Effect of exfoliation medium on the morphology of multi-layer graphene oxide and its importance for Poly(Ethylene terephthalate) based nanocomposites

Author(s)

Pinto, Gabriel M. ^[1] ; Silva, Giovanna da C. ^[1] ; Fechine, Guilhermino J. M. ^[1]

Affiliation

^[1] Univ Prebiteriana Mackenzie, Mackenzie Inst Res Graphene & Nanotechnol MackGra, Rua Consolacao 896, BR-01302907 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Polymer Testing; v. 90, OCT 2020.
• Web of Science Citations: 1

Abstract

Poly(ethylene terephthalate) (PET)/multi-layer graphene oxide (mGO) nanocomposites were produced using the melt compounding technique, with the aid of a twin-screw extruder. The main goal was to investigate the effect of different exfoliation media on the morphology of graphene oxide and its effects, mainly on the mechanical performance of PET/mGO based polymer nanocomposites. Two different exfoliation media (water and ethanol) were used for the mGO synthesis. Based on each medium, nanocomposites with three different mGO contents (0.05 wt%, 0.1 wt%, and 0.3 wt%) were produced. When exfoliated in water, mGO sheets present larger lateral dimensions, i.e., higher surface area available to interact with polymer chains. All nanocomposites presented similar crystallinity, but with a slight increase related to the neat PET, indicating the nucleating effect of mGO. A theoretical model was used to predict the nanocomposites elastic modulus, justifying the experimental results. The biggest mechanical improvement was presented by a composite with low content of water-exfoliated mGO (0.1 wt%). The polymer tensile strength, strain at break, and toughness were improved by 19%, 238% and 590%, respectively. A significant reduction in the polymer dissipation factor (Milo) with mGO content was also verified, indicating some confinement of polymeric chains due to interactions with the mGO sheets. The different surface fracture mechanisms presented by the nanocomposite with 0.1 wt% water-exfoliated mGO were verified, in which a good interface allowed greater release of strain energy. The XR-MT data confirmed that differences in mGO morphology can sensitively affect the final composite properties, characterising it as the driving force for mechanical improvements. Therefore, a melt compounded PET/graphene derivative composite is presented, exhibiting more promising results than what is already reported by solution mixed and in-situ polymerised composites. It was possible due to the strategic processing route utilised, in which the exfoliated mGO was premixed with the polymer powder using the SSD technique. (AU)

• FAPESP's process: 18/18055-0 - Investigation of the barriers properties of PET/GO nanocomposites for the packaging industry
• Grantee: Giovanna da Cruz Silva
• Support type: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 18/10910-8 - Photodegradation and photostabilization of polymer nanocomposites based on two-dimensional fillers
• Grantee: Guilhermino José Macêdo Fechine
• Support type: Regular Research Grants
• FAPESP's process: 18/05440-2 - Mechanical and barrier properties of polymer nanocomposites based on poly(ethyelene terephthalate) - PET and graphene oxide-GO
• Grantee: Gabriel Matheus Pinto
• Support type: Scholarships in Brazil - Master
• FAPESP's process: 12/50259-8 - Graphene: photonics and opto-electronics: UPM-NUS collaboration
• Grantee: Antonio Helio de Castro Neto
• Support type: Research Projects - SPEC Program