Browsing by Author "Square, Lynndle"

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    Comparative analysis of single-walled, double-walled, and multi-walled carbon nanotube-reinforced Poly(2,5-benzimidazole) composites: Enhanced structural and thermal stability for radiation shielding in low Earth Orbit
    (Elsevier, 2025-03-05) Square, Lynndle; Oryema, Bosco; Mafoko, Pako; Ellis, Ernst; Vorster, Henriette
    Poly(2,5-benzimidazole) (ABPBI) composites reinforced with 1 wt% single-wall (SWCNT), double-wall (DWCNT), and multi-wall (MWCNT) carbon nanotubes were synthesised and evaluated for radiation shielding applications in Low Earth Orbit (LEO). The structural and thermal properties of these nanocomposites were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Atomic Force Microscopy (AFM). FTIR analysis confirmed the retention of ABPBI's characteristic molecular structure across all nanocomposites, with ABPBI/DWCNT exhibiting the strongest molecular bonding. Thermal analysis demonstrated exceptional stability, with ∼95% weight retention at 400 °C and ∼70% at 900 °C, suggesting suitability for high-temperature applications. To assess radiation resistance, 3 MeV He2+ ion bombardment was performed on ABPBI/DWCNT nanocomposites. Post-irradiation FTIR and XRD results indicated mild molecular degradation but preserved semi-crystalline structures, demonstrating strong radiation tolerance. AFM analysis further revealed nanoscale surface modifications, providing insights into radiation-induced morphological changes and confirming the structural resilience of ABPBI-based nanocomposites. The results suggest that ABPBI/DWCNT exhibits promising mechanical integrity, thermal stability, and radiation resistance for space applications.
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    Radiation-induced degradation in the properties of pristine anddouble-walled carbon nanotube-enhancedpoly (2,5-benzimidazole) polymers for radiation shielding in the LEO
    (Elsevier, 2025-09-01) Oryema, Bosco; Square, Lynndle; Ellis, Ernst
    Degradation in the properties of polymer-based materials in space environments is a critical challenge for developing lightweight radiation shielding solutions. In this paper, a comparative study of the impacts of helium ion (He+) irradiation one of the ion species in the Low Earth Orbit (LEO) environment on the structural and optical properties of pristine and 1.0 wt% double-walled carbon nanotube (DWCNT)-enhanced poly(2,5-benzimidazole) (ABPBI) polymers for LEO radiation shielding applications was conducted. The two polymer categories were separately chemically prepared in the laboratory, moulded, dried, and cut into 1 cm × 1 cm pieces, and bombarded with 0.35 MeV He+ ions at varying fluences. The Ultraviolet–Visible-Near-Infrared (UV–Vis-NIR) optical analyses of the polymers following the ion bombardment revealed that He+ irradiation considerably raises the Urbach energy and decreases the optical bandgap, indicating a rise in electronic defects and structural disorder. On the other hand, the Fourier Transform Infrared (FTIR), Atomic Force Microscopy (AFM), and X-ray Diffraction (XRD) analyses revealed higher levels of structural degradation in the pristine ABPBI samples, suggesting changes brought about by irradiation-induced oxidation and chain scission processes. In contrast, the 1.0 wt% DWCNT-ABPBI composite demonstrated improved optical and structural integrity, retention, and resistance to He+ ion-induced damage. According to the results, 1.0 wt% DWCNT reinforcement reduces radiation-induced deterioration and offers more protection from energetic ion exposure in the LEO settings. Thus, this work highlights the distinct impact of He+ ion interactions with ABPBI and the effectiveness of DWCNT inclusion in improving polymer resilience, and it contributes to the fundamental understanding of the polymer composite for radiation shielding applications.