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<p>Nanocomposites comprising polylactic acid (PLA), a biodegradable polymer, and graphene (0.5–10 wt%) were prepared through a solvent-based approach to examine the transition from a liquid-like state to a solid-like state as well as the percolation threshold. The characterization of viscoelastic properties, electrical conductivity, and graphene dispersion was conducted utilizing an oscillatory rheometer, direct current electrical measurements, and atomic force microscopy (AFM). The rheological assessments demonstrated an enhancement in both storage (G’) and loss (G’’) moduli in comparison to unmodified PLA, accompanied by a reduced frequency dependence at lower frequencies, signifying a transition to elastic behaviour at 4.4 wt% (2.5 vol%)—the rheological percolation threshold. Electrical percolation was detected at 5.9 wt% (3.4 vol%), with conductivity exhibiting a sharp increase from 10⁻¹¹ to 10⁻³ S/m in the range of 4–6 wt%. AFM analyses verified the uniform dispersion of graphene (thickness of 4.5&#xa0;nm, diameter approximately 150&#xa0;nm, aspect ratio roughly 33), whereas the excluded volume methodology estimated the percolation threshold to be at 3 wt% (1.7 vol%). The discrepancies in percolation thresholds arise from differences in inter-particle spacing, with electrical conduction necessitating closer contacts (5&#xa0;nm) compared to the rheological networking (~ tens of nm). These insights contribute to the advancement of sustainable, conductive nanocomposites intended for biomedical applications, such as shape-memory devices.</p>

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Unveiling network evolution in PLA/Graphene bio-nanocomposites: multi-Scale analysis

  • 期刊论文

  • 发表日期：

    2025年11月11日

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  • Soheila Lashgari,
  • Elham Aram,
  • Somayeh Lashgari,
  • Mohsen Ahi

摘要

Nanocomposites comprising polylactic acid (PLA), a biodegradable polymer, and graphene (0.5–10 wt%) were prepared through a solvent-based approach to examine the transition from a liquid-like state to a solid-like state as well as the percolation threshold. The characterization of viscoelastic properties, electrical conductivity, and graphene dispersion was conducted utilizing an oscillatory rheometer, direct current electrical measurements, and atomic force microscopy (AFM). The rheological assessments demonstrated an enhancement in both storage (G’) and loss (G’’) moduli in comparison to unmodified PLA, accompanied by a reduced frequency dependence at lower frequencies, signifying a transition to elastic behaviour at 4.4 wt% (2.5 vol%)—the rheological percolation threshold. Electrical percolation was detected at 5.9 wt% (3.4 vol%), with conductivity exhibiting a sharp increase from 10⁻¹¹ to 10⁻³ S/m in the range of 4–6 wt%. AFM analyses verified the uniform dispersion of graphene (thickness of 4.5 nm, diameter approximately 150 nm, aspect ratio roughly 33), whereas the excluded volume methodology estimated the percolation threshold to be at 3 wt% (1.7 vol%). The discrepancies in percolation thresholds arise from differences in inter-particle spacing, with electrical conduction necessitating closer contacts (5 nm) compared to the rheological networking (~ tens of nm). These insights contribute to the advancement of sustainable, conductive nanocomposites intended for biomedical applications, such as shape-memory devices.