Structural reinforcement and failure analysis in composite nanofibers of graphene oxide and gelatin

Abstract

In this work we study the mechanical properties and failure mechanism of nanocomposites made of graphene oxide sheets embedded in polymeric systems, namely films and electro-spun nanofibers. In this last system, contrary to conventional bulk composites, the size of the nano-reinforcement (GO sheets) is comparable to the size of the nanofibers to be reinforced (≈ 200 nm). As an ideal polymeric matrix we use gelatin.We demonstrate that the high chemical affinity of the two materials hinders the renaturation of gelatin into collagen and causes a nearly ideal mixing in the GO-gelatin composite. Adding just 1% of GO we obtain an increase of Young's modulus >50% and an increase of fracture stress >60%. We use numerical simulations to study the failure mechanism of the fibers. Calculations agree very well with experimental data and show that, even if cracks start at GO sheet edges due to stress concentrations, crack propagation is hindered by the nonlinear behaviour of the matrix. As an additional advantage, the presence of the GO sheets in continuous gelatin films improves the material stability to phosphate buffer solutions from 2 days to 2 weeks, making it a better material than gelatin for applications in biological environments.4

Encapsulation of Holy Basil Essential Oil in Gelatin: Effects of Palmitic Acid in Carboxymethyl Cellulose Emulsion Coating on Antioxidant and Antimicrobial Activities

“…The XRD pattern of the stored UC became narrower in comparison with the freshly dried UC, showing the increase in the extent of the triple helix content of gelatin (more renaturation) (Bigi et al 2004;Panzavolta et al 2014). In accordance with the results obtained from our previous study (Sutaphanit and Chitaprasert 2014), the gelatin renaturation process promoted the expulsion of the encapsulated HBEO from the gelatin matrices to the microcapsule surfaces due to the reduction of the space available for the encapsulated HBEO.…”

Graphene Oxide/Polymer‐Based Biomaterials

“…Gelatin is used in tissue engineering, drug delivery, and gene therapy and as a vascular prosthesis and wound dressing. [100] However, it is moisture sensitive, with poor mechanical properties, including a low toughness. Therefore, it is used with reinforcement fillers or non-covalent/covalent crosslinking although residual crosslinking agents could lead to toxic side effects.…”

“…[1,6,100] Jalaja et al [1] and Nagarajan et al [6] crosslinked gelatin with dextran aldehyde and gluteraldehyde, respectively. More than 0.5 wt% of GO in gelatin led to the agglomeration of GO.…”

Nanoscale Mechanics of Graphene and Graphene Oxide in Composites: A Scientific and Technological Perspective

“…[5,19,48] 3) Chemistry -a fine control of the surface chemistry of the nanosheets will be required to tune the density and nature of chemical defects, to maximize the interaction between the sheets and the polymer matrix and hence ensure uniform dispersion in the composite and efficient stress transfer between the different phases of the composite material with moderate intrinsic flake strength reduction.…”