Three Dimensional Morphology and Compressive Behaviour of Sintered Biodegradable Composite Scaffolds
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1097-GG06-07
Three Dimensional Morphology and Compressive Behaviour of Sintered Biodegradable Composite Scaffolds Elaheh Ghassemieh Mechanical Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom ABSTRACT Porous poly-L-lactide acid (PLA) scaffolds are prepared using polymer sintering and porogen leaching method. Different weight fractions of the Hydroxyapatite (HA) are added to the PLA to control the acidity and degradation rate. The three dimensional morphology and surface porosity are tested using micro CT, optical microscopy and scanning electron microscopy (SEM). Results indicate that the surface porosity does not change by addition of HA. The micro Ct examinations show slight decrease in the pore size and increase in wall thickness accompanied with reduced anisotropy for the scaffolds containing HA. SEM micrographs show detectable interconnected pores for the scaffold with pure PLA. Addition of the HA results in agglomeration of the HA which blocks some of the pores. Compression tests of the scaffold identify three stages in the stressstrain curve. The addition of HA adversely affects the modulus of the scaffold at the first stage, but this was reversed for the second and third stages of the compression. The results of these tests are compared with the cellular material model. The manufactured scaffold have acceptable properties for a scaffold, however improvement to the mixing of the phases of PLA and HA is required to achieve better integrity of the composite scaffolds. INTRODUCTION Bioresorbable scaffolds of polylactic acid (PLA) offer several benefits. They require only a single surgery and leave native tissue behind. They gradually transfer load to tissue during the degradation period, allowing for bone remodelling and reducing the risk of re-fracture. They also can be used to deliver drugs, growth factors or other substances conducive to the healing of bone locally to the implant site.1 Several manufacturing processes are tried and tested for producing scaffolds of biodegradable polymers. In this research we manufacture scaffolds of PLA with HA as reinforcement phase through sintering solvent free process. The strength and structure of the final scaffolds are sensitive to the sintering time in the novel sintering process. The time must be sufficient to allow bonding between polymer particles but not too long as to allow the polymer to fully surround the porogen particles and cause a closed pore structure. The use of pressure and heating in the process creates a dense structure and hence care must be taken in ensuring complete removal of the porogen. The removal of the salt particles is normally achieved by leaching the composites in distilled water. The advantages of the method used are simplicity, lack of presence of solvent and high porosity and strength. The produced scaffolds are characterised for their morphology and mechanical response under compressive load and their degradation rate. The degradation results are not reported here to keep the article within the lim
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