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

## TL;DR

Researchers developed printable biocomposite filaments using hydroxyapatite and graphene in a PLA matrix, optimizing their ratios for mechanical and surface properties.

## Contribution

The first simultaneous modulation of HA and GNP ratios in a PLA matrix for printable composites is introduced.

## Key findings

- HA particles were uniformly dispersed up to the highest HA/GNP ratio.
- Physical adhesion at the HA-PLA interface was observed due to HA porosity.
- Complete exfoliation and dispersion of GNP in the matrix enhanced PLA-GNP synergy.

## Abstract

The proposed strategy for the extrusion of printable composite filaments follows the favourable association of biogenic hydroxyapatite (HA) and graphene nanoplatelets (GNP) as reinforcement materials for a poly(lactic acid) (PLA) matrix. HA particles were chosen in the <40 μm range, while GNP were selected in the micrometric range. During the melt–mixing incorporation into the PLA matrix, both reinforcement ratios were simultaneously modulated for the first time at different increments. Cylindrical composite pellets/test samples were obtained only for the mechanical and wettability behaviour evaluation. The Fourier-transformed infrared spectroscopy depicted two levels of overlapping structures due to the solid molecular bond between all materials. Scanning electron microscopy and surface wettability and mechanical evaluations vouched for the (1) uniform/homogenous dispersion/embedding of HA particles up to the highest HA/GNP ratio, (2) physical adhesion at the HA-PLA interface due to the HA particles’ porosity, (3) HA-GNP bonding, and (4) PLA-GNP synergy based on GNP complete exfoliation and dispersion into the matrix.