摘要
Cellulose dissolution in N-methylmorpholine N-oxide (NMMO) remains challenged by strong hydrogen bonding, high crystallinity, and limited solvent accessibility, necessitating effective pretreatments for efficient lyocell fiber production. We introduce an integrated approach combining NaOH-induced hydrogen-bond weakening with cryogenic ball milling fragmentation to enhance macromolecular disentanglement in cellulose dissolution for the lyocell process. A multiscale characterization suite i.e. FTIR, XRD, BET, and SEM was used to confirm that the combined treatment synergistically reduced crystallinity from 86.2% to 63.8%, increased specific surface area by ∼26%, and generated a defibrillated, porous morphology. Centrifugal NMMO-retention method showed that this structural evolution significantly enhanced swelling capacity, with the NaOH and cryogenic milling combined cellulose treatment achieving a 56% higher solvent retention than native pulp in 70 wt% NMMO. Moreover, centrifugal retention profiles classified solvent as free, trapped, and bound, with combined treatment maximizing bound NMMO for optimal disentanglement. In addition, polarized optical microscopy demonstrated a reduction in dissolution time, from 50 min for native pulp to just about 20 min for the synergistically pretreated cellulose. UV-visible spectroscopy of the dope extracts further confirmed that the combined pretreatment minimizes NMMO degradation during dissolution, as evidenced by consistently lower absorbance values for the combined treatment across all wavelengths and time points (0, 24, and 72 h), indicating fewer chromophoric degradation products and superior dope quality. By linking molecular-scale activation with mechanical fragmentation, this synergistic strategy offers a sustainable and potentially energy-efficient pathway for cellulose processing, with promising applications in nanocellulose and bio-based composites.
危险品化学品经营许可证（带存储）