Hybrid multi-scale epoxy composites containing conventional glass microfibers and electrospun glass nanofibers with improved mechanical properties

A mechanically flexible mat consisting of structurally amorphous SiO2 (glass) nanofibers was first prepared by electrospinning followed by pyrolysis under optimized conditions and procedures. Thereafter, two types of hybrid multi-scale epoxy composites were fabricated via the technique of vacuum assisted resin transfer molding. For the first type of composites, six layers of conventional glass microfiber (GF) fabrics were infused with the epoxy resin containing shortened electrospun glass nanofibers (S-EGNFs). For the second type of composites, five layers of electrospun glass nanofiber mats (EGNF-mats) were sandwiched between six layers of conventional GF fabrics followed by the infusion of neat epoxy resin. For comparison, the (conventional) epoxy composites with six layers of GF fabrics alone were also fabricated as the control sample. Incorporation of EGNFs (i.e., S-EGNFs and EGNF-mats) into GF/epoxy composites led to significant improvements in mechanical properties, while the EGNF-mats outperformed S-EGNFs in the reinforcement of resin-rich interlaminar regions. The composites reinforced with EGNF-mats exhibited the highest mechanical properties overall; specifically, the impact absorption energy, interlaminar shear strength, flexural strength, flexural modulus, and work of fracture were (1097.3 +/- 48.5) J/m, (42.2 +/- 1.4) MPa, (387.1 +/- 9.9) MPa, (12.9 +/- 1.3) GPa, and (30.6 +/- 1.8) kJ/m(2), corresponding to increases of 34.6%, 104.8%, 65.4%, 33.0%, and 56.1% compared to the control sample. This study suggests that EGNFs (particularly flexible EGNF-mats) would be an innovative type of nanoscale reinforcement for the development of high-performance structural composites. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42731.