Development of new highly efficient ionizing radiation protection systems

Samanta dos Santos Godinho

Key information

Authors:

Samanta dos Santos Godinho (Samanta dos Santos Godinho)

Supervisors:

Ana Maria de Matos Charas (Ana Maria de Matos Charas); António Cândido Lampreia Pereira Gonçalves (António Cândido Lampreia Pereira Gonçalves)

Published in

June 26, 2026

Abstract

This thesis investigates the development of new, highly efficient, and flexible polymer-based composites for ionizing radiation protection, aiming to overcome the toxicity and weight limitations of traditional lead-based systems. High-atomic-number (high-Z) fillers, specifically Bismuth Telluride (Bi₂Te₃) and Bismuth-Antimony (Bi-Sb) solid solutions, were incorporated into a Polydimethylsiloxane (PDMS) matrix. The research focuses on addressing manufacturing challenges such as particle sedimentation and agglomeration. A dual-processing strategy was developed, combining high-energy ball milling (BM) to refine particle size and suppress anisotropic morphologies with a layered casting technique to ensure uniform filler distribution. Morphological characterization via SEM confirmed that BM produces finer, more isotropic fragments, significantly improving suspension stability and packing efficiency. Radiological tests demonstrated that ball-milled powders achieved a mass efficiency increase of approximately 4 to 4.5 times compared to manually ground samples. Specifically, Bi₂Te₃ layered configurations reached a mass efficiency factor of 0.088%/mg. The results show that bismuth-based systems can achieve a 17% weight reduction compared to lead shielding while maintaining comparable effective atomic numbers (Zₑff ≈ 60.5 for Bi-Sb). The Bi-Sb system proved to be a robust and scalable alternative, while Bi₂Te₃ demonstrated superior mass efficiency for weight-critical applications. This work establishes a reliable fabrication route for low-toxicity, lightweight, and flexible radiation barriers suitable for medical, industrial, and aerospace environments.