Effect of carbon nanotubes on the interfacial shear strength of T650/35 carbon fiber in an epoxy matrix using the single fiber fragmentation test
Conference Paper
Overview
Overview
abstract
The interfacial shear strength of carbon nanotube coated carbon fibers in epoxy was studied using the single-fiber composite fragmentation test. The carbon fibers were coated with carbon nanotubes (CNT) on the fiber using chemical vapor deposition (CVD). The CVD process was adjusted to produce two CNT morphologies for the study: aligned and unaligned. The purpose of the CNT coating was to produce an increase in the overall electrical conductivity of the composite while still maintaining the excellent mechanical properties associated with fiber-reinforced composites. The interfacial shear strength was studied in an effort to ensure the efficient transfer of load between the matrix and the fiber was maintained despite the presence of the CNT coating. The specimens were strained until fiber fragmentation ceased, at which point the number of fiber fragments was quantified. Analysis of the fragmentation test results was performed using the Kelly-Tyson stress transfer model for calculation of the interfacial shear strength. A Weibull distribution for the fiber tensile strength was also incorporated. The impact of the CNT morphologies, the CF surface preparation procedure, and sample preparation method were investigated. A specific challenge for vapor deposited CNT on carbon fiber is the retention of fiber tensile strength under oxidative growth conditions. Unaligned CNT coated fibers demonstrated a 65.8% increase in interfacial shear strength over untreated fibers. This can be attributed to an increase in the interphase yield strength due to the strengthening effect provided by the nanotubes. Radially aligned CNT coated fibers demonstrated a 5.9% increase in interfacial shear strength over untreated fibers, however these results were not statistically significant within this study.
