Determination of carbon nanofiber morphology in vinyl ester nanocomposites

Abstract

Key aspects of nanofiber morphology in vapor-grown carbon nanofiber (VGCNF)/vinyl ester nanocomposites were characterized using transmission electron microscopy (TEM) images. Three-parameter Weibull probability density functions were generated to describe the statistical variation in nanofiber outer diameters, wall thicknesses, relative wall thicknesses, visible aspect ratios, and visible waviness ratios. Based upon a linear regression of experimental data, the relative nanofiber wall thicknesses were reasonably constant over a range of nanofiber radii. Such information could be used to establish more realistic nanofiber moduli and strengths obtained from nanofiber tensile tests, as well as to develop physically motivated computational models for predicting nanocomposite behavior. While the nanofiber aspect ratios and fiber waviness measurements were restricted to the visible portions of nanofibers lying in the plane of the TEM images, such data can be used to predict bounds on the effective nanocomposite elastic properties. This study represents one of the first attempts to experimentally characterize the distribution of VGCNF features in real thermoset nanocomposites.