High-Performance Large-Diameter PVA Composite Fibers Enhanced by Boron Nitride Nanosheets/Hyperbranched Polylysine

Research and development on inexpensive large-diameter polymer fibers with high mechanical and hydrophobic properties has become a hot topic in functional composites. Herein, boron nitride nanosheets (BNNS) were modified with hyperbranched polylysine (HBPL) via noncovalent interactions to obtain BNNS-HBPL, which were then incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate large-diameter PVA/BNNS-HBPL composite fibers by wet–dry spinning. The results demonstrated that the composite fibers exhibited optimal comprehensive performance at a BNNS-HBPL loading of 0.7 wt %, the crystallinity and orientation degree reached 53.9% and 96.8%, respectively, and the diameter was 130.5 dtex (113.1 μm). The tensile strength and initial modulus increased to 10.0 and 166.8 cN/dtex, representing improvements of 47.1% and 69.9% over pure PVA fibers, and the water contact angle increased to 101.8°. Finite element analysis (FEA) simulations revealed that the PVA/BNNS-HBPL composite fibers could effectively reduce the strain of the concrete through bridging and force-transferring effects in the concrete matrix. Accordingly, this work provides alternative insights into obtaining PVA/BNNS-HBPL composite fibers with strong mechanical and hydrophobic properties, indicating broad applications in concrete.