Graphene/Nanohydroxyapatite hybrid reinforced polylactic acid nanocomposite for load-bearing applications

Biocompatible Composite Filaments Printable by Fused Deposition Modelling Technique: Selection of Tuning Parameters by Influence of Biogenic Hydroxyapatite and Graphene Nanoplatelets Ratios

“…The biogenic facet was also followed in this study based on the facile and reproducible synthesis of hydroxyapatite (HA) from natural resources (e.g., bovine or fish bones [ 26 , 27 , 28 , 29 ], marble, or seashells [ 23 , 30 , 31 ]) due to its physico-chemical and biological affinity for and similarity to natural bone [ 6 , 27 , 30 , 32 ]. Nonetheless, structures composed of HA alone revealed unsuitable mechanical resistance and a slow degradation rate with minimum induced porosity over prolonged periods from implantation [ 1 , 33 , 34 ].…”

“…For creating advanced composite filaments, recent biomedical studies have exploited the beneficial interplay between PLA and synthetic spherical HA particles, acquired mainly through chemical surface modification (the addition of binders and/or impact modifiers), but not always with the expected outcomes [ 18 , 34 , 35 , 36 , 37 ]. In addition to the limited incorporation ratios of ceramic material, ranging from 3 to a maximum of 40 wt.%, the reported composites lacked a proper particle distribution in the polymeric matrix, which led to the formation of agglomeration sites [ 6 , 38 , 39 ], as well as the ability to preserve the filaments’ surface uniformity and constant diameter size [ 18 , 38 ], both mandatory requirements for printable materials [ 40 , 41 , 42 ].…”

“…Other engineering strategies for the development of composite filaments target the graphene family of materials due to their promising mechanical and biocompatible features, which are transferable to graphene-reinforced mixtures [ 12 , 14 , 34 , 43 ]. Graphene nanosheets/nanoplatelets (GNP) can be securely anchored and bonded to matrix particles as nano-reinforcements, allowing for continuous stress transmission during the deformation process [ 3 , 19 ].…”

“…Graphene nanosheets/nanoplatelets (GNP) can be securely anchored and bonded to matrix particles as nano-reinforcements, allowing for continuous stress transmission during the deformation process [ 3 , 19 ]. However, graphene exfoliation, filler–matrix adhesion, dispersion, and orientation remain current problems given the predisposition of GNP to layer stacking and agglomeration [ 12 , 34 ]. While some studies have shown that graphene-reinforced PLA poses poor mechanical properties, others have reported that by changing the raster orientation or using larger nanoplatelets, its capabilities may be improved [ 2 ].…”

“…While some studies have shown that graphene-reinforced PLA poses poor mechanical properties, others have reported that by changing the raster orientation or using larger nanoplatelets, its capabilities may be improved [ 2 ]. Similarly, researchers have investigated the benefits of integrating essential oils or chemically prepared agents for enhancing the dispersion degree for both PLA/GNP [ 12 , 44 ] and PLA/GNP/HA mixtures [ 34 ]. These studies reported that even though the proportion of GNP was reduced to 1–4 wt.% for PLA/GNP and to 0.01–0.1 wt.% for the PLA/GNP/HA samples, the improvements in the mechanical behaviour were signalled only at the lowest amounts of GNP, in opposition to what was expected.…”