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Rapid advancements in wireless communications and smart devices have intensified electromagnetic interference, creating an urgent demand for lightweight, efficient shielding materials. Hybrid graphene and multi-walled carbon nanotube (MWCNT) nanostructures offer ideal properties due to high electrical conductivity, low density, and flexibility. This work evaluates the S-band (2.65 – 3.90 GHz) shielding performance of poly(methyl methacrylate) (PMMA) composites reinforced with e-beam irradiated hybrid carbon nanostructures. Five formulations with varying filler loadings (15 wt% AH, 20 wt% AM1), thicknesses (0.208 – 0.48 mm), and irradiation doses (50 – 400 kGy) were characterized. Thermal analysis (TGA/DSC) demonstrated improved thermal stability and restricted chain mobility at 400 kGy. Electrical conductivity increased from 2.3 × 10-13 S/m (neat PMMA) to 0.0902 S/m. SEM imaging showed graphene exfoliation at high doses, alongside internal nanopores (250–290 nm) that lowered shielding performance. Vector Network Analyzer measurements confirmed an absorption-dominant mechanism, with absorption (SEA) accounting for 82 – 87% of total shielding effectiveness (SET) and negligible multiple reflections (SEM). The PMMA/AM1 composite (20 wt% filler, 0.48 mm, 50 kGy) achieved the highest performance, reaching an average SET of 10.13 dB (peak 11 – 14 dB) compared to <1 dB for pure PMMA. In the 15 wt% series, the 50 kGy sample (0.28 mm) yielded the highest SET (7.75 dB). Moderate e-beam irradiation combined with increased thickness and filler loading provides an effective route for optimizing flexible EMI shielding components for sub-6 GHz 5G applications.
| Conference Topics | Nanomaterials and Nanotechnology |
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