Improving the mechanical behavior of reduced graphene oxide/hydroxyapatite nanocomposites using gas injection into powders synthesis autoclave

Abstract

in this study, we show the synthesis of reduced graphene oxide/hydroxyapatite (rGo/HA) composites using a hydrothermal autoclave with argon-15% hydrogen gas injection. This both increases the hydrothermal pressure and uses hydrogen as a reductive agent in the process. The synthesized powders were then consolidated with spark plasma sintering method. The analysis of the consolidated samples included Vickers Indentation technique and cell viability. The results showed that injected gases in the autoclave produced powders with a higher crystallinity compared to synthesis without the gases. Also, hydrogen gas led to increased reduction of GO. The microscopic analysis confirmed existing graphene sheets with folding and wrinkling in the powders and indicated that various preferential directions played a role in the growth of hydroxyapatite crystals. The results showed that in general, graphene sheets increased the mechanical properties of HA. In the samples synthesized with injected gases, this increase was more significant. Interface analysis results indicate that reduced graphene oxide (rGO)/HA interface is likely coherent. These nanocomposites were biocompatible and showed some hydrophobicity compared to pure HA.

Characterization of hydroxyapatite-reduced graphene oxide nanocomposites consolidated via high frequency induction heat sintering method

“…However, it should be noted that the MTT assay is one of the most common experiments in biocompatibility assays but it is not complete enough and more in vitro and in vivo assays are required to prove the biocompatibility. It can be seen ( Figure 10(b,c)) that the surface of the samples from the hydrophilic (in pure HA [52]) state was somewhat close to the hydrophobic (in HA-rGO nanocomposites) state (very similar results to this analysis have been published elsewhere with clearer images [68]). The reason for this is that GO is hydrophilic and is somewhat hydrophobic after reduction.…”

Ambient temperature sulfonated carbon fiber reinforced PEEK with hydroxyapatite and reduced graphene oxide hydroxyapatite composite coating

“…46 The differences in the water contact angle value after the application of the coatings can be attributed to the high hydrophilicity of HA as compared to RGO, discussed in literature. 47 Proper interaction and attachment of cells unto the surface of an implant is key to their successful clinical application. 48 As seen in the cytocompatibility results, all sam- showed they adhered in a shape of spindle with filopodia extensions.…”

Study of mechanical performance of polymer nanocomposites reinforced with exfoliated graphite of different mesh sizes using micro-indentation

“…The plastic energy as a quantitative reflection of the viscosity effect is due to the internal friction inside the polymer/composite. 36,37 The plastic properties of ExG/ Epoxy826 nanocomposites continue to increase until the ExG concentration reaches 16 wt%. Besides, as shown in Figure 15(b), an abnormal reduction phenomenon was observed for the 16 wt% ExG/ Epoxy826 nanocomposite, which was attributed to the apparent agglomeration of EXG in the nanocomposite.…”