Overview

This dissertation, Feasibility Study of Selective Laser Sintering of Biopolymer Scaffolds for Tissue Engineering by Siu-hang, Sherman, Lee, 李兆恆, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract Abstract of thesis entitled Feasibility Study of Selective Laser Sintering of Biopolymer Scaffolds for Tissue Engineering submitted by Lee Siu Hang, Sherman for the degree of Master of Philosophy at the University of Hong Kong in September 2006 The aim of this study was to investigate the feasibility of utilizing selective laser sintering (SLS) to fabricate porous biopolymer scaffolds for bone tissue engineering. The first part of study explored the relationship between the architecture and mechanical properties of the scaffolds. A periodic cell-based design approach (i.e. a unit cell with specific structure is repeated) was adopted TM to create scaffold models. In preliminary trials, DuraForm polyamide (PA) powder was used to construct the scaffolds for architectural analysis, because it helped save material costs and is also commonly used for SLS applications. Scaffolds based on cubic and hexagonal unit cells and with different pore sizes were selected for initial studies, due to their simple geometries and their ease of assembly to form the scaffolds. The theoretical and actual porosities of the scaffolds were determined. The actual porosity of the cubic unit cell scaffolds was found to increase with increasing sintering power, but there were no significant changes for the hexagonal unit cell scaffolds because the loose powder could not be removed from the inner part of the tortuous interconnected pores structure. Compression tests were conducted on the scaffolds with reference to ASTM D695. For a given porosity and sintering power, the cubic unit cell scaffolds showed a higher compressive strength than the hexagonal unit cell counterparts. In addition, finite element analysis (FEA) was carried out to obtain information on stress-strain within the scaffolds. However, the results appeared to be inconsistent with the experimental results. It is believed that the cross sectional area of each individual strut plays an important role in the sintering effect and hence the overall quality of the scaffolds. Although the hexagonal unit cell scaffolds had a larger number of vertical struts to bear the compressive load, their cross sectional area was smaller and which led to a higher heat loss rate and a poorer sintering effect. As a result, they were weaker than the cubic unit cell scaffolds. Attempts were made to produce scaffolds from poly(L-lactide) (PLLA) powder, PLLA being an FDA-approved biopolymer. The first requirement was refinement of raw PLLA powder to microspheres of suitable particle sizes for the SLS process. This was accomplished by using the single emulsion method. PLLA microspheres ranging from about 26 to 40μm were produced. The next requirement involved modification of existing SLS machine to facilitate processing of small quantities of the biopolymer powder. A tailor-made miniature sintering platform, consisting of two powder supply chambers and one build cylinder, was designed, fabricated and installed in the build cylinder of the existing SLS machine. Test runs were performed on the modified machine using PA powder. Slight warpage occurred on the building base of the scaffolds, probably due to a faster heat loss rate when using the miniature sintering platform, but the problem was solved by setting a higher warm-up height for the sintering pro

Full Product Details

9781361480618

Table of Contents

Reviews

Author Information

Tab Content 6

Customer Reviews

Recent Reviews

Countries Available