Characterization and finite element analysis of polylactic acid/polypropylene carbonate (PLA/PPC) for fixation plate in mandibular surgery /
Polylactic acid (PLA) is commonly used in fixation plate for craniomaxillofacial surgery because it has reasonably good tensile strength, biodegradability, and biocompatibility with the human body. However, PLA has very low toughness which limits its use in the screw and fracture fixation plate whic...
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur :
Kulliyyah of Engineering, International Islamic University Malaysia,
2019
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| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
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| Summary: | Polylactic acid (PLA) is commonly used in fixation plate for craniomaxillofacial surgery because it has reasonably good tensile strength, biodegradability, and biocompatibility with the human body. However, PLA has very low toughness which limits its use in the screw and fracture fixation plate which requires plastic deformation during a higher stress level. Polypropylene carbonate (PPC), another biodegradable polymer, has high in elongation at break which could be used to improve the flexibility of PLA for unload bearing application. Therefore, in this project, PPC range between 0 wt% to 30 wt% was chosen to blend with PLA. By using the one-factor design from Design-Expert software, five different compositions of PLA/PPC blends which consist of 100%PLA; 92.5%PLA/7.5%PPC; 85%PLA/15%PPC; 77.5PLA/22.5%PPC; and 70%PLA/30%PPC were produced. This project involved the mechanical, thermal, and chemical characterization followed by finite element analysis (FEA) of PLA/PPC fixation plate on mandibular bone. The tensile test revealed that the elongation at break of the blends increased while its tensile strength decreased as the content of PPC in the blends increased. There was a significant increase of elongation at break from 25.6 % to 185.2 % as the content of PPC in the blends increased from 15 % to 22.5 % which indicates that the toughness of the blends was greatly improved by the addition of PPC. The tensile strength of the blends was significantly lower than that of neat PLA which is produced by low strength and modulus of PPC. The optimization test was conducted and the results revealed nine best solutions of PLA/PPC blends for fixation plate which were above 15 % content of PPC. DSC showed two glass transitions (T_g) with a value of 30℃ for PPC and 54℃ for PLA when 7.5 % of PPC were added. As the amount of PPC increased, T_g of PLA have shifted to a lower temperature and T_g of PPC have shifted to a higher temperature which conclude that PLA/PPC blends were partially miscible. SEM verified some degree of miscibility between the blend components due to the uniform particle size and their homogeneous distribution within the matrix. FTIR illustrate that there is a possible intermolecular interaction between –CH of PLA and –O-C or –O=C of PPC as the wavenumbers of 2998 〖cm〗^(-1) and 2960 〖cm〗^(-1) were shifted to 2990 〖cm〗^(-1) and 2940 〖cm〗^(-1) respectively. Hydrolytic degradation test illustrate that the rate of degradation of the blends decreased as the content of PPC in the blends increased. In-vitro degradation test was conducted and no weight loss observed after three month except for neat PLA which will provide a sufficient time for the bone to heal before the implant degrades. FEA discussed about the Von Misses stress of PLA/PPC fixation plates, the maximum displacement of fractured mandible bone, and the elongation of the fixation plate. The Von Misses stress predicted that all of the blends compositions were safe to be used as a fixation plate since the stress values were less than the yield strength. In addition, the stress value of the fixation plate was gradually decreased up to 20 % when the amount of PPC increased to 30 %. This indicates that the stress shielding effect was successfully reduced. The elongation of the fixation plate was gradually increased from 11.54 μm to 12.55 μm as the amount of PPC in the blends increased from 0 % to 30 % illustrates that the flexibility of the fixation plate was improved by the addition of PPC. Finally, the measured displacement of the fractured gap for all compositions of PLA/PPC blends fixation plate is less than 150 μm which proves the likely success of fracture fixation by using the PLA/PPC blends. |
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| Physical Description: | xix, 97 leaves : colour illustrations ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 86-96). |