Composite Fibers of Hydroxypropyl Cellulose and Alginate Spun From Aqueous Solution: Crosslinking Effects on Water Absorption and Mechanical Properties

ABSTRACT Alginate‐based composite fibers were fabricated by dissolving sodium alginate (Algn, 0.5–3.0 wt%) and hydroxypropyl cellulose (HPC, 2.0 wt%) in water, followed by extrusion into a CaCl 2 coagulation bath (10 or 100 mM). The immediate gelation formed thin fibers (100–200 μm diameter) that retained varying water contents depending on Algn concentration. Higher Algn levels increased initial hydration but reduced water resorption after drying, indicating stronger Ca 2+ ‐mediated coagulation. Immersion in water caused selective elution of HPC, confirmed by consistent mass loss across samples. Crosslinking the fibers with hexamethylene diisocyanate (HMDI) enhanced mechanical strength, increasing load at break and modulus while reducing extensibility, particularly for fibers with ≥ 1.2 wt% Algn. Fiber diameter and surface fibril texture correlated positively with Algn content, while crosslinking preserved Ca 2+ ions within fiber matrices, maintaining coagulation integrity. This study elucidates the interplay of Algn concentration, Ca 2+ coagulation, and crosslinking on the hydration, mechanical properties, and morphology of HPC‐Algn composite fibers spun from aqueous solutions. The findings provide a foundation for tailoring polysaccharide composite fibers for biomedical and textile applications, with potential for incorporating secondary components to further modify functional properties.