Influence of sodium periodate-accelerated polydopamine modification of polyethylene fibers on fiber-matrix bonding in cementitious composites

Surface functionalization of polyethylene (PE) fibers with polydopamine (PDA) enhances the interfacial performance between fibers and cementitious matrices, influencing the efficiency of fiber reinforcements in cementitious composites. However, typical PDA modification requires a long treatment duration which is a major hurdle for practical applications. This paper introduces a facile strategy to rapidly modify PE fibers with dopamine (DA) by adding sodium periodate (SP) as an oxidizing agent. PE fibers were DA-modified with varied SP concentration and modification time; their surface properties were analyzed by environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and zeta potential measurements (ZP). The tensile strength and modulus of elasticity of the PE fibers were enhanced by 28% and 40%, respectively, through fast PDA modification. Micromechanical studies of the fibers embedded in cement depicted a considerable improvement in maximum pullout load, interfacial shear strength and pullout energy by the fiber functionalization. These improved properties can be ascribed to an increase in surface roughness, proved by AFM and ESEM, as well as a chemical activation of the PE fiber surface, demonstrated by XPS and ZP. Hence, the research findings provide an effective fast technique to functionalize PE fibers by PDA coating to achieve a stronger bond at the fiber/matrix interface, leading to an optimized fiber-reinforcing effect in cementitious composites.