Tunable effect of polyvinyl butyral nanofiber veil on fracture toughness of glass reinforced phenolic composites manufactured with out of autoclave method

This study proves the ability of polyvinyl butyral (PVB) nanofiber to improve the mode I and mode II interlaminar fracture toughness of out of autoclave phenolic-based composites. For investigation fracture behavior of glass-phenolic composites, a mode-I and mode II fracture test were carried out standard UD laminated and nanoweb interleaved specimens. PVB nanoweb with 25 μm thickness was placed in the laminate mid-planes which was subsequently subjected to a double cantilever beam and end-notched flexure tests. It was found that PVB nanofiber thanks to its excellent adhesion property with phenolic resin and unique features of nanoscales, has a tunable effect on improving mode I and mode II interlayer fracture toughness. PVB nanoweb provided the best all-round performance with fracture toughness improvements of 61% and 34.5% mode I and mode II, respectively; while, the maximum bending load has been improved.