Hybrid Composites Utilizing Surface Grown Carbon Nanotubes

Fiber reinforced polymer (FRP) composites have been extensively utilized in automotive, marine, and aeronautics industries. While they offer many advantages compared to their metal counterparts, they suffer insufficient impact resistance and out-of-plane mechanical properties. A promising approach to improve FRPs inadequate properties is to integrate carbon nanotubes (CNTs) as filler additives in their polymer matrix. CNTs have extraordinary mechanical properties and can readily alleviate many of the shortcomings of FRP composites. When mixed with epoxy resins, CNTs tend to entangle and form detrimental agglomerates and drastically increase the epoxy viscosity to levels unsuitable for processing and effective fiber impregnation. These precludes CNT efficacy above ~2 weight percent loading in epoxy. One means to prevent nanotubes agglomeration is to anchor one end of the CNTs (during synthesis) to a substrate, thus creating a stable structure. The temperatures used in the available methods for direct growth of CNTs on carbon fibers, however, are rather high and very destructive to the fiber strength itself. Utilizing a novel low temperature CNT synthesis technique, we developed hybrid FRP composites based on surface grown CNTs on carbon fibers with superior impact and vibration performance. The advantages of this low temperature method over conventional routes for integration of CNTs are elucidated.