Mechanical Properties of Fully Recyclable 3D-Printable Materials Used for Application in Patient-Specific Devices in Radiotherapy.

The exponential growth of plastic production in the healthcare sector and the limited capacity of conventional recycling systems have created a global environmental challenge. Latest 3D printing technologies have the potential to solve this problem by enabling on-demand, localized manufacturing. This study aimed to investigate the mechanical properties of 3D-printed ABS composites with BiO fillers after multiple recycling and irradiation cycles to assess their suitability for creating robust, reusable supporting devices for radiotherapy. Filaments of PLA, ABS, and ABS composites enriched with 5 wt% and 10 wt% BiO were extruded, repeatedly recycled through shredding and re-extrusion up to ten times and irradiated to 70 Gy using a 6 MeV photon beam to simulate clinical radiotherapy conditions. In contrast to PLA, ABS demonstrated better recyclability; however, after ten recycling cycles, its tensile strength declined from 25.1 MPa to 20.9 MPa, and its Young's modulus decreased from 2503.5 MPa to 1410.4 MPa. Incorporation of 5 wt% BiO into ABS significantly improved recyclability and mechanical retention. After ten recycling rounds, an ABS composite containing 5 wt% BiO retained tensile strength of 22.2 MPa, modulus of 1553.9 MPa, and strain at break of 14.4%. In contrast, the composite enforced with 10 wt% BiO showed slightly lower performance, likely due to filler agglomeration. Under irradiation, the ABS-5 wt% BiO composite exhibited minimal additional degradation, maintaining mechanical integrity superior to other materials. These results indicate that ABS-5 wt% BiO is a promising, recyclable material for durable, patient-specific devices in radiotherapy, supporting sustainability in medical manufacturing.