Grafting SiO2 nanoparticles on polyvinyl alcohol fibers to enhance the interfacial bonding strength with cement

The weak interface bonding strength between organic fibers and inorganic cement is the main challenge for organic fiber-enhanced cement due to the lack of necessary physical and chemical affinity. In order to improve the interface bonding strength between polyvinyl alcohol (PVA) fibers and cement, SiO2 nanoparticles (SiO2 NPs) were grafted to high strength and high modulus PVA fibers using gamma-(2,3-epoxypropoxy) propytrimethoxysilane (KH560) as coupling agent. The grafted-PVA fibers were endowed with a Nano-rough surface and high chemical reactivity with cement. The orthogonal experimental results show that the optimal grafting rate between SiO2 NPs and PVA fibers was 8.5 wt% with reaction time of 2 h, reaction temperature of 110 degrees C, and catalyst weight percentage of 10 wt%. With SiO2-grafted PVA fibers as the enhancement, their tensile strength and pullout bonding strength in cement increased up to 21% and 43% compared with pure PVA fibers, respectively. The enhancement of interfacial behavior between PVA fiber and cement was further evidenced by the finite element analysis and simulation. In conclusion, grafting SiO2 NPs on PVA fibers can improve the interfacial bonding strength toward cement under small deformation, which implied the enhanced reinforcement and crack resistance for cement. This effect was primarily attributed to the synergistic friction and chemical bonding forces between SiO2 NPs and cement.