Double-Layered Tin-Polydimethylsiloxane (PDMS) Composites: Evaluation of Porosity and Structural Morphology of Polymeric Composites

The pursuit of advanced materials for radiation protection has highlighted the potential of polymer–metal composites. Porosity is a key factor influencing radiation attenuation, as fewer voids reduce pathways for radiation penetration. Recent studies emphasize the role of filler distribution in enhancing both mechanical properties and shielding performance. This work investigates the structural morphology and porosity of tin–PDMS composites prepared with pure tin (PS) and tin alloy (AS) fillers at 10–60 wt.% loadings, along with a tin–alloy mixture series (TM). Morphological features, particle distribution, oxygen content, and porosity were comprehensively analyzed. Results show that porosity strongly correlates with filler distribution and composition. The AS5 composite (50 wt.% tin alloy) exhibited the most balanced properties, achieving a low porosity of 0.34% with satisfactory density and microstructural stability. Within the TM series, TM6 (60 wt.% tin mixture) demonstrated promising features for high-density shielding applications due to its high tin content with a density of 5.32 g/cm3 and porosity less than 2.0% of the nominal acceptance threshold for the composite. These findings establish the foundational microstructural characteristics of tin–PDMS composites as a step toward developing lead-free radiation shielding materials.