Multifunctional UV-curable carbon nanofiber coatings on hemp/viscose nonwovens: electrostatic dissipation, thermal stability, and electromagnetic shielding behavior

Natural fiber-reinforced composites are widely studied as sustainable alternatives to synthetic materials due to their lightweight and renewable nature. In this study, a hemp/viscose spunlace nonwoven was coated with a UV-curable elastomeric resin containing carbon nanofibers (CNF) and acid-activated carbon nanofibers (ACNF) at 0.75, 1.5, and 3 wt%. Acid activation introduced oxygen-containing functional groups, improving nanofiller dispersion and interfacial adhesion. The composites were characterized by FTIR, RAMAN, TGA, XRD, contact angle, surface resistivity, and EMI shielding effectiveness (SE) analyses. Microscopy confirmed successful nanofiller incorporation, particularly in ACNF-modified samples. Surface resistivity results showed a concentration-dependent decrease in resistivity, indicating a shift toward electrostatic dissipative behavior. ACNF samples exhibited lower resistivity than untreated CNF systems. Thermal analysis revealed enhanced thermal stability and higher char residue in reinforced composites. Although measurable attenuation was observed, the SE values (<5 dB) indicate that a fully developed conductive network was not established within the investigated filler range. These findings suggest that the current formulations primarily provide electrostatic dissipation rather than effective electromagnetic shielding. Overall, UV-curable CNF/ACNF coatings improved surface functionality and thermal performance, but low filler contents limited electromagnetic shielding efficiency.