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<p>This study reports the functionalization of recycled polyethylene terephthalate (RPET) with lanthanum oxide (La<sub>2</sub>O<sub>3</sub>) nanoparticles at loadings of 1, 2, 4, and 8 wt.% to enhance its physicochemical, optical, dielectric, and thermal properties for advanced material applications. Molecular electrostatic potential (MESP) analysis revealed enhanced charge redistribution and increased electronegativity with La<sub>2</sub>O<sub>3</sub> incorporation, indicating improved chemical reactivity and potential in energy storage systems. X-ray diffraction (XRD) confirmed a transition from amorphous to semi-crystalline structures, maximized at 4 wt.% La<sub>2</sub>O<sub>3</sub>, while FT-IR spectra displayed characteristic peak shifts and bond formations evidencing strong RPET-La<sub>2</sub>O<sub>3</sub> interactions. Optical studies revealed a marked increase in the UV-region absorption coefficient (α) with increasing La<sub>2</sub>O<sub>3</sub> content, indicating enhanced photon-polymer interactions, while maintaining high transparency in the visible region. The direct optical band gap decreased from 3.98&#xa0;eV (pristine RPET) to 3.77&#xa0;eV at 8 wt.% loading, confirming matrix-filler interaction and tunability of optical properties. Dielectric analysis showed significant improvements in dielectric constant (ε′), dielectric loss (ε″), and AC conductivity (σ<sub>AC</sub>), with the 4 wt.% composite exhibiting the highest σ<sub>AC</sub> (1.12 × 10<sup>–5</sup> S·cm<sup>−1</sup> at 100&#xa0;°C) and stable dielectric performance over a broad frequency range. Thermal analysis (TGA and DSC) confirmed enhanced thermal stability, with the 4 wt.% sample exhibiting a 12&#xa0;°C increase in onset decomposition temperature and altered melting profiles, indicating strong interfacial bonding and the formation of thermally resistant phases. These findings identify 4 wt.% La<sub>2</sub>O<sub>3</sub> as the optimal loading, offering a balanced improvement in optical absorption, dielectric stability, conductivity, and thermal resistance, thereby establishing La<sub>2</sub>O<sub>3</sub>-RPET nanocomposites as promising candidates for UV-shielding, dielectric, and thermally stable conductive materials for electronic and energy applications.</p>

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Tailoring bandgap and dielectric properties of RPET using lanthanum oxide nanofillers for UV-shielding and optoelectronic applications

  • 期刊论文

  • 发表日期：

    2025年9月29日

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  • Amr Antar,
  • Mahmoud M. Maghawry,
  • Medhat A. Ibrahim,
  • Ahmed I. Ali,
  • Nasser Ayoub,
  • Dongwhi Choi,
  • Galal H. Ramzy

摘要

This study reports the functionalization of recycled polyethylene terephthalate (RPET) with lanthanum oxide (La2O3) nanoparticles at loadings of 1, 2, 4, and 8 wt.% to enhance its physicochemical, optical, dielectric, and thermal properties for advanced material applications. Molecular electrostatic potential (MESP) analysis revealed enhanced charge redistribution and increased electronegativity with La2O3 incorporation, indicating improved chemical reactivity and potential in energy storage systems. X-ray diffraction (XRD) confirmed a transition from amorphous to semi-crystalline structures, maximized at 4 wt.% La2O3, while FT-IR spectra displayed characteristic peak shifts and bond formations evidencing strong RPET-La2O3 interactions. Optical studies revealed a marked increase in the UV-region absorption coefficient (α) with increasing La2O3 content, indicating enhanced photon-polymer interactions, while maintaining high transparency in the visible region. The direct optical band gap decreased from 3.98 eV (pristine RPET) to 3.77 eV at 8 wt.% loading, confirming matrix-filler interaction and tunability of optical properties. Dielectric analysis showed significant improvements in dielectric constant (ε′), dielectric loss (ε″), and AC conductivity (σAC), with the 4 wt.% composite exhibiting the highest σAC (1.12 × 10–5 S·cm−1 at 100 °C) and stable dielectric performance over a broad frequency range. Thermal analysis (TGA and DSC) confirmed enhanced thermal stability, with the 4 wt.% sample exhibiting a 12 °C increase in onset decomposition temperature and altered melting profiles, indicating strong interfacial bonding and the formation of thermally resistant phases. These findings identify 4 wt.% La2O3 as the optimal loading, offering a balanced improvement in optical absorption, dielectric stability, conductivity, and thermal resistance, thereby establishing La2O3-RPET nanocomposites as promising candidates for UV-shielding, dielectric, and thermally stable conductive materials for electronic and energy applications.