An ETS research team led by Lucas Hof and Nicole Demarquette, in collaboration with CHUM research teams, carried out mechanical tests to test the recyclability potential of plastics used in oncology. Discover the summary of their work.
Summary
Technology has revolutionized personalized oncology treatments with 3D-printing using biodegradable PLA (Polylactic acid) in modern medicine. The use of 3D printed PLA parts, though suitable for personalized medical parts, presents challenges in oncology due to single-patient use requirements. Thus, after serving their purpose, irradiated PLA’s recyclability must be assessed for use in future treatments.
Within that scope, we assessed material degradation using FTIR (Fourier transform infrared spectroscopy) and MFI (Melt flow index) tests to examine chemical and rheological changes in recycled PLA, after multiple recycling cycles and taking into account the potential effect of irradiation treatment. Additionally, CT scans were used to study how degradation affects material electron density, a crucial factor for its suitability in oncology treatments.
From FTIR analysis of unirradiated samples, we observed an increase in the intensity of bands at 2850 and 2920 cm-1 as a function of recycling. These bands indicate how much of PLA’s structure is in a crystalline form. When PLA is recycled, its macromolecules may break due to heat and shear forces. The shorter chains can more easily fold into an organized crystalline structure, showing up as more intense bands in FTIR. Regarding MFI, it increases linearly with the recycling step. This increase as a function of recycling confirms that the material is going through chain scission after each cycle, as shorter chains flow more easily than longer chains. With what concerns irradiated material, only one recycling step was performed up until now. However, it is notable that the bands at 2850 and 2920 cm-1 increase in intensity in a much stronger manner than for the unirradiated material after only one recycling step, suggesting that after only a single step, the material is already crystallizing much more than the unirradiated one. From the MFI value obtained for the 1st cycle in the irradiated material, it is confirmed that the radiation exposure facilitates the chain breakage in the recycling process, as the MFI value was already much closer to the 2nd cycle than to the 1st one of the unirradiated material.
