Surface-Modified Electrospun Glass Nanofibers from Silane Treatment and Their Use for High-Performance Epoxy-Based Nanocomposite Materials

As a new and promising reinforcing filler, electrospun glass nanofibers (EGNFs) have attracted attention in the field of polymer composite materials. However, the reinforcing effectiveness of surface-modified EGNFs using different silane coupling agents in epoxy resin is still not quite clear. In this research, a series of silane coupling agents with increasing chain lengths in the order of methyl trimethoxysilane (MTMS), (3-aminopropyl) triethoxysilane (APTES), (3-glycidyloxypropyl) trimethoxysilane (GPTMS), and dual silane coupling agent APTES–GPTMS were employed to carry out surface treatment on the EGNFs. The pristine and silane functionalized EGNFs were then incorporated into epoxy resin as reinforcing fillers at low loading levels, i.e., 0.25 wt.%, 0.5 wt.%, and 1 wt.%, and the mechanical properties of the resultant epoxy nanocomposites, including strength, stiffness, ductility, and toughness, were evaluated. A commercial product of glass nanoparticles (GNPs) was used as a control to compare the reinforcing effectiveness of the EGNFs and the GNPs. This study revealed that the EGNFs could provide significant reinforcing and toughening effects at ultra-low loading (0.25 wt.%) in epoxy nanocomposite materials. Furthermore, surface modification of the EGNFs with silane coupling agents with long chain lengths, e.g., by using dual silane coupling agents, APTES–GPTMS, could enhance the interfacial bonding between the EGNFs and the epoxy matrix and further increase the mechanical performance of the EGNF-reinforced epoxy nanocomposite materials. Through this research, we realized epoxy nanocomposite materials with much-improved mechanical properties, i.e., 37%, 24%, 18%, 57% improvement in strength, stiffness, ductility, and toughness, respectively, with respect to those of the cured neat epoxy material with an ultra-low loading (0.25 wt.%) of APTES–GPTMS–EGNFs. Our research paves the road for developing lighter and stronger epoxy nanocomposite materials with EGNFs.