This paper demonstrates the viability of in-situ transmission electron micr
oscopy for studying the deformation mechanisms of polymer nano-composites.
In-situ straining studies are performed on carbon multiwalled nanotube (MWN
T)-polystyrene composite films. The experiments show that load transfer acr
oss the nanotube-polystyrene interface is operative well into the plastic d
eformation regime of the composite film. The MWNTs are observed to bridge c
racks propagating through the polystyrene, providing closure stresses acros
s the crack wake. Although some MWNTs fracture by either a sword-in-sheath
mechanism or transverse shear fracture, most of the MWNTs eventually debond
at the MWNT-polymer interface and subsequently pull out of the matrix.