Fabrication of Graphene-Reinforced Nanocomposites with Improved Fracture Toughness in Net Shape for Complex 3D Structures via Digital Light Processing

Abstract

A solvent-free method to fabricate graphene-reinforced nanocomposites in net shape via digital light processing (DLP) 3D printing has been developed in this work. The effect of graphene nanofillers on resin viscosity and wettability for various printing parameters has been examined, with a systematic characterization of the mechanical and thermomechanical properties. With the addition of 0.5 wt.% graphene nanoplatelets in the resin, the flexural modulus and fracture toughness have been improved by 14% and 28% from neat resin, respectively. Thermomechanical properties of graphene-reinforced nanocomposites were also enhanced compared with the neat resin, without scarification in their printability. The feasibility of utilizing the DLP method to fabricate a fracture toughness specimen (KIC test) without complex skill-dependent notch preparation steps was explored, with different notch tip angles printed for net-shaped specimens. This provided a simple and versatile way to perform a quick examination of reinforcing efficiency from nanofillers at very low cost with high resolution and reproducibility. To demonstrate the suitability of current resins for complexly shaped structures, a gyroid scaffold for tissue engineering applications based on current graphene nanocomposite resins has been successfully fabricated via DLP, showing the great potential of current photocurable resins for applications in various fields such as tissue engineering or personalized medical devices without the cost barriers of traditional methods.

A Review on Functionally Graded Materials and Structures via Additive Manufacturing: From Multi‐Scale Design to Versatile Functional Properties

“…Han et al [ 183 ] used SLM technology to prepare titanium/hydroxyapatite (Ti/HA) with quasi‐continuous ratios, in which the ratio of HA varied from 0 to 5 wt% in each functional gradient, providing a wide range of nanohardness (5.11–8.36 GPa) and fracture toughness (3.41–0.88 MPa m 1/2 ), which could be tailored to match those of cortical and cancellous bones. Kawai et al [ 184 ] designed and 3D printed a functionally graded scaffold made of polycaprolactone (PCL) and β‐tricalcium phosphate with spatially controlled porosity, degradation and mechanical strength to reconstruct necrotic bone tissue in the femoral head. It was shown that a combination of FGS scaffolds and bone marrow‐derived mononuclear cells can improve the core decompression outcome in the early stage of osteonecrosis of the femoral head by providing both enhanced biological and biomechanical cues in the osteonecrotic area.…”

Advances in Biodegradable 3D Printed Scaffolds with Carbon-Based Nanomaterials for Bone Regeneration

“…Conversely, DIW, SLA and DLP use liquid raw materials. Ultrasonication is the most common method to achieve the optimal dispersion of nanomaterials in liquid-based raw materials [ 236 , 238 , 239 , 240 ], although other mechanical mixing methods have also been used [ 229 ]. Sometimes, when the viscosity is high, a solvent is added, which promotes dispersion of the nanomaterial [ 237 ].…”

“…G increased the tensile and flexural properties of the matrix. Feng et al [ 240 ] also fabricated DLP samples comprising the same PU resin and 0.5 wt.% GNPs. In this case, the flexural modulus was improved by 14%, while fracture toughness increased by 28%.…”

“… Polylactic acid (PLA)/PUA gyroid scaffolds manufactured by ( a , b ) Stereolithography (SLA) [ 238 ] and ( c , d ) Digital Light Processing (DLP) [ 240 ]. The addition of nanomaterials did not affect the printing process.…”

Additive manufacturing high performance graphene-based composites: A review

“…Compared to conventional processing methods, AM methods may offer GPMCs better mechanical property enhancements as the layer-by-layer fabrication method can align the nanoplatelets. Feng et al [177] fabricated 0.5 wt.% graphene reinforced PU resin using a DLP method. In this case, the flexural modulus and fracture toughness were improved by 14 % and 28 %, respectively, compared to the neat resin.…”