. The successful grafting of PVP onto GO sheets was confirmed with the help of various techniques like FTIR, XRD, Raman and XPS. The PVP polymer chain grafted GO (GO-g-PVP) was incorporated into the epoxy matrix as a reinforcement in order to investigate the effect in thermo-mechanical properties of epoxy. From static mechanical testing, it was observed that neat PVP adversely affects the mechanical (tensile) strength of epoxy, whereas the GO-g-PVP shows an improvement of about ~13% when compared to the virgin epoxy composites. Rheological data reveals the transformation of epoxy resin from the Newtonian behavior to shear thickening nature by the incorporation of GO-g-PVP. Dynamic mechanical analysis and the intensity of tan δ curves also ratify the rheological observation. The fracture toughness of epoxy composites showed a significant improvement of about 190% than the neat epoxy composites. Electron microscopes are employed to observe the Fractograms to systematically analyze the toughening mechanisms involved. Thermal stability and the temperature of glass transitions were optimized by TGA and DSC analysis. [Display omitted]