Fabrication and characterization of biocomposite scaffold using selective laser sintering

Abstract

Poly (vinyl alcohol) (PVA) is a hydrophilic polymer with potential applications for bone and cartilage repair while hydroxyapatite (HA) resembles closely to the calcified tissue in human bodies. In this work, porous PVA/HA scaffolds were designed using computer aided design (CAD) software and then fabricated via selective laser sintering (SLS). SLS is a rapid prototyping technique which uses CO2 laser to fuse powdered particles together. Selective laser sintering (SLS) was used to sinter this PVA/HA biocomposite at various composition. The microstructure and mechanical properties of the fabricated scaffolds were then assessed.

Thermal extrusion, jar milling and solvent based method were used to fabricate PVA/HA biocomposite. Out of these three preparation methods tested out, only jar milling and solvent based method were suitable to produce PVA/HA biocomposite. Thermal extrusion could not be used to produce PVA/HA biocomposite because PVA has melting point (221˚C) that is too close to its degradation temperature (222˚C). Therefore, thermal extrusion could not be safely performed between the melting point and degradation temperature. Biocomposite produced by the solvent based method and jar milling have similar sintering effect. The maximum amount of HA that could be sintered was 10wt% HA. The chemical structure of PVA/HA remained undisturbed by the preparation process and sintering process as shown by Fourier Transform Infra-Red (FTIR).

Compression testing using jar milled biocomposite revealed that ultimate yield stress, strain and modulus decreases with the addition of HA. However, specimens fabricated with alternating layers of PVA matrix and PVA/HA biocomposite proved to have higher mechanical properties than specimens without alternating layer. Also, angular shape PVA particles were more desirable for sintering than spherical ones due to the increase in contact points between particles.

Therefore, the ability to produce alternating layer scaffolds using SLS with increased mechanical properties have shown potential not only to fabricate PVA/HA composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds.