ABSTRACT Electrospun polymer yarns are promising lightweight reinforcements but often underperform their constituent nanofibers owing to loose packing and inter‐fiber slip. We demonstrate a simple, twist‐free liquid‐assisted treatment—brief wetting with water or ethanol, followed by gentle stroking and controlled drying—that uses meniscus forces to compact PAN nanofibers into tightly bound bundles. The treatment yields large, repeatable gains in tensile modulus and strength; as diameter decreases, properties approach single‐nanofiber limits, evidencing improved load transfer. Dry‐rolling controls change little, confirming a capillarity‐driven mechanism. A minimal elastocapillary scaling, with driving set by surface tension and contact angle, explains two trends: water outperforms ethanol, and smaller radii compact more strongly. Microstructure quantified from SEM—alignment (orientation/coherency) and in‐plane packing fraction—predicts the variability in mechanical response across routes. A short anneal near T g further increases stiffness with a modest loss of ductility. We also present a constitutive model based on distributed fiber recruitment with frictional/adhesive contacts; it reproduces the stress–stretch curves and links the SEM descriptors to mechanical response. Capillary consolidation therefore provides a scalable lever to engineer processing–microstructure–property relationships in electrospun yarns and offers practical gains for polymer–matrix composite preforms via enhanced alignment, packing, and inter‐filament load transfer.
Mandal et al. (Fri,) studied this question.