A green method to prepare nanosilica modified graphene oxide to inhibit nanoparticles re-aggregation during melt processing

Abstract

A graphene oxide-silica nanohybrid (GOS), self-assembled into a lasagna-like structure, was prepared in water and used as a filler for the melt preparation of polyamide 6 (PA6)-based nanocomposites. For sake of comparison, PA6-based materials were prepared under the same processing conditions by adding GO only or a physical mixture of GO and silica (GO+S). All the materials were characterized from a morphological, spectroscopic, thermal, dynamic-mechanical (DMA) and mechanical point of view. For all the nanocomposites, the interphase was studied either by analyzing loss factor plots coming from DMA measurements and by implementing a novel approach, i.e. combining solvent extraction, SEM and EDX measurements. While GO and GO+S showed an almost negligible effect on the macroscopic features of PA6, due to lack of dispersion, PA6-GOS ternary nanocomposites displayed an outstanding enhancement of mechanical and thermo-mechanical performance. This feature is likely due to the formation of an extended and strong interphase. In fact, the silica layers intercalated between GO lamellae played as an exfoliating agent, thus proving to be particularly efficient in avoiding self-aggregation of GO sheets, while those covalently attached to basal planes of GO acted as a rivet, capable to interlock the surrounding polymer chains. Finally, with respect to other techniques commonly adopted for the fabrication of polymer-graphene nanocomposites, the green route herein proposed does not involve any toxic solvent nor time-consuming protocols, and allows achieving remarkable improvements in stiffening (up to +180%), strengthening (up to +210%) and toughening (up to +210%) at extremely low filler contents (0.25% or 0.5%).

Role of nitrogen–oxygen plasma functionalization of carbon nanotubes in epoxy nanocomposites

“…That band's intensity varies with the system's aromaticity degree and the plasmon p-p* peak's intensity, between approximately 291-294 eV. The band at approximately 285.2 eV is attributed to the C-H bond from the aliphatic structure, related to hexagonal lattice defects (sp 3 [29]. From the XPS spectra, it can also be concluded that the highest percentage of C-O groups was achieved by CNT/O sample ($14% against $7% of pristine CNT) and for O-C 5 O groups was achieved by CNT/40 sample ($4.6% against $1.9% of pristine CNT), indicating that the plasma treatment at 40 W promotes the highest increase in oxygen functional groups.…”

“…Besides, the CNTs' characteristic chemical inertia impairs the adhesion to the matrix and therefore, a good tension transfers . The interfacial interaction between the matrix and the nanoparticles, which is indicated by an interphase region , can be improved with chemical or physical functionalization . The chemical functionalization, which consists of inserting functional groups onto the surface of nanoparticles, can be done through a plasma process.…”

Polymer Composites Reinforced with Natural Fibers and Nanocellulose in the Automotive Industry: A Short Review

“…However, increased durability of these materials has raised strong concerns about the large accumulation of plastic waste in the environment [12]. Thus, the development of cleaner processes associated with the interest in environmentally friendly materials has been the focus of research around the world [13][14][15][16][17]. In this context, the addition of natural fillers (natural fibers, cellulose nanocrystals, and nanofibrillated cellulose) in the polymers has been a way to prepare ecofriendly composites with improved properties, minimizing the problem in relation to the residue accumulation [18][19][20][21].…”

Synthesis and evaluation of high‐temperature properties of butylated graphene oxide composite incorporated SBS (C4H9‐GO/SBS)‐modified asphalt

“…PointProbe Plus Silicon‐SPM‐probes were used with Al backside reflex coating, at a resonance frequency of ≈300 kHz and tip apical diameter of ≈10 nm. All the scans were executed at room temperature under N 2 atmosphere …”