Bismuth Polymer Composite for Additive Manufacturing of Flexible Radiation Shielding

The project aims to study the use of bismuth-polymer composite using flexible polymers in additive manufacturing to replace the use of lead as a conventional radiation shielding material in medical applications.

Radiation shields are conventionally made from lead-based materials that are harmful to the human body due to its high toxicity. Lead also has a limitation because of its non-customizable nature due to its manufacturing process. Bismuth (Bi) is a promising alternative to lead due to its similar radiation shielding properties but much lower toxicity. Recent research shows that Bi-polymer composites such as Bi-Polylactic acid (PLA) composite has comparable radiation shielding properties to lead-based radiation shields. The advantage of these materials is that they can be additively manufactured to produce customisable radiation shields. However, Bi-PLA composite is brittle and difficult to be additively manufactured. Hence, this project aims to study the use of flexible polymers such as low-density polyethylene (LDPE) and thermoplastic polyurethane (TPU) to replace PLA as the matrix material. LDPE and/or TPU will be homogeneously mixed in a solution with Bi to produce Bi-polymer composite pellets which will be extruded into filament for additive manufacturing. The additive manufacturing method that will be used is material extrusion. Radiation attenuation tests will be carried out on printed samples to determine the radiation attenuation abilities of the composite using X-rays with energy levels from 50kV to 140kV. Tensile tests will be done to determine the Young’s modulus, the tensile strength, and the elongation at break of the Bi-polymer composite. The properties will be compared with the pure form of the polymer. Thermal properties such as the thermal degradation temperature will be determined using thermogravimetric analysis (TGA), whereas, the melting point and the glass transition temperature will be analysed using differential scanning calorimetry (DSC). The composite produced is expected to possess the same radiation shielding properties as lead-based materials with better printability and mechanical properties compared to Bi-PLA composite.

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