Enhanced Mechanical Strength and Controlled Biodegradability of Bio-Membranes Synthesized from Waste Hemp Fibers

In this work, agricultural hemp waste was converted into cationically modified membranes through a two-step procedure. First, the post-harvest hemp fibers underwent delignification, after which they were quaternized using a Deep Eutectic Solvent (DES) composed of chlorocholine chloride and urea. The cationized fibers were then pressed and cross-linked with citric acid (CA), a natural cross-linker, to obtain membrane sheets. The untreated fibers (NtHF) and the resulting membranes were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Mechanical performance was evaluated by measuring the breaking force and determining the tensile strength using the Brazilian test. Biodegradation was monitored for 90 days in a controlled soil-burial environment at 24 °C, comparing membranes made from untreated versus cationized hemp fibers. The modified material exhibited a notable increase in tensile strength (2.41 MPa), attributed to the combined effects of enhanced intermolecular interactions within the cationic hemp matrix and the stronger cross-linking provided by citric acid. Signs of biodegradation appeared after just 14 days, with approximately 25% mass loss. In contrast, the untreated fibers degraded slightly faster, underscoring the stabilizing effect of citric acid.