We report the observation of single nanotube fragmentation, under tens
ile stresses, using nanotube-containing thin polymeric films. Similar
fragmentation tests with single fibers instead of nanotubes are routin
ely performed to study the fiber-matrix stress transfer ability in fib
er composite materials, and thus the efficiency and quality of composi
te interfaces. The multiwall nanotube-matrix stress transfer efficienc
y is estimated to be at least one order of magnitude larger than in co
nventional fiber-based composites. (C) 1998 American Institute of Phys
ics.