Preparation and structure–property regulation of seed-type hemp-based regenerated cellulose filaments in a LiCl/DMAc solvent system

To achieve high-value utilization of seed-type hemp bast fiber, this study investigated the dissolution and rheological behavior of degummed hemp bast fiber in a LiCl/DMAc solvent system, as well as the effects of coagulation bath temperature and water bath draw ratio on the structure and properties of regenerated cellulose filaments prepared via pilot-scale wet spinning. Within the investigated process window, the optimal cellulose concentration for spinning was identified at 3.5%, at which the spinning solution exhibited a moderate structural viscosity index (Δη) with good flowability and spinnability. When coagulated at 35 ℃, the fiber crystallinity index reached 59.63%, and the dry tensile strength increased to 3.53 cN/dtex, representing a 16.5% improvement compared with fibers prepared at 20 ℃. At a water bath draw ratio of 1.5, the sonic velocity orientation factor exceeded 0.95, and the dry tensile strength increased to 2.59 cN/dtex, which was 24.5% higher than that of the undrawn fibers. The results indicate that coagulation bath temperature primarily affects fiber crystallinity through thermodynamic processes, whereas drawing mainly promotes molecular chain orientation via kinetic processes, accompanied by a partial reduction in crystallinity. This study demonstrates the feasibility of preparing regenerated cellulose filaments from seed-type hemp bast fiber under controlled laboratory and pilot-scale conditions, and offers insights into filament formation and structural control. • Continuous regenerated cellulose filaments were wet-spun from seed-type hemp using LiCl/DMAc. • A 3.5 wt% cellulose solution ensured homogeneous dissolution, stable rheology, and spinnability. • Coagulation temperature and water-bath drawing governed crystallinity and orientation via thermodynamic and kinetic effects. • Regenerated filaments with tensile strength up to ∼3.5 cN/dtex were obtained from hemp bast by-products.