Processing and characterization of nanographene platelets modified phenolic resin as a precursor to carbon/carbon composites-part I

Nanographene platelets have been explored as nanofillers for resole type phenolic resin (GP 486G34) with catalyst (GP 4826C) supplied by Georgia Pacific Resins. Previous studies have shown that carbon nanofillers including single-walled carbon nanotubes, vapor-grown carbon nanofibers and graphite powder are shown to increase dimensional stability, carbon content and thermomechanical properties. In the present study, 0.5%, 1.5%, 3% and 5% by weight dispersions of nanographene platelets in phenolic resin were compared with corresponding dispersions of vapor-grown carbon nanofibers in phenolic resin to investigate the effect on curing reaction and rheological and wetting behaviors. 0.5 wt% nanographene platelets increased the heat of curing of neat phenolic resin by 33% compared with 26% increase in 0.5 wt% vapor-grown carbon nanofibers. Due to the mechanism of inter-platelet sliding of nanographene platelets, 0.5 wt% nanographene platelets reduced the steady shear viscosity of phenolic resin by 48% compared with that of neat resin after 1.5 h at 1% strain rate. The lower viscosity of 0.5 wt% nanographene platelets dispersion led to lower (20 degrees) contact angle compared with neat phenolic (29.57 degrees) with 8-harness satin weave carbon fabric after 10 s of contact with the fabric. Due to lower viscosity of nanographene platelets/phenolic dispersions and higher heat of curing, nanographene platelets could be potential carbon nanofiller for densifying carbon/carbon composites during manufacture.