I have developed graphene (Gr) reinforced Cellulose acetate (CA) film first by dissolving CA in acetone (1.25g CA and 50 ml acetone) followed by dispersing Gr various %s by magnetic stirring. I have also formed the layers of films by gumming with MWCNT-epoxy. I am able achieve surface and volume conductivity. However, the EMI shielding effectiveness (SE) achieved is less than 12dB for two layered film. As per literature more than 20dB is expected. Please let me know the possible reason for achieving weak SE.
#EMI #shileding #effectiveness
Along with the % active material, the thickness of the film is very important. For every frequency band there is a corresponding thickness of coating which is effective. Vary the thickness.
Asit Baran Samui Thank You sir. I varied the thickness, it didn't improve the thickness
In addition to proffesor Baran comment, Graphene tends to agglomerate in non-aqueous media like acetone, especially at higher loadings or without surfactants/functionalization. Add dispersing agents or use functionalized graphene (GO or rGO). Examine dispersion quality with SEM or TEM to identify agglomerates. Conductive fillers like graphene and MWCNTs must form a percolated network within the polymer matrix to ensure efficient shielding. If the network is sparse or disrupted, conductivity might be high enough for basic measurements but insufficient for significant EMI attenuation. Optimize graphene loading: Identify the percolation threshold experimentally. If the graphene used is multilayer or contains a significant proportion of graphite-like particles, its electrical conductivity and specific surface area may be significantly reduced compared to few-layer graphene or monolayer graphene. Use few-layer graphene (FLG) or reduced graphene oxide (rGO) with confirmed high conductivity. Perform Raman spectroscopy to assess defect levels (D/G ratio) and layer thickness (2D peak).
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