Investigation of the mechaniological behavior of bio-support systems

Permanent implantable bio-support systems are commonly used in the treatment of disorders occurring in different tissues. Such implant materials are removed from the body through a secondary surgical intervention after the healing process is completed. This situation may negatively affect patient comfort and lead to additional costs. Therefore, the use of biodegradable products has recently gained prominence in medical applications. However, the major challenge associated with these materials is that biodegradation does not occur synchronously with the healing process. In order to achieve synchronization during the regeneration process, the biodegradation behavior under physiological conditions must be investigated in detail. Within the scope of this thesis, PLA/PCL polymer blends capable of degrading under physiological conditions, as well as PLA/PCL/CNCs nanocomposites, were produced and their properties were comprehensively examined in different sections of the study. In the first part of the thesis, PLA/PCL blends were obtained by incorporating PCL into the PLA matrix at weight ratios of 10% and 20%. Nanocomposite filaments were then produced by reinforcing the polymer blends at fixed weight ratios (9:1 and 8:2 PLA:PCL) with 5 wt% CNCs. The properties of the resulting filaments were characterized and compared with those of neat PLA filaments. The results showed that all produced filaments were within the diameter range suitable for FDM applications (1.75±0.05 mm). TGA analyses indicated that all filaments maintained thermal stability up to approximately 256 °C, and that filaments containing CNCs exhibited higher thermal stability. In the final part of this section, auxetic sheets were fabricated using optimized three-dimensional printing parameters based on MFI, TGA, and DSC data, and good dimensional stability was achieved. In the second part of the thesis, representative volume elements (RVEs) were modeled to estimate the elastic constants of the materials, and the suitability of the tissue scaffolds for bone tissue applications was discussed from a biomechanical perspective. The modeled RVEs were observed to be in good agreement with experimental results. The elastic modulus values of tissue scaffolds produced with different porosity ratios were found to be suitable for bone tissue applications. In the final part of the thesis, the degradation behaviors of the tissue scaffolds that were determined to be biomechanically suitable were examined in detail. Degradation studies were conducted under both loaded and unloaded conditions using in vitro experiments that simulated physiological conditions. The results revealed that nanocomposite-based tissue scaffolds exhibited higher water absorption capacity and, consequently, higher degradation rates.