(237f) Characterization of the Flexural Properties of Vapor-Grown Carbon Nanofiber/Vinyl Ester Nanocomposites by Experimental Design

The effects of four critical
formulation and processing factors on the flexural moduli and strengths of vapor-grown
carbon nanofiber (VGCNF)/vinyl ester (VE) nanocomposites were investigated using a mixed-level full
factorial experimental design. The factors included vapor-grown carbon nanofiber (VGCNF) type (pristine, surface-oxidized), use of
a dispersing agent (no, yes), mixing method (ultrasonication,
high-shear mixing, and a combination of both), and VGCNF weight fraction (0.00,
0.25, 0.50, 0.75, and 1.00 parts per hundred parts resin (phr)).
Response surface models were developed to predict
flexural moduli and strengths as a function of VGCNF weight fraction. The use
of surface-oxidized carbon nanofibers, a dispersing
agent, and high-shear mixing at 0.48 phr of VGCNF
gave an average increase of 19% in the flexural modulus over that of the neat
VE. High-shear mixing with 0.60 phr of VGCNF resulted
in a remarkable 49% increase of nanocomposite
flexural strength. This study highlights the use of design of experiments and
response surface modeling to both predict and optimize nanocomposite
mechanical properties.