Jute yarn with surfaces modified by eco-friendly deposition of carbon nanotubes: mechanical, physical, thermal, and flame-retardant properties

The use of natural fibres has expanded in applications such as polymer composites, automotive components, and the aerospace industry. Among them, jute fibre (JF) stands out because of its commercial availability, low cost, and low density, despite limitations such as its insulating behaviour and flammability. To address these drawbacks, nanoparticles can be deposited via electrophoresis. In this work, carbon nanotubes (CNTs) were deposited onto JF using a modified electrophoretic deposition technique, recently termed High-Impulse Electrophoretic Deposition (HIEPD), which is suitable for aqueous suspensions and insulating materials. This method does not require solvents, enabling a one-pot, eco-friendly approach. The characterisation of JF included the evaluation of mechanical, electrical, thermal, and flammability properties. Optical microscopy confirmed CNT deposition, although aggregates were observed on the fibre surface. Thermogravimetric analysis (TGA) showed an increase in final residue from 4 % (commercial fibre) to 12 % (10 min) and 22 % (20 min), indicating that treatment time affected CNT loading. A reduction in degradation onset temperature suggested catalytic effects associated with CNTs. Electrochemical impedance spectroscopy indicated that conductivity was up to five orders of magnitude higher in fibres treated for 20 min than in untreated fibres. Mechanical tests did not show statistically significant differences, with tensile strengths remaining above 50 MPa. Flame tests indicated improved flame-retardant behaviour, reducing after-flame time from 27 s to 7 s and afterglow time from 8 min to 2 min. The obtained results suggest that CNT deposition onto the JF surface, forming a conductive and protective coating, enhances both the electrical conductivity and flame-retardant performance of the fibres.